TOHOKU UNIVERSITY Researchers

Makoto Ohta

Section

Institute of Fluid Science

Job title

Professor

Degree

博士（工学）（京都大学）
修士（工学）（京都大学）

researchmap

https://researchmap.jp/makoto_ohta

J-GLOBAL ID

200901039559034160

Research History 4

2022/03 - Present

Tohoku University　Graduate School of Biomedical Engineering　Professor
2022/03 - Present

Tohoku University　Graduate School of Engineering　Professor
2001/09 - 2004/12

University of Geneva　post-doctoral
2001/04 - 2001/09

Institute of Frontier Medical Sciences, Kyoto University　Lecturer (research worker of organization)

Education 2

Kyoto University　Graduate School, Division of Engineering　Department of Polymer Chemistry

- 2001/03
Tokyo University of Agriculture and Technology　Faculty of Engineering　Department of Materials and Bioengineering

- 1995/03/24

Committee Memberships 25

医療用立体モデルコンソーシアム　幹事

2019/08 - Present
戦略的国際標準化加速事業・政府戦略分野に係わる国際標準開発活動「バイオセラミックスの生物学的多能性評価に関する国際標準化」　委員

2019/04 - Present
Head

2019/04 - Present
ISO/TC150/WG14　議長

2018/10 - Present
日本生体医工学会東北支部　役員

2018/04 - Present
ISO/TC150 国内委員会　委員

2016/04 - Present
機械学会バイオエンジニアリング部門 A-TS02-16 脳神経血管内治療に関する医工学連携研究会　Head

2016/02 - Present
日本機械学会　編集委員

2013/01 - Present
経済産業省事業「AMによる患者適合型支援システム造形に関する国際標準」　委員

2020/04 - 2023/03
PMDA第4期科学委員会「コンピューターシミュレーションを活用した医療機器ソフトウエアの審査の考え方」専門部会　委員

2019/04 - 2021/03
日本機械学会東北支部 55期　商議委員会計幹事

2019/04 - 2021/03
Associate Editor

2019/04 - 2020/03
海綿骨モデルを含脊椎骨周辺のモデルの力学的測定方法に関する国際標準化委員会　PI

2017/04 - 2019/03
Intracranial Stent Meeting　HP管理

2009/09 - 2018/03
次世代医療機器・再生医療等製品評価指標作成事業血流解析シミュレーションソフトウェア分野審査ワーキンググループ　委員

2016/04 - 2018
模擬骨の3次元構造体に要求される特性に関する国際標準化委員会　PI

2014/04 - 2016/03
PMDA(独立行政法人医薬品医療機器総合機構)科学委員会委員　委員

2014/04 - 2016
PI

2011/04 - 2014/03
日本機械学会バイオエンジニアリング部門　運営委員会

2010/04 - 2012/03
日本機械学会バイオエンジニアリング部門　運営委員会

2010/04 - 2012/03
Intra cranial stent meeting 2006 (ICS06)　Program organizer of Intra cranial stent meeting 2006 (ICS06)

2005/03 - 2006/09
Intra cranial stent meeting 2006 (ICS06)　Intra cranial stent meeting 2006 (ICS06)のプログラム委員

2005/03 - 2006/09
Intra cranial stent meeting 2004 (ICS04)　oranizer of Intra cranial stent meeting 2004

2004/10 - 2005/01
Intra cranial stent meeting 2004(ICS04)　Intra cranial stent meeting 2004の実行委員

2004/10 - 2005/01
Intracranial Stent Meeting　admin of Web site

2009/09 -

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Professional Memberships 3

JAPANESE SOCIETY OF BIORHEOLOGY
JAPANESE SOCIETY FOR MEDICAL AND BIOLOGICAL ENGINEERING
THE JAPAN SOCIETY OF MECHANICAL ENGINEERS

Research Interests 7

oral
wear
interventional radiology
aneurysm
blood flow
3D reconstruction
biomodelling

Research Areas 4

Life sciences / Neurosurgery /
Manufacturing technology (mechanical, electrical/electronic, chemical engineering) / Fluid engineering /
Life sciences / Biomaterials /
Life sciences / Biomedical engineering /

Awards 20

日本機械学会フェロー

2021/02　日本機械学会
Poster Award(13th International IntraCranial Stent Meeting

2016/11/27　13th International IntraCranial Stent Meeting　Correlating MR Wall Enhancement and Wall Shear Stress: Does CFD work to predict aneurysm instability?
Poster Award(13th International IntraCranial Stent Meeting

2016/11/27　13th International IntraCranial Stent Meeting　Exploring the relationship between the inflow zone and strut positions within the aneurysm orifice: a hemodynamic simulation study
Poster Award(13th International IntraCranial Stent Meeting

2016/11/27　13th International IntraCranial Stent Meeting　Blood Flow Into Basilar Tip Aneurysms A Predictor for Recanalization After Coil Embolization
東北大学藤野先生記念奨励賞

2016/09/27　東北大学
ポスターアワード(生体医工学シンポジウム2016

2016/09/18　生体医工学シンポジウム　Introduction of Evaluation of Endoleak in Ink Flow Study
Best Student Presentation Award

2015/11/14　ICS2015　Student Presentation Award
Student Presentation Award

2015/11/14　ICS2015
ElyT Workshop 2014 best poster award

2015/02/20　ElyT　best poster award
Intracranial Stent Meeting 2012(ICS 2012) Best Abstract Presentation

2012/11/20　ICS2012
Intracranial Stent Meeting 2012(ICS 2012)

2012/11/20　ICS2012　Best Abstract Presentation
教育助成金プログラム 2011年度アジア部門1位

2012/11/04　エドモンド・オプティクス・ジャパン株式会社　PVAを用いた脳動脈瘤モデルにおける壁挙動とPIV計測
第23回日本脳神経血管内治療学会ポスター銀賞

2007/11　第23回日本脳神経血管内治療学会
第23回日本脳神経血管内治療学会優秀演題

2007/11　第23回日本脳神経血管内治療学会
Young Investigator Award

2005/11/21　The 6th International Symposium on Future Medical Engineering based on Bio-nanotechnology (21st Century COE Program)　Development of a Functional Vessel Biomodelling with Poly (vinyl alcohol) Hydrogel for In-vitro Simulation
The 20th annual meeting of The Japanese Society for Endovascular Treatment bronze prize

2004/11　第20回日本脳血管内治療年学会　Measurement of intra-aneurysmal flow dynamics at stent implant
Bronze Prizes The 20th annual meeting of The Japanese Society for Endovascular Treatment

2004/11　第20回日本脳血管内治療年学会　シネマティックアンジオを用いた、脳動脈瘤内の血流速さ測定法の開発(第一報)
poster prize

2004/09　European Society of Neuroradiology　ステントのストラッド径、ストラッド、effective postioningが脳動脈瘤内の血流に与える影響：有限要素法による解析
Silver Prize The 19th annual meeting of The Japanese Society for Intravascular Neurosurgery

2003/11　第19回日本脳血管内治療年学会　ステントのセルデザインが脳動脈瘤内の血流に与える影響：有限要素法による解析
Dr. Fernando Vinuela prize

2002/06　14th Society of International Latin America Neuroradiology　ステントが脳動脈瘤内の血流に与える影響

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Papers 359

Elongation of the proximal descending thoracic aorta and associated hemodynamics increase the risk of acute type B aortic dissection. International-journal

Xuelan Zhang, Yuan Peng, Gaoyang Li, Jiehua Li, Mingyao Luo, Yue Che, Liancun Zheng, Hitomi Anzai, Makoto Ohta, Chang Shu

Technology and health care : official journal of the European Society for Engineering and Medicine　2023/08/03

DOI： 10.3233/THC-230194 　

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BACKGROUND: Acute type B aortic dissection (ATBAD) is a life-threatening aortic disease. However, little information is available on predicting and understanding of ATBAD. OBJECTIVE: The study sought to explore the underlying mechanism of ATBAD by analyzing the morphological and hemodynamic characteristics related to aortic length. METHODS: The length and tortuosity of the segment and the whole aorta in the ATBAD group (n= 163) and control group (n= 120) were measured. A fixed anatomic landmark from the distal of left subclavian artery (LSA) to the superior border of sixth thoracic vertebra was proposed as the proximal descending thoracic aorta (PDTA), and the dimensionless parameter, length ratio, was introduced to eliminate the individual differences. The significant morphological parameters were filtrated and the associations between parameters were investigated using statistical approaches. Furthermore, how aortic morphology influenced ATBAD was explored based on idealized aortic models and hemodynamic-related metrics. RESULTS: The PDTA length was significantly increased in the ATBAD group compared with the control group and had a strong positive correlation with the whole aortic length (r= 0.89). The length ratio (LR2) and tortuosity (T2) of PDTA in the ATBAD group were significantly increased (0.15 ± 0.02 vs 0.12 ± 0.02 and 1.73 ± 0.48 vs 1.50 ± 0.36; P< 0.001), and LR2 was positive correlation with T2 (r= 0.73). In receiver-operating curve analysis, the area under the curve was 0.835 for LR2 and 0.641 for T2. Low and oscillatory shear (LOS) was positive correlation with LR2, and the elevated LOS occurred in the distal of LSA. CONCLUSION: Elongation of PDTA is associated with ATBAD, and the length ratio is a novel predictor. Elongated PDTA induced more aggressive hemodynamic forces, and high LOS regions may correspond to the entry tear location. The synergy of the morphological variation and aggressive hemodynamics creates contributory conditions for ATBAD.
Computational Fluid Dynamics Simulation to Investigate Diffuser Outlet Factors in Anaerobic Membrane Bioreactors Treating Wastewater

Haoran Wang, Makoto Ohta, Hitomi Anzai, Jiayuan Ji

SUSTAINABILITY　15　(15)　2023/08
Publisher: MDPI
DOI： 10.3390/su151511959 　

eISSN：2071-1050

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Anaerobic membrane bioreactors (AnMBRs) require biogas recycling to stir the mixed liquid and flush particles away from the membrane surfaces for stable operation. With the fixed gas cycling rate, gas diffuser configuration is an important factor that affects stirring and flushing performance. This study investigated the effect of different outlet diameters on biogas diffusers in AnMBR by using computational fluid dynamics (CFD) to analyze gas-liquid flow in a numerical model constructed based on an experimental AnMBR. According to the CFD results, as the outlet diameter increased from 2.5 to 5.0 mm, the average velocity increased from 0.15 to 0.31 m/s and the average wall shear stress (WSS) increased from 0.21 to 1.10 Pa on the membrane surface. The increase in gas velocity enhances the stirring effect, and the increase in WSS improves the flushing performance. However, when it was further increased to 10.0 mm, the average velocity and average WSS was 0.27 m/s and 0.22 Pa, respectively, indicating that too large an outlet diameter leads to a concentrated gas distribution, which reduces the performance of stirring and flushing. Furthermore, these results provide a basis for optimizing diffuser configuration, which is significant for promoting the practical application of AnMBR in wastewater treatment.
Ultrasound flow phantom for transcranial Doppler: An assessment of angular mismatch effect on blood velocity measurement in comparison to optical particle image velocimetry Peer-reviewed

Muhammad Shiddiq Sayyid Hashuro, Kotaro Daibo, Takuro Ishii, Yoshifumi Saijo, Makoto Ohta

Frontiers in Physics　11　2023/04/06
Publisher: Frontiers Media SA
DOI： 10.3389/fphy.2023.1134588 　

eISSN：2296-424X

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Detecting abnormal blood flow is possible through transcranial Doppler (TCD) ultrasound by measuring blood velocity in cerebral arteries. Velocity measurements are at the highest precision when the direction of blood flow coincides with the ultrasound beam. However, because TCD is typically performed blindly (i.e., without a B-mode), a 0° interrogation angle is usually assumed. This leads to a common issue of angular mismatch. This study quantitatively shows the angular mismatch effects on the measured velocities using a TCD ultrasound flow phantom compared with the velocities measured by optical particle image velocimetry (PIV) as control. Resulting errors with and without ultrasound machine angular correction were also considered. An ultrasound phantom developed by combining polyvinyl alcohol hydrogel (PVA-H), quartz glass as a scatterer, and a gypsum plate as a skull bone was utilized to approximate the middle cerebral artery TCD measurement from the temporal window. The PVA-H and quartz glass compositions were controlled to achieve transparency and enable PIV velocity measurement. Then, TCD velocity measurement was conducted on several interrogation and mismatch angles. Comparison results revealed that without an ultrasound machine angle correction, all measurements yielded underestimation with 73.9% at the highest in the 80° interrogation window at the 130 mL/min flow. On the other hand, with the correction, the errors in almost all angles were comparatively lower; however, at 80° at the 124 mL/min flow, a maximum overestimation rate of 113.7% was found, showing a larger error magnitude. Therefore, we find that angular mismatch, especially in larger angles, leads to inaccurate velocity measurements in TCD. Our results suggest that despite angle correction, velocity errors may still occur when the interrogation angle changes.
Effects of helical centerline stent vs. straight stent placement on blood flow velocity. International-journal

Yutaro Kohata, Makoto Ohta, Kazuyoshi Jin, Hitomi Anzai

Frontiers in medical technology　5　1196125-1196125　2023

DOI： 10.3389/fmedt.2023.1196125 　

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As an approach to maintain patency in femoropopliteal stenting, a helical stent configuration was proposed, which showed improved patency in clinical trials. However, the effects of helical stent placement on the flow have not been quantitatively analyzed. The purpose of this study was to estimate flow velocities to quantify the influence of helical stent placement. Helical and straight stents were implanted in three healthy pigs, and the flow velocities were estimated using the time-intensity curve (TIC) in the angiography images. The angiographic images indicated thinning of the leading edge of the contrast medium through the helically deformed artery, which was not observed in the straight stent. The slower rise of the TIC peak in the helical stent indicated faster travel of this thinner edge. Arterial expansion due to stenting was observed in all cases, and the expansion rate varied according to location. All cases of helical stent implantation showed that velocity was maintained (55.0%-71.3% velocity retention), unlike for straight stent implantation (43.0%-68.0% velocity retention); however, no significant difference was observed.
Migration of endothelial cells on the surface of anodized Ni-Ti stent strut. International-journal Peer-reviewed

Zi Wang, Naofumi Ohtsu, Kasumi Tate, Yukiko Kojima, Hanif Saifurrahman, Makoto Ohta

Frontiers in medical technology　5　1149594-1149594　2023

DOI： 10.3389/fmedt.2023.1149594 　

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BACKGROUND: Stent is widely regarded as the main treatment for curing cardiovascular diseases such as stenosis. Previous research has revealed that the damage of endothelial cells (EC), i.e., the components of endothelium, during stent implantation, could lead to severe complications, such as restenosis. To prevent restenosis, enhancements have been made to surface biocompatibility to accelerate the stent endothelialization process. Anodization on the Ni-Ti is a simple and efficient surface modification method to improve the biocompatibility of the Ni-Ti stent surfaces by enhancing the surface hydrophilicity, leading to an increase in the EC activities. The EC activity is known to be affected by the blood flow. Flow change by stent structure may result in EC dysfunctions, thereby leading to restenosis. It is thus essential to investigate the EC activities resulting from the anodization on the Ni-Ti surface under flow conditions. OBJECTIVE: To study the influence of the endothelialization process on the Ni-Ti stent surface through anodization. The EC attachment and morphology on the anodized stent strut were observed under both with and without the flow conditions. METHOD: A parallel plate flow chamber was designed to generate a constant wall shear stress (WSS) to study the flow effect on the EC behavior. The hydrophilicity of the Ni-Ti stent strut surface was enhanced by a TiO2 layer fabricated via anodization. The EC distribution on the surface of the anodized nitinol stent strut was observed after 24 h of static (without flow) and flow exposure (with flow) experiment. RESULTS: Under the static condition, the EC density on the surface of the anodized Ni-Ti stent strut was higher compared with the control. Under the flow condition, the enhancement of the EC density on the surface of the stent strut with anodization was reduced. The EC demonstrates a long and thin spindle-shaped morphology under the flow condition. CONCLUSION: Unlike the static condition, the EC is demonstrating a long and thin morphology in response to the flow under the flow condition. By improving the surface hydrophilicity, the anodization could enhance the EC migration onto the strut surface, and subsequently, accelerate the Ni-Ti stent endothelialization process. The improvement of the surface hydrophilicity is lower under the flow conditions when compared with the static conditions.
Development of Ultrasound Phantom Made of Transparent Material: Feasibility of Optical Particle Image Velocimetry International-journal Peer-reviewed

Muhammad Shiddiq Sayyid Hashuro, Simon Tupin, Narendra Kurnia Putra, Kotaro Daibo, Kosuke Inoue, Takuro Ishii, Hiroyuki Kosukegawa, Kenichi Funamoto, Toshiyuki Hayase, Makoto Ohta

Ultrasound in Medicine and Biology　in press　(6)　1385-1394　2023

DOI： 10.1016/j.ultrasmedbio.2022.12.020 　

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OBJECTIVE: The need for ultrasound flow phantoms to validate ultrasound systems requires the development of materials that can clearly visualize the flow inside for measurement purposes. METHODS: A transparent ultrasound flow phantom material composed of poly(vinyl alcohol) hydrogel (PVA-H) with dimethyl sulfoxide (DMSO) and water solution manufactured using the freezing method and mixed with quartz glass powder to exhibit scattering effects is proposed. To achieve transparency of the hydrogel phantom, the refractive index (RI) was changed to match that of the glass by modifying the PVA concentration and the ratio of DMSO to water in the solvent. The feasibility of optical particle image velocimetry (PIV) was verified by comparing an acrylic rectangular cross-section channel with a rigid wall. After the feasibility tests, an ultrasound flow phantom was fabricated to conduct ultrasound B-mode visualization and Doppler-PIV comparison. DISCUSSION: The results revealed that the PIV measured through PVA-H material exhibited 0.8% error in the measured maximum velocity compared with PIV through the acrylic material. B-mode images are similar to real tissue visualization with a limitation of a higher sound velocity, when compared with human tissue, of 1792 m/s. Doppler measurement of the phantom revealed approximately 120% and 19% overestimation of maximum and mean velocities, respectively, compared with those from PIV. CONCLUSION: The proposed material possesses the advantage of the single-phantom ability to improve the ultrasound flow phantom for validation of flow.
Numerical simulation to evaluate guidewire and catheter behavior during catheter introduction Peer-reviewed

Kazuto TAKASHIMA, Akinori NAMBA, Hiroto OTA, Yoichi HAGA, Makoto OHTA, Koji MORI, Naoki TOMA, Masaaki SHOJIMA

Bulletin of the JSME Journal of Biomechanical Science and Engineering　18　(1)　1-12　2022/12

DOI： 10.1299/jbse.22-00276 　
Coupled discrete phase model and Eulerian wall film model for numerical simulation of respiratory droplet generation during coughing International-journal Peer-reviewed

Hitomi Anzai, Yugo Shindo, Yutaro Kohata, Masahiro Hasegawa, Hidemasa Takana, Tetsuro Matsunaga, Takaaki Akaike, Makoto Ohta

Scientific reports　12　(1)　14849-14849　2022/09/01

DOI： 10.1038/s41598-022-18788-3 　

eISSN：2045-2322

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Computational fluid dynamics is widely used to simulate droplet-spreading behavior due to respiratory events. However, droplet generation inside the body, such as the number, mass, and particle size distribution, has not been quantitatively analyzed. The aim of this study was to identify quantitative characteristics of droplet generation during coughing. Airflow simulations were performed by coupling the discrete phase model and Eulerian wall film model to reproduce shear-induced stripping of airway mucosa. An ideal airway model with symmetric bifurcations was constructed, and the wall domain was covered by a mucous liquid film. The results of the transient airflow simulation indicated that the droplets had a wide particle size distribution of 0.1-400 µm, and smaller droplets were generated in larger numbers. In addition, the total mass and number of droplets generated increased with an increasing airflow. The total mass of the droplets also increased with an increasing mucous viscosity, and the largest number and size of droplets were obtained at a viscosity of 8 mPa s. The simulation methods used in this study can be used to quantify the particle size distribution and maximum particle diameter under various conditions.
A Software to Visualize, Edit, Model and Mesh Vascular Networks. International-journal

Meghane Decroocq, Guillaume Lavoue, Makoto Ohta, Carole Frindel

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference　2022　2208-2214　2022/07

DOI： 10.1109/EMBC48229.2022.9871365 　

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Computational fluid dynamics (CFD) is a key tool for a wide range of research areas, beyond the computer science community. In particular, CFD is used in medicine to measure blood flow from patient specific models of arteries. In this field, the creation of accurate meshes remains the most challenging step, as it is based on the segmentation of medical images, a time-consuming task which often requires manual intervention by medical doctors. In this context, user-friendly, interactive softwares are valuable. They enable to spread the new advances in numerical treatment to the medical community and enrich them with the expert knowledge (e.g anatomical knowledge) of clinicians. In this work, we present a user interface dedicated to the meshing of vascular networks from centerlines. It allows for the 3D visualization and edition of input centerlines, which constitute a simplified, easy-to-manipulate representation of vascular networks. The surface of the artery can be reconstructed from the modified centerlines by an editable parametric model and then meshed with high quality hexahedral elements. At every step of the process, the network can be confronted with medical images with enhanced visualization. The software will be released publicly. Clinical relevance- This tool facilitates the manual extraction and editing of vascular networks by medical doctors. It opens the generation of hexahedral meshes for computational fluid dynamics studies to non-expert users.
Experimental Study of Collateral Patency following Overlapped Multilayer Flow Modulators Deployment Peer-reviewed

Simon Tupin, Kei Takase, Makoto Ohta

Fluids　7　(7)　220-220　2022/06/30
Publisher: MDPI AG
DOI： 10.3390/fluids7070220 　

eISSN：2311-5521

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Decades after its introduction, endovascular aneurysm repair remains a challenging procedure with risks of collateral patency failure. Here, we investigate the ability of a porous stent, the Multilayer Flow Modulator (MFM), to maintain renal perfusion after a single or overlapping case. Silicone models representing an ideal infrarenal AAA geometry were used to analyze and compare three cases (control, single MFM and two overlapped MFMs). Micro-computed tomography was used to image the deployed MFM devices geometry and evaluate pore size and density along with porosity in both two (planimetric) and three dimensions (gravimetric). Laser particle image velocimetry (PIV) experiments were performed to image velocity and vorticity fields at the aorta-renal bifurcation. Flow experiments revealed renal arteries perfusion preservation in both single and overlapped cases. Microstructure analysis revealed an uneven distribution of wires in the MFM devices leading to local change in planimetric porosity and pore size. Overlap of a second MFM device led to a significant decrease in those 2D metrics but did not affect the gravimetric porosity and the branch perfusion. This first microstructure evaluation of MFM device combined with flow experiments revealed the ability of the device to preserve collateral flow thanks to a highly porous microstructure.
A Parametric Study of Flushing Conditions for Improvement of Angioscopy Visibility Peer-reviewed

Kohei Mitsuzuka, Yujie Li, Toshio Nakayama, Hitomi Anzai, Daisuke Goanno, Simon Tupin, Mingzi Zhang, Haoran Wang, Kazunori Horie, Makoto Ohta

JOURNAL OF FUNCTIONAL BIOMATERIALS　13　(2)　2022/06
Publisher: MDPI
DOI： 10.3390/jfb13020069 　

eISSN：2079-4983

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During an angioscopy operation, a transparent liquid called dextran is sprayed out from a catheter to flush the blood away from the space between the camera and target. Medical doctors usually inject dextran at a constant flow rate. However, they often cannot obtain clear angioscopy visibility because the flushing out of the blood is insufficient. Good flushing conditions producing clear angioscopy visibility will increase the rate of success of angioscopy operations. This study aimed to determine a way to improve the clarity for angioscopy under different values for the parameters of the injection waveform, endoscope position, and catheter angle. We also determined the effect of a stepwise waveform for injecting the dextran only during systole while synchronizing the waveform to the cardiac cycle. To evaluate the visibility of the blood-vessel walls, we performed a computational fluid dynamics (CFD) simulation and calculated the visible area ratio (VAR), representing the ratio of the visible wall area to the total area of the wall at each point in time. Additionally, the normalized integration of the VAR called the area ratio (AR(VAR)) represents the ratio of the visible wall area as a function of the dextran injection period. The results demonstrate that the AR(VAR) with a stepped waveform, bottom endoscope, and three-degree-angle catheter results in the highest visibility, around 25 times larger than that under the control conditions: a constant waveform, a center endoscope, and 0 degrees. This set of conditions can improve angioscopy visibility.
Development of Device Placement Simulator for Endovascular Treatment: (Effect of Coil Insertion Conditions)

OISHI Takuya, TAKASIMA Kazuto, YOSHINAKA Kiyoshi, YU Kaihong, OHTA Makoto, MORI Koji, TOMA Naoki

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2022.32　1C24　2022
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2022.32.1c24 　

eISSN：2424-2810
Evaluation of Normalization Methods in a Cerebral Artery Atlas for Automatic Labeling

Kazuyoshi Jin, Ko Kitamura, Shunji Mugikura, Naoko Mori, Makoto Ohta, Hitomi Anzai

Volume 5: Biomedical and Biotechnology　2021/11/01
Publisher: American Society of Mechanical Engineers
DOI： 10.1115/imece2021-71097 　

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Abstract An existence probability atlas has been used for automatic labeling of cerebral arteries. However, the number of arteries varies frequently because of image quality and individual variation of the artery structure. To moderate the influence of number imbalance on labeling accuracy, we propose a new normalized atlas for automatic labeling of cerebral artery centerlines. The number of arteries, which was obtained from magnetic resonance angiography, varies from 11 to 46 among the artery sites. Based on the centerline and diameter, the arterial volume was reconstructed into a voxel space for each subject. After superimposing arteries from 46 subjects, three normalization methods were compared: dividing by the number of subjects (N), by N and the arterial length (L), and by N and the arterial volume (V). To compare the labeling accuracy and precision, the summation of probability and labeling method was also used. The accuracy of all normalization methods was &gt; 85% in all arteries. The precision improved in some parts, with the atlas normalized by N-L and by N-V. The use of N-L and N-V changed the relative value of the existence probability among the parts. Consequently, some normalization methods changed the tendency toward misclassification, which changed the precision.
Assessment of the thermal outcome during steam-pulse ablation for sheep tissue

Hitomi Anzai, Rolf Stämpfli, Adriano Wang-Leandro, Luciano F. Boesel, Shelley Kemp, Rene M. Rossi, Agnieszka A. Karol, Makoto Ohta, Henning Richter

Thermal Science and Engineering Progress　25　100966-100966　2021/10
Publisher: Elsevier BV
DOI： 10.1016/j.tsep.2021.100966 　

ISSN：2451-9049
Experimental Analysis of Pressure and Flow Alterations During and After Insertion of a Multilayer Flow Modulator into an AAA Model with Incorporated Branch International-journal Peer-reviewed

Simon Tupin, Kei Takase, Makoto Ohta

CardioVascular and Interventional Radiology　44　(8)　1251-1259　2021/08/27
Publisher: Springer Science and Business Media {LLC}
DOI： 10.1007/s00270-021-02835-z 　

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PURPOSE: The multilayer flow modulator (MFM) device has been used for the treatment of abdominal aortic aneurysm (AAA) for over a decade. Although several clinical studies have been published, criticism and concern over the device efficacy remain, as no quantitative analysis that describes its mechanism has been performed yet. The aim of this study was to experimentally evaluate the effect of MFM device deployment on aneurysmal pressure and branch perfusion. MATERIALS AND METHODS: An experimental flow and pressure monitoring system was developed to analyze the MFM deployment procedure performed by a qualified radiologist in AAA geometries with and without side branch. Particle image velocimetry experiments were then conducted on models with and without MFM device to evaluate and compare flow patterns and local flow velocity and vorticity in the aneurysm. RESULTS: The experiments revealed no significant change in pressure and flow rate during and after deployment of the MFM device. The flow rate of the incorporated branch was fully preserved. On both models, the aneurysmal flow velocity was significantly reduced. In addition, the device modified local flow patterns, reducing vorticity and better feeding the incorporated branch. CONCLUSION: This experimental study provides the basis for a better understanding of the mechanism of the MFM device, which allows intra-aneurysmal flow to decrease while preserving incorporated branch flow and reducing the risk of type II endoleak. The experimental system developed for this study was effective in simulating an endovascular procedure and studying the safety and effectiveness of endovascular devices.
Finite element analysis of the mechanical performance of a zinc alloy stent with the tenon-and-mortise structure. International-journal

Sirui Wang, Dandan Wu, Gaoyang Li, Kun Peng, Yongliang Mu, Makoto Ohta, Hitomi Anzai, Aike Qiao

Technology and health care : official journal of the European Society for Engineering and Medicine　2021/07/23

DOI： 10.3233/THC-212905 　

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BACKGROUND: Inadequate scaffolding performance hinders the clinical application of the biodegradable zinc alloy stents. OBJECTIVE: In this study we propose a novel stent with the tenon-and-mortise structure to improve its scaffolding performance. METHODS: 3D models of stents were established in Pro/E. Based on the biodegradable zinc alloy material and two numerical simulation experiments were performed in ABAQUS. Firstly, the novel stent could be compressed to a small-closed ring by a crimp shell and can form a tenon-and-mortise structure after expanded by a balloon. Finally, 0.35 MPa was applied to the crimp shell to test the scaffolding performance of the novel stent and meanwhile compare it with an ordinary stent. RESULTS: Results showed that the novel stent decreased the recoiling ratio by 70.7% compared with the ordinary stent, indicating the novel structure improved the scaffolding performance of the biodegradable zinc alloy stent. CONCLUSION: This study proposes a novel design that is expected to improve the scaffolding performance of biodegradable stents.
Incomplete stent expansion in flow‐diversion treatment affects aneurysmal haemodynamics: a quantitative comparison of treatments affected by different severities of malapposition occurring in different segments of the parent artery International-journal

Mingzi Zhang, Yujie Li, Shin‐ichiro Sugiyama, David I. Verrelli, Yasushi Matsumoto, Teiji Tominaga, Yi Qian, Simon Tupin, Hitomi Anzai, Makoto Ohta

International Journal for Numerical Methods in Biomedical Engineering　37　(7)　e3465　2021/07/17
Publisher: Wiley
DOI： 10.1002/cnm.3465 　

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Incomplete stent expansion (IncSE) is occasionally seen in flow-diversion (FD) treatment of intracranial aneurysms; however, its haemodynamic consequences remain inconclusive. Through a parametric study, we quantify the aneurysmal haemodynamics subject to different severities of IncSE occurring in different portions of the stent. Two patient cases with IncSE confirmed in vivo were studied. To investigate a wider variety of IncSE scenarios, we modelled IncSE at two severity levels respectively located in the proximal, central, or distal segment of a stent, yielding a total of 14 treatment scenarios (including the ideal deployment). We examined stent wire configurations in 14 scenarios and resolved aneurysm haemodynamics through computational fluid dynamics (CFD). A considerable degradation of aneurysm flow-reduction performance was observed when central or distal IncSE occurred, with the maximal elevations of the inflow rate (IR) and energy loss (EL) being 10% and 15%. The underlying mechanism might be the increased resistance for flow to remain within the FD stent, which forces more blood to leak into the aneurysm sac. Counter-intuitively, a slight reduction of aneurysm inflow was associated with proximal IncSE, with the maximal further reduction of the IR and EL being 5% and 8%. This may be due to the disruption of the predominant parent-artery flow by the collapsed wires, which decreased the strength and altered the direction of aneurysmal inflow. The effects of IncSE vary greatly with the location of occurrence, revealing the importance of performing individualised, patient-specific risk assessment before treatment.
Virtual Angiography System as a Platform for Blood Flow estimation

Y. Kohata, H. Anzai, M. Decroocq, S. Rit, C. Frindel, M. Ohta

33-34　2021/06
Tribology for health devices: 15 years of collaboration between Tohoku University (Ohta lab) and ECL (LTDS)

M.Ohta, V. Fridrici

LyonSE&N & ELyT workshop 2021 / JSPS Core to core 1st symposium　29-30　2021/06
CTA-Based Non-invasive Estimation of Pressure Gradients Across a CoA: a Validation Against Cardiac Catheterisation. International-journal

Mingzi Zhang, Jinlong Liu, Haibo Zhang, David I Verrelli, Qian Wang, Liwei Hu, Yujie Li, Makoto Ohta, Jinfen Liu, Xi Zhao

Journal of cardiovascular translational research　14　(5)　873-882　2021/03/04

DOI： 10.1007/s12265-020-10092-7 　

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Non-invasive estimation of pressure gradients across a coarctation of the aorta (CoA) can reduce the need for diagnostic cardiac catheterisation. We aimed to validate two novel computational strategies-target-value approaching (TVA) and target-value fixing (TVF)-together with unrefined Doppler estimates, and to compare their diagnostic performance in identifying critical pressure drops for 40 patients. Compared to catheterisation, no statistically significant difference was demonstrated with TVA (P = 0.086), in contrast to TVF (P = 0.005) and unrefined Doppler echocardiography (P < 0.001). TVA manifested the strongest correlation with catheterisation (r = 0.93), compared to TVF (r = 0.83) and echocardiography (r = 0.67) (all P < 0.001). In discriminating pressure gradients greater than 20 mmHg, TVA, TVF, and echocardiography had respective sensitivities of 0.92, 0.88, and 0.80; specificities of 0.93, 0.80, and 0.73; and AUCs of 0.96, 0.89, and 0.80. The TVA strategy may serve as an effective and easily implemented approach to be used in clinical management of patients with CoA. Graphical Abstract Central illustration. Pressure gradients estimated using Doppler echocardiography and two novel computational strategies (TVA and TVF) were compared with cardiac catheterisation for 40 patients. TVA and TVF utilised the CTA images to obtain the CoA anatomy and Doppler echocardiography velocimetry to obtain velocity data for the assignment of CFD boundary conditions.
Implementation of computer simulation to assess flow diversion treatment outcomes: systematic review and meta-analysis International-journal Peer-reviewed

Mingzi Zhang, Simon Tupin, Hitomi Anzai, Yutaro Kohata, Masaaki Shojima, Kosuke Suzuki, Yoshihiro Okamoto, Katsuhiro Tanaka, Takanobu Yagi, Soichiro Fujimura, Makoto Ohta

JOURNAL OF NEUROINTERVENTIONAL SURGERY　13　(2)　164-170　2021/02
Publisher: BMJ PUBLISHING GROUP
DOI： 10.1136/neurintsurg-2020-016724 　

ISSN：1759-8478

eISSN：1759-8486

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IntroductionDespite a decade of research into virtual stent deployment and the post-stenting aneurysmal hemodynamics, the hemodynamic factors which correlate with successful treatment remain inconclusive. We aimed to examine the differences in various post-treatment hemodynamic parameters between successfully and unsuccessfully treated cases, and to quantify the additional flow diversion achievable through stent compaction or insertion of a second stent.MethodsA systematic review and meta-analysis were performed on eligible studies published from 2000 to 2019. We first classified cases according to treatment success (aneurysm occlusion) and then calculated the pooled standardized mean differences (SMD) of each available parameter to examine their association with clinical outcomes. Any additional flow diversion arising from the two common strategies for improving the stent wire density was quantified by pooling the results of such studies.ResultsWe found that differences in the aneurysmal inflow rate (SMD -6.05, 95% CI -10.87 to -1.23, p=0.01) and energy loss (SMD -5.28, 95% CI -7.09 to -3.46, p<0.001) between the successfully and unsuccessfully treated groups were indicative of statistical significance, in contrast to wall shear stress (p=0.37), intra-aneurysmal average velocity (p=0.09), vortex core-line length (p=0.46), and shear rate (p=0.09). Compacting a single stent could achieve additional flow diversion comparable to that by dual-stent implantation.ConclusionsInflow rate and energy loss have shown promise as identifiers to discriminate between successful and unsuccessful treatment, pending future research into their diagnostic performance to establish optimal cut-off values.
Prediction of 3D Cardiovascular hemodynamics before and after coronary artery bypass surgery via deep learning. International-journal

Gaoyang Li, Haoran Wang, Mingzi Zhang, Simon Tupin, Aike Qiao, Youjun Liu, Makoto Ohta, Hitomi Anzai

Communications biology　4　(1)　99-99　2021/01/22

DOI： 10.1038/s42003-020-01638-1 　

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The clinical treatment planning of coronary heart disease requires hemodynamic parameters to provide proper guidance. Computational fluid dynamics (CFD) is gradually used in the simulation of cardiovascular hemodynamics. However, for the patient-specific model, the complex operation and high computational cost of CFD hinder its clinical application. To deal with these problems, we develop cardiovascular hemodynamic point datasets and a dual sampling channel deep learning network, which can analyze and reproduce the relationship between the cardiovascular geometry and internal hemodynamics. The statistical analysis shows that the hemodynamic prediction results of deep learning are in agreement with the conventional CFD method, but the calculation time is reduced 600-fold. In terms of over 2 million nodes, prediction accuracy of around 90%, computational efficiency to predict cardiovascular hemodynamics within 1 second, and universality for evaluating complex arterial system, our deep learning method can meet the needs of most situations.
Emerging Technologies for Heart Diseases. International-journal

Makoto Ohta

Technology and health care : official journal of the European Society for Engineering and Medicine　29　(5)　1047-1048　2021

DOI： 10.3233/THC-212909 　
Effect of positioning of blood vessel on the hemodynamics prediction accuracy by deep learning

Shiraishi Keiichiro, Ohta Makoto, Anzai Hitomi, Li Gaoyang

Transactions of Japanese Society for Medical and Biological Engineering　Annual59　(Abstract)　510-510　2021
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.annual59.510 　

ISSN：1347-443X

eISSN：1881-4379

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We have developed a novel deep learning network model to predict the hemodynamics in a short time from the aorta shape. However this network model needs a location registration in advance. The aim of this study is to find out relations between the location gap of the input data and prediction accuracy.Prediction accuracy was evaluated by the mean square error(MSE) of the velocity. The area where the training data exists was called the training range. One test data was located inside and outside of this range. Within the training range, there is the position where the prediction accuracy becomes higher than the original position. Outside of the range, there is non-linear tendency of sudden drop in accuracy. The errors become particularly large in the part where the patient-specific flow is observed.This study showed the importance of the location registration for the prediction accuracy on our network model.
Numerical Simulation of Flow Behavior in Basilar Bifurcation Aneurysms Based on 4-Dimensional Computed Tomography Angiography

Tomoaki Yamazaki, Gaku Tanaka, Ryuhei Yamaguchi, Yodai Okazaki, Hitomi Anzai, Fujimaro Ishida, Makoto Ohta

World Journal of Mechanics　11　(04)　71-82　2021
Publisher: Scientific Research Publishing, Inc.
DOI： 10.4236/wjm.2021.114006 　

ISSN：2160-049X

eISSN：2160-0503
Association Between Aneurysmal Haemodynamics and Device Microstructural Characteristics After Flow-Diversion Treatments With Dual Stents of Different Sizes: A Numerical Study. International-journal

Mingzi Zhang, Simon Tupin, Yujie Li, Makoto Ohta

Frontiers in physiology　12　663668-663668　2021

DOI： 10.3389/fphys.2021.663668 　

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Objectives: Treating intracranial aneurysms with flow-diverting stents sometimes requires deployment of a second device. Herein we quantify the sizing effects of devices in dual-stent treatments upon the final stent microstructure and the post-treatment aneurysmal haemodynamics. Methods: Fifteen sidewall ICA aneurysm geometries were included. Using a virtual stenting technique, we implanted either one or two stents for each aneurysm treatment considered, with each stent specified as one of two different sizes, yielding a total of two single-stent and fouir dual-stent treatment scenarios for each aneurysm. Three stent microstructural parameters and nine aneurysmal haemodynamic parameters were quantified and systematically compared across the 90 treatment scenarios. Results: Deployment of a second stent further reduced the aneurysmal inflow rate (IR) and energy loss (EL) by, respectively, 14 ± 11% (p = 0.001) and 9 ± 12% (p = 0.056), relative to the untreated condition. Sizing effects of the earlier-deployed stent led to largest differences of 6.9% for the final IR reduction and 11.1% for the EL, whereas sizing effects from the later-deployed stent were minor (≤2.1%). The change in stent pore size was the only microstructural parameter demonstrating a strong correlation with the reduction in the post-treatment aneurysmal haemodynamics, in terms of the IR (r = 0.50, p < 0.001) and pressure drop (r = 0.63, p < 0.001). Conclusion: Size of the earlier-deployed stent has substantial effects on the final haemodynamic outcomes after dual-stent treatment. The average pore size of stent wires at the aneurysm orifice shows promise as a potential index for predicting the efficacy of flow-diversion treatments.
Flush Flow Behaviour Affected by the Morphology of Intravascular Endoscope: A Numerical Simulation and Experimental Study. International-journal

Yujie Li, Mingzi Zhang, Simon Tupin, Kohei Mitsuzuka, Toshio Nakayama, Hitomi Anzai, Makoto Ohta

Frontiers in physiology　12　733767-733767　2021

DOI： 10.3389/fphys.2021.733767 　

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Background: Whilst intravascular endoscopy can be used to identify lesions and assess the deployment of endovascular devices, it requires temporary blockage of the local blood flow during observation, posing a serious risk of ischaemia. Objective: To aid the design of a novel flow-blockage-free intravascular endoscope, we explored changes in the haemodynamic behaviour of the flush flow with respect to the flow injection speed and the system design. Methods: We first constructed the computational models for three candidate endoscope designs (i.e., Model A, B, and C). Using each of the three endoscopes, flow patterns in the target vessels (straight, bent, and twisted) under three different sets of boundary conditions (i.e., injection speed of the flush flow and the background blood flowrate) were then resolved through use of computational fluid dynamics and in vitro flow experiments. The design of endoscope and its optimal operating condition were evaluated in terms of the volume fraction within the vascular segment of interest, as well as the percentage of high-volume-fraction area (PHVFA) corresponding to three cross-sectional planes distal to the microcatheter tip. Results: With a mild narrowing at the endoscope neck, Model B exhibited the highest PHVFA, irrespective of location of the cross-sectional plane, compared with Models A and C which, respectively, had no narrowing and a moderate narrowing. The greatest difference in the PHVFA between the three models was observed on the cross-sectional plane 2 mm distal to the tip of the microcatheter (Model B: 33% vs. Model A: 18%). The background blood flowrate was found to have a strong impact on the resulting volume fraction of the flush flow close to the vascular wall, with the greatest difference being 44% (Model A). Conclusion: We found that the haemodynamic performance of endoscope Model B outperformed that of Models A and C, as it generated a flush flow that occupied the largest volume within the vascular segment of interest, suggesting that the endoscope design with a diameter narrowing of 30% at the endoscope neck might yield images of a better quality.
Endothelial Cell Distribution After Flow Exposure With Two Stent Struts Placed in Different Angles. International-journal Peer-reviewed

Zi Wang, Narendra Kurnia Putra, Hitomi Anzai, Makoto Ohta

Frontiers in physiology　12　733547-733547　2021

DOI： 10.3389/fphys.2021.733547 　

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Stent implantation has been a primary treatment for stenosis and other intravascular diseases. However, the struts expansion procedure might cause endothelium lesion and the structure of the struts could disturb the blood flow environment near the wall of the blood vessel. These changes could damage the vascular innermost endothelial cell (EC) layer and pose risks of restenosis and post-deployment thrombosis. This research aims to investigate the effect of flow alterations on EC distribution in the presence of gap between two struts within the parallel flow chamber. To study how the gap presence impacts EC migration and the endothelialization effect on the surface of the struts, two struts were placed with specific orientations and positions on the EC layer in the flow chamber. After a 24-h exposure under wall shear stress (WSS), we observed the EC distribution conditons especially in the gap area. We also conducted computational fluid dynamics (CFD) simulations to calculate the WSS distribution. High EC-concentration areas on the bottom plate corresponded to the high WSS by the presence of gap between the two struts. To find the relation between the WSS and EC distributions on the fluorescence images, WSS condition by CFD simulation could be helpful for the EC distribution. The endothelialization rate, represented by EC density, on the downstream sides of both struts was higher than that on the upstream sides. These observations were made in the flow recirculation at the gap area between two struts. On two side surfaces between the gaps, meaning the downstream at the first and the upstream at the second struts, EC density differences on the downstream surfaces of the first strut were higher than on the upstream surfaces of the second strut. Finally, EC density varied along the struts when the struts were placed at tilted angles. These results indicate that, by the presence of gap between the struts, ECs distribution could be predicted in both perpendicular and tiled positions. And tiled placement affect ECs distribution on the strut side surfaces.
Evaluation of Contact Force between Aneurysm Model and Coil for Embolization of Intracranial Aneurysms

Kazuto Takashima, Yuta Ikeda, Kiyoshi Yoshinaka, Makoto Ohta, Koji Mori, Naoki Toma

Journal of Neuroendovascular Therapy　15　(4)　233-239　2021
Publisher: The Japanese Society for Neuroendovascular Therapy
DOI： 10.5797/jnet.oa.2020-0069 　

ISSN：1882-4072

eISSN：2186-2494
Hemodynamic and Flow Recirculation Effect on Rupture Prediction of Middle Cerebral Artery Aneurysm

Nadia Shaira Shafii, Ryuhei Yamaguchi, Ahmad Zahran Md Khudzari, Gaku Tanaka, Atsushi Saitoh, Makoto Ohta, Kahar Osman

Journal of Advanced Research in Fluid Mechanics and Thermal Sciences　79　(1)　1-16　2020/12/15
Publisher: Akademia Baru Publishing
DOI： 10.37934/arfmts.79.1.116 　

eISSN：2289-7879

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The mortality and morbidity rate due to the severe effect of intracranial aneurysm (IA) is increasing, which has driven research trend on aneurysm rupture risk. By understanding the nature and causes of the aneurysm rupture, preventive measures could be taken in avoiding rupture besides recommending proper treatments such as endovascular coiling. However, the presence of flow recirculation causes the aneurysm wall to degenerate and weakened. The weakened wall is due to the haemodynamic factors such as velocity, wall shear stress (WSS), time average WSS (TAWSS), OSI and RRT, which were analysed in this study. In the present study, the flow model simulated a human patient-specific aneurysm at the apex of the bifurcation in the middle cerebral artery (MCA) in the transient state. Experimental results of full-scale models were collected on a median, side plane to study the flow behaviour and validation to the numerical simulation settings, which resulted in good agreement with only 8% difference. The simulation results obtained showed several interesting findings. The jet flow into the aneurysm led to complex vortex formation due to impinging flow behaviour within the aneurysm dome. Additionally, the area that recorded low velocity was at 30% of low TAWSS with only 1% of OSI that was more than 0.3, while the OSI critical value and 0.27% area exceeded RRT threshold, which caused the large oscillating blood flow direction and activated the atherosclerosis progression. These results suggest that the jet flow into the dome may cause further damage to the wall of the MCA aneurysm, which will help in providing an insight towards completing a guidance system assessment of rupture risk for medical practitioners in future work.
Cerebrovascular Model Equipped with Microsensors

Yoichi Haga, Hiroshi Yoshida, Tadao Matsunaga, Yasutomo Shimizu, Makoto Ohta, Masaaki Shojima, Taisuke Masuda, Kaihong Yu, Tupin Simon, Chenming Dai, Fumihito Arai, Kanako Harada

IEEJ Transactions on Sensors and Micromachines　140　(12)　354-362　2020/12/01
Publisher: Institute of Electrical Engineers of Japan ({IEE} Japan)
DOI： 10.1541/ieejsmas.140.354 　

ISSN：1347-5525
Epigenetic response of endothelial cells to different wall shear stress magnitudes: A report of new mechano-miRNAs. International-journal Peer-reviewed

Sherif Rashad, Xiaobo Han, Khalid Saqr, Simon Tupin, Makoto Ohta, Kuniyasu Niizuma, Teiji Tominaga

Journal of cellular physiology　235　(11)　7827-7839　2020/11

DOI： 10.1002/jcp.29436 　

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Endothelial cells (ECs) respond to flow stress via a variety of mechanisms, leading to various intracellular responses that can modulate the vessel wall and lead to diseases if the flow is disturbed. Mechano-microRNAs (miRNAs) are a subset of miRNAs in the ECs that are flow responsive. Mechano-miRNAs were shown to be related to atherosclerosis pathophysiology, and a number of them were identified as pathologic. Here, we exposed human carotid ECs to different wall shear stresses (WSS), high and low, and evaluated the response of miRNAs by microarray and quantitative polymerase chain reaction analysis. We discovered five new mechano-miRNAs that were not reported in that context previously to the best of our knowledge. Moreover, functional pathway analysis revealed that under low WSS conditions, several pathways regulating apoptosis are affected. In addition, KLF2 and KLF4, known atheroprotective genes, were downregulated under low WSS and upregulated under high WSS. KLF2 and VCAM1, both angiogenic, were upregulated under high WSS. NOS3, which is vascular protective, was also upregulated with higher WSS. On the contrary, ICAM-1 and E-selectin, both atherogenic and proinflammatory, were upregulated with high WSS. Collectively, the epigenetic landscape with the gene expression analysis reveals that low WSS is associated with a proapoptotic state, while high WSS is associated with a proliferative and proinflammatory state.
Hemodynamic-Based Evaluation on Thrombosis Risk of Fusiform Coronary Artery Aneurysms Using Computational Fluid Dynamic Simulation Method

Haoran Wang, Hitomi Anzai, Youjun Liu, Aike Qiao, Jinsheng Xie, Makoto Ohta, Zhihan Lv

Complexity　2020　2020/10/20
Publisher: WILEY-HINDAWI
DOI： 10.1155/2020/8507273 　

ISSN：1076-2787

eISSN：1099-0526

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Coronary artery aneurysms (CAAs) have been reported to associate with an increased risk for thrombosis. Distinct to the brain aneurysm, which can cause a rupture, CAA's threat is more about its potential to induce thrombosis, leading to myocardial infarction. Case reports suggest that thrombosis risk varied with the different CAA diameters and hemodynamics effects (usually wall shear stress (WSS), oscillatory shear index (OSI), and relative residence time (RRT)) may relate to the thrombosis risk. However, currently, due to the rareness of the disease, there is limited knowledge of the hemodynamics effects of CAA. The aim of the study was to estimate the relationship between hemodynamic effects and different diameters of CAAs. Computational fluid dynamics (CFD) provides a noninvasive means of hemodynamic research. Four three-dimensional models were constructed, representing coronary arteries with a normal diameter (1x) and CAAs with diameters two (2x), three (3x), and five times (5x) that of the normal diameter. A lumped parameter model (LPM) which can capture the feature of coronary blood flow supplied the boundary conditions. WSS in the aneurysm decreased 97.7% apparently from 3.51 Pa (1x) to 0.08 Pa (5x). OSI and RRT in the aneurysm were increased apparently by two orders of magnitude from 0.01 (1x) to 0.30 (5x), and from 0.38 Pa-1 (1x) to 51.59 Pa-1 (5x), separately. Changes in the local volume of the CAA resulted in dramatic changes in local hemodynamic parameters. The findings demonstrated that thrombosis risk increased with increasing diameter and was strongly exacerbated at larger diameters of CAA. The 2x model exhibited the lowest thrombosis risk among the models, suggesting the low-damage (medication) treatment may work. High-damage (surgery) treatment may need to be considered when CAA diameter is 3 times or higher. This diameter classification method may be a good example for constructing a more complex hemodynamic-based risk stratification method and could support clinical decision-making in the assessment of CAA.
Physiologic blood flow is turbulent. International-journal

Khalid M Saqr, Simon Tupin, Sherif Rashad, Toshiki Endo, Kuniyasu Niizuma, Teiji Tominaga, Makoto Ohta

Scientific reports　10　(1)　15492-15492　2020/09/23

DOI： 10.1038/s41598-020-72309-8 　

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Contemporary paradigm of peripheral and intracranial vascular hemodynamics considers physiologic blood flow to be laminar. Transition to turbulence is considered as a driving factor for numerous diseases such as atherosclerosis, stenosis and aneurysm. Recently, turbulent flow patterns were detected in intracranial aneurysm at Reynolds number below 400 both in vitro and in silico. Blood flow is multiharmonic with considerable frequency spectra and its transition to turbulence cannot be characterized by the current transition theory of monoharmonic pulsatile flow. Thus, we decided to explore the origins of such long-standing assumption of physiologic blood flow laminarity. Here, we hypothesize that the inherited dynamics of blood flow in main arteries dictate the existence of turbulence in physiologic conditions. To illustrate our hypothesis, we have used methods and tools from chaos theory, hydrodynamic stability theory and fluid dynamics to explore the existence of turbulence in physiologic blood flow. Our investigation shows that blood flow, both as described by the Navier-Stokes equation and in vivo, exhibits three major characteristics of turbulence. Womersley's exact solution of the Navier-Stokes equation has been used with the flow waveforms from HaeMod database, to offer reproducible evidence for our findings, as well as evidence from Doppler ultrasound measurements from healthy volunteers who are some of the authors. We evidently show that physiologic blood flow is: (1) sensitive to initial conditions, (2) in global hydrodynamic instability and (3) undergoes kinetic energy cascade of non-Kolmogorov type. We propose a novel modification of the theory of vascular hemodynamics that calls for rethinking the hemodynamic-biologic links that govern physiologic and pathologic processes.
Effects of wall compliance on multiharmonic pulsatile flow in idealized cerebral aneurysm models: comparative PIV experiments Peer-reviewed

Simon Tupin, Khalid M. Saqr, Makoto Ohta

Experiments in Fluids　61　(7)　2020/07
Publisher: Springer Science and Business Media {LLC}
DOI： 10.1007/s00348-020-02998-4 　
Preliminary Study of Eye-Tracking During the Coil Insertion Task in a Silastic Model of Intracranial Aneurysms. International-journal Peer-reviewed

Masaaki Shojima, Yoshihiro Okamoto, Makoto Ohta, Kuniyasu Niizuma, Nobuyuki Sakai, Teiji Tominaga

World neurosurgery　139　e827-e835　2020/07

DOI： 10.1016/j.wneu.2020.05.012 　

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OBJECTIVE: Surgical skills are generally acquired by watching the "hand movements" of experts. "Eye movements" are now attracting attention in skill-learning fields. Eye-tracking technology was introduced preliminarily to develop a better skill-learning system for neuroendovascular treatments. METHODS: During a task to place a detachable coil into a silastic cerebral aneurysm model under biplane X-ray fluoroscopy, gaze points were recorded using a head-mount eye-tracking device. RESULTS: During the task, 91% of fixations were allocated to the monitor displaying fluoroscopic images, and the others to the hands of operators or unspecified visual targets. More than 80% of fixations were located in frontal or lateral fluoroscopic images. Fixations were placed more frequently around the aneurysm than the microcatheter. One operator failed to recognize the timing when the proximal marker of the coil overlapped that of the microcatheter. The subject allocated most fixations to the frontal fluoroscopic image, whereas other subjects placed most fixations to the lateral fluoroscopic image. Furthermore, that operator put no fixations to the proximal marker of the microcatheter. CONCLUSIONS: The results of this preliminary study imply the feasibility of the eye tracking-based learning system for neuroendovascular treatments. The eye-tracking analysis has potential in investigating or preventing procedural failures in neuroendovascular treatments.
Haemodynamics in a patient-specific intracranial aneurysm according to experimental and numerical approaches: A comparison of PIV, CFD and PC-MRI. International-journal

Yujie Li, Yuuya Yoneyama, Haruo Isoda, Masaki Terada, Takafumi Kosugi, Takashi Kosugi, Mingzi Zhang, Makoto Ohta

Technology and health care : official journal of the European Society for Engineering and Medicine　29　(2)　253-267　2020/06/19

DOI： 10.3233/THC-202252 　

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BACKGROUND: The haemodynamics determined by different approaches for studying fluid dynamics - i.e. computational fluid dynamics (CFD), particle image velocimetry (PIV), and phase-contrast magnetic resonance imaging (PC-MRI) - have rarely been thoroughly compared; nor have the factors that affect accuracy and precision in each method. As each method has its own advantages and limitations, this knowledge is important for future studies to be able to achieve valid analyses of fluid flows. OBJECTIVE: To gauge the capacity of these methods for analysing aneurysmal flows, we compared the haemodynamic behaviours determined by each method within a patient-specific aneurysm model. METHODS: An in vitro silicone aneurysm model was fabricated for PIV and PC-MRI, and an in silico aneurysm model with the same geometry was reconstructed for CFD. With the same fluid model prepared numerically and physically, CFD, PIV and PC-MRI were performed to study aneurysmal haemodynamics. RESULTS: 2D velocity vectors and magnitudes show good agreement between PIV and CFD, and 3D flow patterns show good similarity between PC-MRI and CFD. CONCLUSIONS: These findings give confidence to future haemodynamic studies using CFD technology. For the first time, the morphological inconsistency between the PCMRI model and others is found to affect the measurement of local flow patterns.
What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review. International-journal Peer-reviewed

Khalid M Saqr, Sherif Rashad, Simon Tupin, Kuniyasu Niizuma, Tamer Hassan, Teiji Tominaga, Makoto Ohta

Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism　40　(5)　1021-1039　2020/05

DOI： 10.1177/0271678X19854640 　

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Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier-Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.
A Hemodynamic-Based Evaluation of Applying Different Types of Coronary Artery Bypass Grafts to Coronary Artery Aneurysms

Wang, H., Wang, H., Anzai, H., Liu, Y., Qiao, A., Xie, J., Ohta, M., Ohta, M., Ohta, M.

Complexity　2020　2020
Publisher: WILEY-HINDAWI
DOI： 10.1155/2020/9359340 　

ISSN：1076-2787

eISSN：1099-0526

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Coronary artery bypass grafts (CABGs), including saphenous vein grafts (SVGs) or left internal mammary artery (LIMA) grafts, are recently applied to treat coronary artery aneurysm (CAA). Surgical outcomes are considered to be related to surgical strategies (types of the bypass graft and whether CAA ligated or not) and the size of the CAA (usually characterized by diameter). However, the understanding of the relationship between the surgical outcomes and the abovementioned factors is limited. Previous studies related to CABG treatments have shown hemodynamic studies could help evaluate surgical outcomes through graft mass flow rate, wall shear stress (WSS), and oscillatory shear index (OSI). It is believed that the hemodynamic study of applying CABGs to CAA, which is not studied yet, could help us understand the different CABG surgeries. The aim of the study was to evaluate the hemodynamic differences among different surgical methods. To do this, eight three-dimensional models were constructed, representing application of SVGs and LIMA grafts to CAAs (whether ligated or not) with diameters two, three, and five times the normal diameter, to perform computational fluid dynamics (CFD) simulation. The lumped-parameter model (LPM) was coupled to the boundary of the 3D models which increase the complexity of the simulation, but it can ensure the stability of the simulation boundary conditions. The results show that SVG (no matter whether ligated or not) hemodynamic characteristics are positive, with an average high graft mass flow rate of 70 ml/min, an average WSS of 0.479 Pa, and a low OSI of 0.001. LIMA with CAA ligation has the same characteristics with higher WSS (average 1.701 Pa). The hemodynamic characteristics of LIMA without CAA ligation are negative, including high reverse mass flow rate and high OSI (0.367). The results indicate that the surgical outcomes of LIMA with CAA ligation are likely to be the best among these models. The surgical outcomes of LIMA without CAA ligation seem to be undesirable due to the high reverse mass flow and high OSI. The CAA diameter may not have a significant effect on surgical outcomes.
Development of a stereo dip-coating system for fabrication of tube-shaped blood vessel models International-journal

Shimizu, Y., Tupin, S., Kiyomitsu, C., Kitamura, K., Takashima, K., Ohta, M.

Scientific Reports　10　(1)　6929-6929　2020
Publisher: Springer Science and Business Media {LLC}
DOI： 10.1038/s41598-020-63718-w 　

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Tube-shaped blood vessel models that mimic their geometries and mechanical properties can deliver reliable and realistic behavioral information such as deformation and rupture during procedures such as insertion of medical devices. Thickness of vessel walls is an important parameter for fabricating the blood vessel models owing to their strong influence on the model behavior, especially during deformation. The dip-coating method is used to fabricate blood vessel models; however, non-uniform wall thicknesses are observed using this method. This study aimed at finding the characteristics of stereo "angular control dip-coating" (ACDC) system to develop a dip-coating system that can produce tubular models with uniformed wall thickness. The system developed here enables an observation of the substrate behavior from two different views. The conditions of dip-coating used in this study produce 1.36-1.82 mm in the maximum and 0.188-0.435 mm in minimum wall thickness and the fabricated walls cover the realistic range of carotid arterial dimensions. The characteristics of the ACDC system indicate that ACDC is effective for fabricating the uniform wall thickness particularly in the strong curved parts.
Assessing porous media permeability in non-Darcy flow: A re-evaluation based on the Forchheimer equation International-journal

Tupin, S., Ohta, M.

Materials　13　(11)　2535-2535　2020
Publisher: {MDPI} {AG}
DOI： 10.3390/ma13112535 　

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In a recent paper published in Materials (Castro et al., 2019), the permeability evaluation of triple periodic minimum surface samples was carried out experimentally. Darcy's law was used under unsuitable conditions, resulting in an underestimation of the results. In this comment, we highlight the problem and propose a new estimation of the permeability using the Forchheimer equation, which is better suited to the experimental conditions.
Preliminary study of eye tracking to investigate the differences in gaze behaviors depending on the experience of neuroendovascular therapy. International-journal

Masaaki Shojima, Yoshihiro Okamoto, Kuniyasu Niizuma, Makoto Ohta, Osamu Ishikawa, Ayano Fujisawa, Hiroyuki Tsukihara, Nobuyuki Sakai, Teiji Tominaga

Surgical neurology international　11　351-351　2020

DOI： 10.25259/SNI_543_2020 　

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Background: Neuroendovascular therapy is now the choice for the management of many neurovascular pathologies, and physicians with endovascular skills are in high demand. In addition to the traditional method of practicing hand movements to learn skills, a new strategy of practicing eye movements to learn skills is also attracting attention. This preliminary study explored the differences in gaze behavior depending on experience with endovascular procedures to be facilitated in future skill training in neuroendovascular therapy. Methods: Four physicians with experience of 3-412 neuroendovascular procedures wore eye-tracking devices during coil embolization of swine cervical arteries. Gaze metrics with direct correlations to the expertise of endovascular procedures were explored. Results: Gaze metrics with a positive direct correlation to experience included the proportion of fixation durations (PFD) in the screen area and the native images. Those with a negative direct correlation included the PFD in the off-screen area and the roadmap images and the average fixation durations in the off-screen and coil areas. During the parent artery occlusion procedure with detachable coils, more experienced operators preferred to look at native images rather than roadmap images and that less experienced operators tended to look down at their hands more frequently. Conclusion: This preliminary study demonstrated the feasibility of eye tracking to identify the differences in gaze behavior depending on the experience of endovascular procedures and may guide future eye-tracking studies in neuroendovascular therapy.
Endothelial cell distributions and migration under conditions of flow shear stress around a stent wire. International-journal Peer-reviewed

Hitomi Anzai, Tomohito Watanabe, Xiaobo Han, Narendra Kurnia Putra, Zi Wang, Hisatoshi Kobayashi, Makoto Ohta

Technology and health care : official journal of the European Society for Engineering and Medicine　28　(4)　345-354　2020

DOI： 10.3233/THC-191911 　

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BACKGROUND: Blood vessels are constantly exposed to flow-induced stresses, and endothelial cells (ECs) respond to these stresses in various ways. OBJECTIVE: In order to facilitate endothelialization after endovascular implantation, cell behaviors around a metallic wire using a flow circulation system are observed. METHODS: A parallel flow chamber was designed to reproduce constant shear stresses (SSs) on cell surfaces and to examine the effects of a straight bare metal wire on cell monolayers. Cells were then exposed to flow for 24 h under SS conditions of 1, 2, and 3 Pa. Subsequently, cell distributions were observed on the plate of the flow chamber and on the surface of the bare metal wire. Flow fields inside the flow chamber were analyzed using computational fluid dynamics under each SS condition. RESULTS: After 24 h, ECs on the bottom plate were concentrated toward the area of flow reattachment. The matching of higher cell density and CFD result suggests that flow-induced stimuli have an influence on EC distributions. CONCLUSION: Typical cell concentration occurs on dish plate along the vortexes, which produces large changes in SSs on cell layer.
脳動脈瘤コイル留置のシミュレーション手法と応用例

高嶋一登, 当麻直樹, 太田信, 森浩二

脳血管内治療　4　(Suppl.)　S19-S19　2019/11
Publisher: (NPO)日本脳神経血管内治療学会
ISSN：2423-9119

eISSN：2424-1709
脳動脈瘤コイル留置のシミュレーション目的と課題

当麻直樹, 高嶋一登, 太田信, 森浩二

脳血管内治療　4　(Suppl.)　S19-S19　2019/11
Publisher: (NPO)日本脳神経血管内治療学会
ISSN：2423-9119

eISSN：2424-1709
Pulse-Wave-Pattern Classification with a Convolutional Neural Network. International-journal Peer-reviewed

Gaoyang Li, Kazuhiro Watanabe, Hitomi Anzai, Xiaorui Song, Aike Qiao, Makoto Ohta

Scientific reports　9　(1)　14930-14930　2019/10/17
Publisher: Springer Science and Business Media {LLC}
DOI： 10.1038/s41598-019-51334-2 　

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Owing to the diversity of pulse-wave morphology, pulse-based diagnosis is difficult, especially pulse-wave-pattern classification (PWPC). A powerful method for PWPC is a convolutional neural network (CNN). It outperforms conventional methods in pattern classification due to extracting informative abstraction and features. For previous PWPC criteria, the relationship between pulse and disease types is not clear. In order to improve the clinical practicability, there is a need for a CNN model to find the one-to-one correspondence between pulse pattern and disease categories. In this study, five cardiovascular diseases (CVD) and complications were extracted from medical records as classification criteria to build pulse data set 1. Four physiological parameters closely related to the selected diseases were also extracted as classification criteria to build data set 2. An optimized CNN model with stronger feature extraction capability for pulse signals was proposed, which achieved PWPC with 95% accuracy in data set 1 and 89% accuracy in data set 2. It demonstrated that pulse waves are the result of multiple physiological parameters. There are limitations when using a single physiological parameter to characterise the overall pulse pattern. The proposed CNN model can achieve high accuracy of PWPC while using CVD and complication categories as classification criteria.
脳動脈瘤コイル塞栓術における術者の視線計測

岡本吉弘, 庄島正明, 新妻邦泰, 太田信, 植松美幸, 迫田秀行, 配島由二

人工臓器　48　(2)　S-224　2019/10
Publisher: (一社)日本人工臓器学会
ISSN：0300-0818

eISSN：1883-6097
Effect of a notch at the distal end of a microcatheter on vein deformation in segmental adrenal venous sampling: a preliminary study using computational fluid dynamics. International-journal Peer-reviewed

Tomo Kinoshita, Kazumasa Seiji, Narendra Kurnia Putra, Tomohito Watanabe, Sho Matsumoto, Makoto Ohta, Kei Takase

Medical & biological engineering & computing　57　(7)　1425-1436　2019/07

DOI： 10.1007/s11517-019-01968-1 　

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This study aimed to evaluate the effect of a notch at the distal end of a microcatheter on vein deformation in segmental adrenal venous sampling. A three-dimensional fluid-structure interaction simulation was performed using commercial finite element software. A computational model of a vein with a catheter inserted into it was constructed. The outer and inner diameters of the vein were 0.9 mm and 0.6 mm, respectively, whereas those of the catheter were 0.6 mm and 0.5 mm, respectively. The velocity of the blood flow at the outlet was 85 mm/s. The pressure at the inlet was 0 Pa. The mesh consisted of approximately 660,000 elements. The effect of the number (0-4) and shape (no notch, 1/4 circular, 1/3 circular, semicircular, 2/3 circlecircular, and 3/4 circular) of the notches at the distal end of the microcatheter on the vein deformation when a suction pressure was applied was evaluated. The venous wall displacement was the smallest with the one-notch catheter, followed by the four-notch catheter, and was the smallest with the catheter having 1/4-circular notches, followed by the one with 1/3-circular notches. In conclusion, microcatheters having one notch and 1/4-circular notches reduce vein deformation and lead to successful segmental adrenal venous sampling. Graphical abstract Comparing catheters having different notch shapes.
実体血管モデルを用いたコイルの接触面積・荷重の評価

池田雄太, 高嶋一登, 葭仲潔, 于凱鴻, 太田信, 森浩二, 当麻直樹, 鈴木秀謙

日本バイオレオロジー学会誌(B&R)　33　(2)　105-105　2019/06
Publisher: (NPO)日本バイオレオロジー学会
ISSN：0913-4778

eISSN：2186-5663
Evidence for non-Newtonian behavior of intracranial blood flow from Doppler ultrasonography measurements. International-journal Peer-reviewed

Khalid M Saqr, Ossama Mansour, Simon Tupin, Tamer Hassan, Makoto Ohta

Medical & biological engineering & computing　57　(5)　1029-1036　2019/05

DOI： 10.1007/s11517-018-1926-9 　

ISSN：0140-0118

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Computational fluid dynamics (CFD) studies of intracranial hemodynamics often use Newtonian viscosity model to close the shear rate term in the Navier-Stokes equation. This is based on a commonly accepted hypothesis which state that non-Newtonian effects can be neglected in intracranial blood flow. This study aims to examine the validity of such hypothesis to guide future CFD studies of intracranial hemodynamics. Doppler ultrasonography (DUS) measurements of systolic and diastolic vessel diameter and blood velocity were conducted on 16 subjects (mean age 50.6). The measurements were conducted on the internal carotid (ICA), middle cerebral (MCA), and anterior communicating (AComA) arteries. Systolic and diastolic wall shear stress (WSS) values were calculated via the Hagen-Poiseuille exact solution using Newtonian and three different non-Newtonian models: namely Carreau, power-law and Herschel-Bulkley models. The Weissenberg-Rabinowitsch correction for blood shear-thinning viscosity was applied to the non-Newtonian models. The error percentage between the two sets of models was calculated and discussed. The Newtonian hypothesis was tested statistically and discussed using paired t tests. Significant differences (P < 0.0001) were found between the Newtonian and non-Newtonian WSS in ICA. In MCA and AComA, similar differences were found except in the systole and diastole for the Herschel-Bulkley and power-law models (P = 0.0669, P = 0.7298), respectively. The error between the Newtonian and non-Newtonian models ranged from - 27 to 30% (0.2 to 2.2 Pa). These values could affect the physical interpretation of IA CFD studies. Evidence suggests that the Newtonian assumption may be inappropriate to investigate intracranial hemodynamics. Graphical abstract The WSS estimation error resulting from using the Newtonian assumption compared to three non-Newtonian models for ICA, MCA, and AComA in systole and diastole conditions, based on TCCD measurements of 16 subjects. The error due to the Newtonian assumption ranged from 0.2 to 2.2 Pa (- 27 to 30%). These values could affect the physical interpretation of IA CFD studies.
Influence of TGF-β1 expression in endothelial cells on smooth muscle cell phenotypes and MMP production under shear stress in a co-culture model. International-journal Peer-reviewed

Xiaobo Han, Naoya Sakamoto, Noriko Tomita, Hui Meng, Masaaki Sato, Makoto Ohta

Cytotechnology　71　(2)　489-496　2019/04

DOI： 10.1007/s10616-018-0268-7 　

ISSN：0920-9069

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Recently, our group has contrasted an endothelial cell-smooth muscle cell (EC-SMC) co-culture model with 3D-cultured SMCs and found that SMCs could respond to high shear stress (SS), which has not been explored before. SMCs were not directly exposed to the flow but were under an EC monolayer; therefore, it is necessary to explore the influence of EC on SMC behaviors under high SS for understanding the mechanism of SMC response to various magnitudes of SS. In the present study, TGF-β1 expression in ECs in an EC-SMC co-culture model was suppressed by an siRNA transfection method. Next, phenotypic changes were observed and MMP-2 and -9 productions were measured in SMCs in the co-culture model after 72-h flow exposure to different SS levels. We confirmed that TGF-β1 expression in ECs could influence SMC phenotypic change under SS conditions and that TGF-β1 expression in ECs could also change MMP-2 production but not MMP-9 production in SMCs under SS conditions in the co-culture model. These results could be useful for understanding the mechanisms of SMC response to SS, particularly for understanding signal transduction emanating from ECs.
Effects of Elasticity on Wall Shear Stress in Patient-Specific Aneurysm of Cerebral Artery Peer-reviewed

Ryuhei Yamaguchi, Taihei Kotani, Gaku Tanaka, Simon Tupin, Kahar Osman, Nadia Shaira Shafii, Ahmad Zahran, Md Khudzari, Kazuhiro Watanabe, Hitomi Anzai, Atsushi Saito, Makoto Ohta

Journal of Flow Control, Measurement & Visualization　7　(2)　73-86　2019/02
Systematic review of hemodynamic discriminators for ruptured intracranial aneurysms Peer-reviewed

Yagi Takanobu, Okamoto Yoshihiro, Ohta Makoto, Nakamura Masanori, on behalf of the CFD-BIO study group, Ishida Fujimaro, Shojima Masaaki, Anzai Hitomi, Fujimura Souichiro, Sano Takanori, Shinozaki Shun, Yamanaka Yuuma, Yamamoto Yuuto

Journal of Biorheology　33　(2)　53-64　2019
Publisher: JAPANESE SOCIETY OF BIORHEOLOGY
DOI： 10.17106/jbr.33.53 　

ISSN：1867-0466

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Researchers have aimed to identify unruptured intracranial aneurysms at a higher risk of rupture during follow-up for a long time. Computational fluid dynamics has been used widely to identify a hemodynamic discriminator between ruptured and unruptured aneurysms. However, this method has yet to reach a consensus between groups, which may be due, in part, to the significant degrees of freedom in hemodynamic indexes and computational workflows. The present review aims to characterize the degree of association between ruptured aneurysms and hemodynamic indexes, as well as the degree of variability between groups. A PubMed search identified 588 relevant studies. Thirteen met our criteria, yielding a total of 3,692 aneurysms. The definition of hemodynamic indexes were first carefully assessed and then classified accordingly. The variability of hemodynamic indexes between groups displayed a significant index-dependent nature. Normalizing hemodynamic indexes was an effective measure of reducing variability. Hemodynamic indexes were evaluated for associability and quantifiability. Overall, in an attempt to advance the diagnostic performance of hemodynamic indexes, these results shed light on the poor ability to interpret hemodynamic states pathologically. Future studies should incorporate the pathological significance of hemodynamic states into the design of hemodynamic indexes.
Bionic Humanoid – Current status and direction of blood vessel model Peer-reviewed

Systems, Control and Informations　63　(10)　415-419　2019
The effect of contact force during radiofrequency catheter ablation using a vibrating catheter: New cooling method for catheter ablation. International-journal Peer-reviewed

Kaihong Yu, Tetsui Yamashita, Shigeaki Shingyochi, Kazuo Matsumoto, Atsuki Komiya, Makoto Ohta

Technology and health care : official journal of the European Society for Engineering and Medicine　27　(6)　589-601　2019

DOI： 10.3233/THC-191639 　

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BACKGROUND: A new cooling method is proposed for preventing electrode-tissue overheating during cardiac catheter ablation using a vibrating catheter. Previous work has shown that vibration that results from increased flow velocity around the catheter can have a cooling effect on the electrode. OBJECTIVE: Contact force has been shown to be an important factor that affects cooling and lesion formation, because contact force determines the ratio of power delivery between blood and tissue. In this study, the effect of contact force on electrode cooling and tissue heating was investigated during the operation of an electrode cooled by vibration. METHODS: Using PVA-H or myocardium ablation tissue models under conditions of no flow, electrode and tissue temperatures and lesion sizes were measured at various vibrational frequencies and contact force conditions. RESULTS: The experiments showed that the catheter vibration still decreases the electrode temperature over a contact force range of 2-30 gf. The lesion size was increased with increasing contact force at each vibrational frequency. CONCLUSIONS: Increasing contact force can increase lesion size with cooling by vibration remaining effective.
Multiobjective design optimization of stent geometry with wall deformation for triangular and rectangular struts. International-journal Peer-reviewed

Narendra Kurnia Putra, Pramudita Satria Palar, Hitomi Anzai, Koji Shimoyama, Makoto Ohta

Medical & biological engineering & computing　57　(1)　15-26　2019/01

DOI： 10.1007/s11517-018-1864-6 　

ISSN：0140-0118

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The stent geometrical design (e.g., inter-strut gap, length, and strut cross-section) is responsible for stent-vessel contact problems and changes in the blood flow. These changes are crucial for causing some intravascular abnormalities such as vessel wall injury and restenosis. Therefore, structural optimization of stent design is necessary to find the optimal stent geometry design. In this study, we performed a multiobjective stent optimization for minimization of average stress and low wall shear stress ratio while considering the wall deformation in 3D flow simulations of triangular and rectangular struts. Surrogate-based optimization with Kriging method and expected hypervolume improvement (EHVI) are performed to construct the surrogate model map and find the best configuration of inter-strut gap (G) and side length (SL). In light of the results, G-SL configurations of 2.81-0.39 and 3.00-0.43 mm are suggested as the best configuration for rectangular and triangular struts, respectively. Moreover, considering the surrogate model and flow pattern conditions, we concluded that triangular struts work better to improve the intravascular hemodynamics. ᅟ Graphical abstract.
Viscosity measurement of Xanthan-Poly(vinyl alcohol) mixture and its effect on the mechanical properties of the hydrogel for 3D modeling. International-journal Peer-reviewed

Yasutomo Shimizu, Tadao Tanabe, Hiroshi Yoshida, Motohiro Kasuya, Tadao Matsunaga, Yoichi Haga, Kazue Kurihara, Makoto Ohta

Scientific reports　8　(1)　16538-16538　2018/11/08

DOI： 10.1038/s41598-018-34986-4 　

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Biomodels made of poly(vinyl alcohol) (PVA) are demanded because they can represent the geometries and mechanical properties of human tissues realistically. Injecting and molding, commonly used in three-dimensional (3D) modeling, help to represent the blood vessels accurately. However, these techniques sometimes require higher pressures than the upper pressure limit of the dispensers for pouring in high viscosity materials; the material viscosity should therefore be lower. Moreover, the mechanical properties of the biomodels should be reproduced. This study proposes a PVA solution through the addition of xanthan gum (XG) for 3D modeling, which lowers liquid viscosity while maintaining the mechanical properties of biomodels. XG is known to facilitate the achievement of non-Newtonian fluidity; however, the effects of XG on a PVA solution and PVA hydrogel (PVA-H) are not confirmed. The viscosity measurement using 15 wt% PVA with XG solution (PVA/XG) shows that it will provide easier pouring than 17 wt% PVA solution. The tensile test using the PVA-H of PVA(15 wt%)/XG(0.2 wt%) reveals that the gel is comparable in Young's modulus to 17 wt% PVA-H. X-ray diffraction shows the crystalline structures of the PVA/XG gel and PVA-H are identical. Thus, this PVA/XG would be useful for fabricating biomodels using injection molding techniques.
Numerical simulation of aneurysmal haemodynamics with calibrated porous-medium models of flow-diverting stents. International-journal Peer-reviewed

Yujie Li, Mingzi Zhang, David I Verrelli, Winston Chong, Makoto Ohta, Yi Qian

Journal of biomechanics　80　88-94　2018/10/26

DOI： 10.1016/j.jbiomech.2018.08.026 　

ISSN：0021-9290

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Modelling flow-diverting (FD) stents as porous media (PM) markedly improves the efficiency of computational fluid dynamics (CFD) simulations in the study of intracranial aneurysm treatment. Nonetheless, the parameters of PM models adopted for simulations up until now were rarely calibrated to match the represented FD structure. We therefore sought to evaluate the PM parameters for a representative variety of commercially available stents, so characterising the flow-diversion behaviours of different FD devices on the market. We generated fully-resolved geometries for treatments using PED, Silk+, FRED, and dual PED stents. We then correspondingly derived the calibrated PM parameters-permeability (k) and inertial resistance factor (C2)-for each stent design from CFD simulations, to ensure the calibrated PM model has identical flow resistance to the FD stent it represents. With each of the calibrated PM models respectively deployed in two aneurysms, we studied the flow-diversion effects of these stent configurations. This work for the first time reported several sets of parameters for PM models, which is vital to address the current knowledge gap and rectify the errors in PM model simulations, thereby setting right the modelling protocol for future studies using PM models. The flow resistance parameters were strongly affected by porosity and effective thickness of the commercial stents, and thus accounted for in the PM models. Flow simulations using the PM stent models revealed differences in aneurysmal mass flowrate (MFR) and energy loss (EL) between various stent designs. This study improves the practicability of FD simulation by using calibrated PM models, providing an individualised method with improved simulation efficiency and accuracy.
Structural Design and Numerical Analysis of a Novel Biodegradable Zinc Alloy Stent

Kun Peng, Aike Qiao, Makoto Ohta, Narendra Kurnia Putra, Xinyang Cui, Yongliang Mu, Hitomi Anzai

CMES-COMPUTER MODELING IN ENGINEERING & SCIENCES　117　(1)　17-28　2018/10
Publisher: TECH SCIENCE PRESS
DOI： 10.31614/cmes.2018.04113 　

ISSN：1526-1492

eISSN：1526-1506

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Biodegradable zinc alloy stents are a prospective solution for complications caused by the incompatibility between artery and permanent stents. However, insufficient scaffolding has limited the clinical application of biodegradable zinc alloy stents. Therefore, in this study, a new stent concept was designed to improve the scaffolding. The mechanical performances of the new and a traditional design stent were investigated and compared using finite element analysis (FEA). The new and traditional design stent were expanded to the intended radial displacement of 0.24 mm under the expansion pressure of 0.58 MPa and 0.45 MPa, respectively. Then, a pressure load of 0.35 MPa was exerted on the outer surfaces of the two stents to compress them. The results showed that the radial recoiling ratio were 45.3% and 83.3% for the new and the traditional stent, respectively. The simulations demonstrate that the biodegradable zinc alloy stent offers enhanced support because of the new structural design. This study implies that biodegradable zinc alloy stent can be a new competitive intervention device for the future clinical cardiovascular application.
Computational Fluid Dynamics Analysis to Predict Endothelial Cells Migration During Flow Exposure Experiment With Placement of Two Stent Wires. International-journal Peer-reviewed

Narendra Kurnia Putra, Zi Wang, Hitomi Anzai, Makoto Ohta

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference　2018　5454-5457　2018/07

DOI： 10.1109/EMBC.2018.8513517 　

ISSN：1557-170X

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Stent deployment is currently used for many cardiovascular treatments. During its application, the presence of the stent inside the blood vessel will indeed cause some change in both flow environment and also vessel wall's cellular conditions. This research intends to learn about the flow phenomenon of how vessel wall endothelial cells (ECs) react to the presence of stent wires within a microfluidic flow chamber environment. Computational fluid dynamics (CFD) simulation analysis of the microfluidic flow chamber system has been performed for observing the hemodynamics phenomena in the chamber. Moreover, CFD method also can be beneficial as a planning step for a successful experimental study. We found that under the two wires configurations, high wall shear stress (WSS) area is developed on the downstream side of the wires. Based on the analysis of WSS and WSS gradients (WSSG) conditions, ECs morphological change and migration are likely to occur some specific area.
Reproduction method for dried biomodels composed of poly (vinyl alcohol) hydrogels. International-journal Peer-reviewed

Yasutomo Shimizu, Narendra Kurnia Putra, Makoto Ohta

Scientific reports　8　(1)　5754-5754　2018/04/10

DOI： 10.1038/s41598-018-24235-z 　

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Models mimicking the realistic geometries and mechanical properties of human tissue are requiring ever-better materials. Biomodels made of poly (vinyl alcohol) are particularly in demand, as they can be used to realistically reproduce the characteristics of blood vessels. The reproducibility of biomodels can be altered due to dehydration that is observed after long periods of usage. In order to improve their usability, one should consider the method used to reproduce them; however, few studies have reported a method reproduce biomodels. This study proposes a novel reproduction method for biomodels that allows them to quickly and easily reproduce their geometric and mechanical properties. Specimens of the dried biomodels were reformed through immersion in temperature-controlled water. Our results show that water at 35 °C can be effective to reproduce both the geometric and mechanical properties of the specimens. X-ray diffraction (XRD) measurements revealed that water immersion can reform the crystal structure of the pre-dried specimens, and images obtained using micro-computed tomography acquisition show that the geometry of the specimens can be reformed by water immersion without introducing any defects. These results indicate that the proposed method can lead to high reproducibility of both the original geometric and mechanical properties of the dried biomodels.
Biomodel of Hard Tissue for Dynamic Mechanical Testing of Medical Devices International-coauthorship

Makoto Ohta, Dominik Huesener, Yuta Muramoto, Simon Tupin

The Reports of the Institute of Fluid Science, Tohoku University　29　11-20　2018/02
Pulse pattern classification of atherosclerotic patients based on convolutional neural network

Li Gaoyang, Anzai Hitomi, Watanabe Kazuhiro, Qiao Aike, Ohta Makoto

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2018.29　2C11　2018
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2018.29.2c11 　 10.1038/s41598-019-51334-2_references_DOI_DGABgnXW2V9ZPOSKNTUf6jSoCY6 　

eISSN：2424-2810

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Pulse wave contains a lot of cardiovascular diseases (CVD) information. It can be used as an early diagnostic method for CVD. Previous studies have shown that the pulse wave of atherosclerotic patients are significantly different from those of healthy subjects. In this study, we extracted 210 pulse wave cycles from atherosclerotic patients. At the same time, as a control group, we extracted the same number of pulse cycles from healthy subjects. An optimized convolution neural network (CNN) was proposed to classify these two pulse patterns. The proposed CNN had good performance with 95% accuracy on distinguishing arteriosclerosis vs non- arteriosclerosis. Our study showed that CNN could identify pulse waves in atherosclerosis patients with high accuracy. It could help to develop a non-invasive and efficient method for arteriosclerosis detection.
Simulation research on hemodynamic of surgery of coronary artery aneurysm

WANG Haoran, ANZAI Hitomi, LIU Youjun, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2018　J0210303　2018
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2018.j0210303 　

eISSN：2424-2667

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Coronary artery aneurysm (CAA) is an unusual disease whose incidence was reported as 0.14-4.9%. Currently, CAA usually is treated with coronary artery bypass grafting (CABG) surgery. However, there is limited evidence to prove which operation procedure, including bypass by saphenous vein graft (SVG) or left internal mammary artery (LIMA) with or without ligation of CAA, is better to treat this disease. At present, studies have shown that hemodynamic parameters are an important basis which can supply evidence to make the evaluation for different surgery. Therefore, we study the feasibility of different operating procedures from a hemodynamic point of view. Here we present four 3D models with coronary arteries and aortic arch named Model 1-4 (SVG/LIMA with CAA, SVG/LIMA without CAA, respectively). In order to reduce the computational requirements and obtain good boundary conditions, lumped parameter model (LPM, 0D model) coupled with 3D models. The mass-flow of SVG and LIMA, wall shear stress (WSS) and oscillatory shear index (OSI) were evaluated. Normal WSS and low OSI in grafting region appeared in Model 1, 3, and 4. Inverse flow, normal WSS, and high OSI put in an appearance on the LIMA in Model 2. Based on previous work, inverse graft flow and high OSI can make bypass graft invalid. Therefore, from a hemodynamic point of view, SVG and LIMA both can be used as the bypass graft to treat the CAA. However, CAA should be ligated when LIMA is used.
Research on arterial stiffness status in type 2 diabetic patients based on pulse waveform characteristics

Li, G., Song, X., Qiao, A., Ohta, M.

CMES - Computer Modeling in Engineering and Sciences　117　(2)　2018

DOI： 10.31614/cmes.2018.04100 　
EXPERIMENTAL ANALYSIS FOR THE ANISOTROPIC FLOWS IN CANCELLOUS BONE Peer-reviewed

Ito, Makoto, Tupin, Simon, Anzai, Hitomi, Suzuki, Anna, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2017, Vol 3　2018
Effects of Pulsatile Inlet Conditions on the Hemodynamic Conditions of Stent with Deformed Wall Simulation Peer-reviewed

Narendra Kurnia Putra, Hitomi Anzai, Makoto Ohta

Proceedings of the 5th international Conference on Instrumentation, Communications, Information Technology and Biomedical Engineering (ICICI-BME 2017)　57-61　2017/11/06
Publisher: IEEE
ISSN：2158-0456

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Human blood Ilow is naturally working as a pulsatile flow under the influence of heartbeat cycle. As many blood flow simulation studies have been conducted recently, many assumption and simplification of intravascular flow phenomena were used as the boundary condition of the simulation. For example, stent contact rigid wall condition, steady blood tlow also material simple models and properties of tissues and blood. However, these simplifications may lead to inaccuracy of the results and analysis. This paper tries to observe the simulation results from different boundary conditions which include the pulsatile flow conditions and how it behaves compared to the steady flow. From the investigation and comparison, the difference between results of flow parameters obtained from the pulsatile and steady simulation shows 2.2% deviation on the appearance of low WSS along the deployment area.
Stent design optimization based on kriging surrogate model under deformed vessel wall: Pulsatile inlet flow Peer-reviewed

Narendra Kurnia Putra, Pramudita Satria Palar, Hitomi Anzai, Koji Shimoyama, Makoto Ohta

Proceedings of the 2017 5th International Conference on Instrumentation, Control, and Automation, ICA 2017　172-176　2017/10/13
Publisher: Institute of Electrical and Electronics Engineers Inc.
DOI： 10.1109/ICA.2017.8068435 　

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The cardiovascular stent is one of the medical devices which has been commonly used for curing many vascular diseases. Nowadays, research on many aspects of stent development has been conducted to improve the device's efficacy. Mechanical and flow dynamics analysis on stent performance are useful to understand the impact of the device deployment. Many assumptions have been applied for constructing the stent simulation model including the blood vessel wall condition and its inlet flow conditions. Recently, common assumptions of the stent simulation model are mainly worked under the assumption of rigid wall condition and steady or pulsatile inlet flow. These different assumptions may lead to different simulation results. These differences may also affect the further analysis such as optimization process. This research tries to investigate the pulsatile effect on the stent optimization results based on computational simulation with wall deformation. Comparison with the previous optimization with a steady flow was conducted to find out about the differences between the two conditions. We found that the difference in optimization results from both inflow conditions is insignificant.
In search for a better stent: Surrogate based multi-objective optimization of stent design under influence of vessel wall deformation. International-journal Peer-reviewed

Narendra Kurnia Putra, Pramudita Satria Palar, Hitomi Anzai, Koji Shimoyama, Makoto Ohta

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference　2017　1344-1347　2017/07

DOI： 10.1109/EMBC.2017.8037081 　

ISSN：1557-170X

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Stenting is known as one of the main treatment procedure for some intravascular abnormalities such as stenosis and aneurysm. In recent years, stent optimization has been conducted by several research groups in order to increase its treatment efficacy. If we can observe post-deployment behavior on the blood vessel with respect to different stent designs, this observation will be useful in the design process. Kriging surrogate model based on fluid flow simulation on a deformed vessel wall was developed in order to observe this behavior. Multi-objectives optimization was performed with configurations of gap and size as design variables. In this research, percentage of low wall shear stress (WSS) area and average mechanical stress along the deployment area were set as the objective functions. We can recommend that strut with medium size around 100 - 250 micron with a relatively big inter-strut gap is suitable for achieving the optimize criteria. This is because on this range, acceptable optimized value of both objectives functions are successfully obtained.
Applying computer simulation to the design of flow-diversion treatment for intracranial aneurysms. International-journal Peer-reviewed

Mingzi Zhang, Yujie Li, David I Verrelli, Winston Chong, Makoto Ohta, Yi Qian

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference　2017　3385-3388　2017/07

DOI： 10.1109/EMBC.2017.8037582 　

ISSN：1557-170X

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Although flow-diversion (FD) treatment has been proven to be able to induce intracranial aneurysm (IA) occlusion, clinical follow-ups reported that a number of patients may still suffer from delayed IA rupture or incomplete aneurysm occlusion post-treatment. Complete aneurysm occlusion is believed to be associated with favourable haemodynamic alteration post-treatment, which may be greatly affected by the selection of device size and quantity, as well as the FD deployment procedure. However, clinicians have to choose and deploy the FD relying on their experience, since no post-stenting haemodynamic information is generally available to them prior to a specific treatment. In this study, using a virtual FD deployment technique and computational fluid dynamics method, we demonstrate and compare the haemodynamic changes after virtual FD treatments using a variety of prospective treating strategies.
Sensitivity study on modelling a flow-diverting stent as a porous medium using computational fluid dynamics. International-journal Peer-reviewed

Yujie Li, Mingzi Zhang, David I Verrelli, William Yang, Winston Chong, Makoto Ohta, Yi Qian

Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual International Conference　2017　3389-3392　2017/07

DOI： 10.1109/EMBC.2017.8037583 　

ISSN：1557-170X

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The flow-diverting (FD) stent has become a commonly used endovascular device to treat cerebral aneurysms. This discourages blood from entering the aneurysm, thereby reducing the likelihood of aneurysm rupture. Using computational fluid dynamics (CFD) to simulate the aneurysmal haemodynamics after FD treatment could help clinicians predict the stent effectiveness prior to the real procedure in the patient. As an alternative to modelling the stent as a fine wire mesh, modelling the FD stent as a porous medium was established to save computational time, and has also been proved capable of predicting the same haemodynamics as obtained using the real FD stent geometry. The flow resistance effect of a porous-medium stent may differ with respect to its morphology or permeability; however, the flow resistance effect after adjusting these parameters had not been clarified. In this study, we analysed the haemodynamic changes caused by alterations of porous-medium thickness and permeability, thereby providing future porous-medium stent simulations with important information on the respective parametric sensitivities. We found significant sensitivity to permeability. Results were insensitive to thickness when permeability was adjusted beforehand to compensate. We also compared our results with observations from an in-vitro model, and found good agreement. This supports adoption of porous-medium models in future work.
Comparative Study between Different Strut’s Cross Section Shape on Minimizing Low Wall Shear Stress along Stent Vicinity via Surrogate-based Optimization Peer-reviewed

Narendra Kurnia Putra, Pramudita Satria Palar, Hitomi Anzai, Koji Shimoyama, Makoto Ohta

12th World Congress of Structural and Multidisciplinary Optimisation　2017/06/09
Haemodynamic effects of stent diameter and compaction ratio on flow-diversion treatment of intracranial aneurysms: A numerical study of a successful and an unsuccessful case International-journal Peer-reviewed

Mingzi Zhang, Yujie Li, Xi Zhao, David I. Verrelli, Winston Chong, Makoto Ohta, Yi Qian

JOURNAL OF BIOMECHANICS　58　179-186　2017/06
Publisher: ELSEVIER SCI LTD
DOI： 10.1016/j.jbiomech.2017.05.001 　

ISSN：0021-9290

eISSN：1873-2380

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Background: Compacting a flow-diverting (FD) stent is an emerging technique to create a denser configuration of wires across the aneurysm ostium. However, quantitative analyses of post-stenting haemodynamics affected by the compaction level of different stent sizes remain inconclusive.Objective: To compare the aneurysmal haemodynamic alterations after virtual FD treatments with different device diameters at different compaction ratios.Methods: We virtually implanted three sizes of FD stent, with each size deployed at four compaction ratios, into two patient aneurysms previously treated with the Silk + FD-one successful case and the other unsuccessful. Wire configurations of the FD in the 24 treatment scenarios were examined, and aneurysmal haemodynamic alterations were resolved by computational fluid dynamics (CFD) simulations. We investigated the aneurysmal flow patterns, aneurysmal average velocity (AAV), mass flowrate (MF), and energy loss (EL) in each scenario.Results: Compactions of the stent in the successful case resulted in a greater metal coverage rate than that achieved in the unsuccessful one. A 25% increment in compaction ratio further decreased the AAV (12%), MF (11%), and EL (9%) in both cases (average values). The averaged maximum differences attributable to device size were 10% (AAV), 8% (MF), and 9% (EL).Conclusions: Both stent size and compaction level could markedly affect the FD treatment outcomes. It is therefore important to individualise the treatment plan by selecting the optimal stent size and deployment procedure. CFD simulation can be used to investigate the treatment outcomes, thereby assisting doctors in choosing a favourable treatment plan. (C) 2017 Elsevier Ltd. All rights reserved.
Evaluation system for coil embolization of cerebral aneurysm using blood vessel model equipped with ultra-miniature fiber-optic pressure sensors

Osaki Soyaka, Matsunaga Tadao, Shimizu Yasutomo, Shouzima Masaaki, Yoshida Hiroshi, Tsuruoka Noriko, Ohta Makoto, Haga Yoichi

Transactions of Japanese Society for Medical and Biological Engineering　55　(4)　287-287　2017
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.55Annual.287 　

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In recent years, coil embolization of cerebral aneurysm has been widely performed as a method of endovascular treatment. Therapeutic effect tends to be insufficient when coils are placed in biased position in the aneurysm or blood flow in neck area is insufficiently reduced. It is considered that quantitative evaluation of therapeutic effect of coil embolization is important. Pressure changes before and after coil placement were measured by multipoint pressure measurement locally at the inside of the aneurysmal part and the vessel part near the aneurysm in the blood vessel model fabricated using PVA-H (Poly (Vinyl Alcohol) Hydrogel). Two ultra-miniature fiber-optic pressure sensors were inserted and located into the aneurysm from the outside of the model. Two commercially available pressure sensors were also connected to both upstream and downstream sides of the model, respectively. Pressure change in the aneurysm in accordance with the number of the coils could be measured. (137words)
Development of endovascular treatment environment for medical training and simulation using coiling

Shimizu Yasutomo, Tupin Simon, Yu Kaihong, Osaki Soyoka, Yoshida Hiroshi, Shojima Masaaki, Matsunaga Tadao, Haga Yoichi, Ohta Makoto

Transactions of Japanese Society for Medical and Biological Engineering　55　(4)　288-288　2017
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.55Annual.288 　

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Intravascular treatment is recognized as one of the most difficult skills to acquire for medical doctors and realistic in vitro training systems for endovascular treatment are increasingly demanded these days. Vessel model is a major part to construct the system with strong requirements of the reproducibility of both mechanical properties and haptic sense during catheter operation. In this study, the condition to fabricate realistic models and the training system imitating the environment of intravascular treatment were established and 4-coil occlusion in the aneurysmal model was performed by a skilled medical doctor. The coils are successfully inserted into the aneurysm and the doctor evaluates haptic sense during the operation is similar to realistic situations. The experimental result and the doctor's evaluation indicate the new developed system is beneficial to the training of intravascular treatment.
An Analysis on Evaluation structures of Blood Vessel Model by Medical Doctor Using Evaluation Grid Method

Yu Kaihong, Shimizu Yasutomo, Tupin Simon, Shojima Masaaki, Ohta Makoto

Transactions of Japanese Society for Medical and Biological Engineering　55　(4)　286-286　2017
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.55Annual.286 　

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Recently, with the increased popularity of endovascular therapy, blood vessel model become more important owing to its practicality in skill training and new device evaluation. To develop the appropriate model, it's necessary to understand how doctors evaluate the model. In this research, a doctor in NeuroEndovascular therapy was interviewed to analyze his evaluation structure of blood vessel. During the test, the doctor was asked to evaluate three different blood vessel models made based on a same realistic geometry of cerebral artery by using catheter. A sensory test methodology called evaluation grid method was used to analyze the evaluation structure of the doctor. Our results suggest that, the evaluation of a blood vessel model by a doctor is made based on the sensation given by the model through the catheter, including the friction of the inner wall, the similarity of the shape, and the confidence obtained by using the model.
The influence of TGF-β1 from ECs on SMC MMP-2 Production under Shear Stress in a Co-Culture Model

Han Xiaobo, Sakamoto Naoya, Tomita Noriko, Meng Hui, Sato Masaaki, Ohta Makoto

Transactions of Japanese Society for Medical and Biological Engineering　55　(5)　414-414　2017
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.55Annual.414 　

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In the present study, the author constructed an EC-SMC co-culture model with SMCs 3D cultured in a collagen gel, and SMCs phenotype was controlled into a contractile state. Then, different magnitudes of shear stress (SS) were applied to the co-culture model and the results showed that a high SS of 10 Pa could induce higher matrix metalloproteinases (MMPs) productions from SMC in the co-culture model. As to understand ECs influence on SMC responses, TGF-β1 (Transforming growth factor beta 1) expression from ECs were suppressed by an SiRNA transfection method in the present study. Compared to different MMP-2 production levels under different SS in the normal co-culture model, SMCs showed same MMP-2 production level under all SS conditions in the co-culture model with transfected ECs. This result means that TGF-β1 expression from ECs could influence SMCs response to SS in a co-culture model.
Response Surface based Analysis to Improve the Intravascular Stent Design Performance on Optimizing Wall Shear Stress Conditions

Putra Narendra Kurnia, Palar Pramudita Satria, Anzai Hitomi, Shimoyama Koji, Ohta Makoto

Transactions of Japanese Society for Medical and Biological Engineering　55　(5)　415-415　2017
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.55Annual.415 　

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Restenosis is known as common problem during stent treatment. Stent optimization has been introduced to find the best design criteria in order to improve the endovascular treatment efficacy. Surrogate method is known as efficient method of optimization that has been built up from finite element method (FEM) simulation. Besides obtaining the optimized criteria, response surface plot which constructed by Kriging surrogate estimation process is also beneficial to study the behavior of design variables towards objective functions. In this study, we constructed the response surface map from stent design parameter configuration of strut size and inter-strut gap towards objective function. Our objective function is to minimizing the percentage of low wall shear stress area along deployment region. With this response surface, broad analysis on the stent performance can be clearly observed. More recommendations on how combinations between stent strut's size and gap should be designed are successfully obtained by this study.
Development of in-vitro experimental devices for in-situ evaluation of hemodynamic effects induced by endovascular devices and their deployment

Tupin Simon, Anzai Hitomi, Ohta Makoto

Transactions of Japanese Society for Medical and Biological Engineering　55　(5)　416-416　2017
Publisher: Japanese Society for Medical and Biological Engineering
DOI： 10.11239/jsmbe.55Annual.416 　

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Endovascular devices are medical devices inserted into the arteries in case of aneurysm. This minimally invasive treatment is preferred in case of aged patient. The number of commercially available device designs increased on the market but no data exist regarding direct comparisons of their performance, difficult to perform in vivo. The purpose of this research is to create in vitro experimental platforms allowing the study of the influence of those medical devices by monitoring the hemodynamic changes occurred during their deployments. Precise multi-scale evaluation of pressure and flow rate into the arteries surrounding the aneurysm are performed and synchronized to each step of the medical procedure. Further analysis are also conducted on the geometry of the deployed devices and flow pattern changes after deployment. As a proof of concept, studies of the treatment of an abdominal aortic aneurysm and an intracranial aneurysm are presented.
Applying Computer Simulation to the Design of Flow-diversion Treatment for Intracranial Aneurysms

Mingzi Zhang, Yujie Li, David I. Verrelli, Winston Chong, Makoto Ohta, Yi Qian

2017 39TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY (EMBC)　3385-3388　2017
Publisher: IEEE
ISSN：1094-687X

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Although flow-diversion (FD) treatment has been proven to be able to induce intracranial aneurysm (IA) occlusion, clinical follow-ups reported that a number of patients may still suffer from delayed IA rupture or incomplete aneurysm occlusion post-treatment. Complete aneurysm occlusion is believed to be associated with favourable haemodynamic alteration post-treatment, which may be greatly affected by the selection of device size and quantity, as well as the FD deployment procedure. However, clinicians have to choose and deploy the FD relying on their experience, since no post-stenting haemodynamic information is generally available to them prior to a specific treatment. In this study, using a virtual FD deployment technique and computational fluid dynamics method, we demonstrate and compare the haemodynamic changes after virtual FD treatments using a variety of prospective treating strategies.
Influence of shear stress on phenotype and MMP production of smooth muscle cells in a co-culture model Peer-reviewed

Xiaobo Han, Naoya Sakamoto, Noriko Tomita, Hui Meng, Masaaki Sato, Makoto Ohta

Journal of Biorheology　31　(2)　50-56　2017/01/01
Publisher: Japanese Society of Biorheology
DOI： 10.17106/jbr.31.50 　

ISSN：1867-0474 1867-0466

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BACKGROUND: High shear stress (SS) could affect vascular remodeling during initiation of cerebral aneurysms. However, the response of smooth muscle cells (SMCs) to high SS, which is related to blood vessel remodeling, are poorly understood. OBJECTIVE: We explored the effect of high SS on SMCs in an EC-SMC coculture model to investigate blood vessel remodeling during aneurysm formation. METHODS: SMCs were threedimensionally cultured in a collagen gel, with ECs cultured on a membrane filter above the SMCs. Then, the co-culture model was exposed to different SS of 0.2, 2, 6, and 10 Pa for 72 h. RESULTS: A physiological SS of 2 Pa maintained the expression of contractile proteins in SMCs, whereas lower or higher SS decreased the expression, suggesting a phenotypic change to a synthetic state. Furthermore, we found that a high SS of 10 Pa increased production of both matrix metalloproteinase (MMP) -2 and -9 from SMCs, which could induce destructive blood vessel remolding. CONCLUSIONS: High SS could change the SMC phenotype to a synthetic state and induce higher MMP production by SMCs in the co-culture model. These results may help to further elucidate blood vessel remodeling mechanisms under high SS conditions.
Evaluation of the effect of catheter on the guidewire motion in a blood vessel model by physical and numerical simulations Peer-reviewed

Kazuto Takashima, Atomu Oike, Kiyoshi Yoshinaka, Kaihong Yu, Makoto Ohta, Koji Mori, Naoki Toma

Journal of Biomechanical Science and Engineering　12　(4)　2017
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/jbse.17-00181 　

ISSN：1880-9863

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Various catheter simulators using a computer or blood vessel biomodels have been developed for training of medical students and young physicians. Moreover, we have developed a system to simulate a guidewire in blood vessels that uses both numerical analysis and experimental observation for the quantitative analysis of treatment technique, surgical planning, intra-operative assistance, and to facilitate the design of new guidewires. However, not limited to our group, there is a lack of studies evaluating the motions of both the guidewire and catheter and their interaction in a blood vessel. Therefore, in the present study, we modified our computer-based system and experimental apparatus to evaluate the catheter motion and compared both results. First, we added a mechanism to the experimental apparatus to move and evaluate the catheter in a poly (vinyl alcohol) hydrogel blood vessel model. Second, we added a new catheter model to the calculation. We subsequently evaluated the behaviors of the medical devices (the guidewire and the catheter) by measuring the three-dimensional position and the contact force between the medical devices and the vessel wall. Comparison of the calculation and experimental results showed that the trajectories and the contact forces of both the experimental and numerically analyzed medical devices had the same tendencies. By considering the flexibility of the catheter in both the experimental and numerical analysis methods, we could reproduce the phenomena seen in clinical situations, such as movement of the catheter during the insertion or removal of the guidewire, and movement of the guidewire during the insertion of the catheter.
Blood vessel model equipped with ultrasound sensors for evaluation of intravascular treatment Peer-reviewed

Hiroshi Yoshida, Yasutomo Shimizu, Masaaki Shojima, Makoto Ohta, Tadao Matsunaga, Noriko Tsuruoka, Yoichi Haga

Transactions of Japanese Society for Medical and Biological Engineering　55　(Proc)　544-546　2017
Publisher: Japan Soc. of Med. Electronics and Biol. Engineering
DOI： 10.11239/jsmbe.55Annual.544 　

ISSN：1347-443X 1881-4379

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Intravascular surgery, such as coil embolization and stent placement, has been widely performed for treatment of cerebral aneurysms. Doctors must be skillful and sufficiently experienced to successfully manipulate and insert a guidewire and a catheter into the aneurysm via carotid and cerebral artery. Though blood vessel model is useful for training of the doctors in the field of the intravascular surgery, evaluation of doctor’s skill and efficacy of training is insufficient. In this study, an ultrasound sensor was fabricated and equipped in the cerebral blood vessel model to measure the displacement of the vessel wall that is contacted and pushed by a guidewire or a catheter. It is confirmed that the fabricated ultrasound sensor could measure the displacement of blood vessel wall by the inserted catheter.
Ultrasound sensors installed in blood vessel model for intravascular surgery procedures. Peer-reviewed

Hiroshi Yoshida, Noriko Tsuruoka, Yasutomo Shimizu, Kaihong Yu, Makoto Ohta, Masaaki Shojima, Tadao Matsunaga, Yoichi Haga

IEEE International Conference on Cyborg and Bionic Systems, CBS 2017, Beijing, China, October 17-19, 2017　289-292　2017
Publisher: IEEE
DOI： 10.1109/CBS.2017.8266117 　
Development of a blood vessel model with ultrasound sensors to quantify intravascular treatment skills. Peer-reviewed

Hiroshi Yoshida, Tadao Matsunaga, Yasutomo Shimizu, Masaaki Shojima, Kaihong Yu, Makoto Ohta, Noriko Tsuruoka, Yoichi Haga

International Symposium on Micro-NanoMechatronics and Human Science, MHS 2017, Nagoya, Japan, December 3-6, 2017　1-4　2017
Publisher: IEEE
DOI： 10.1109/MHS.2017.8305199 　
Local internal pressure measurement system of cerebral aneurysm model using ultra-miniature fiber-optic pressure sensor. Peer-reviewed

Tadao Matsunaga, Akira Ito, Soyoka Osaki, Yasutomo Shimizu, Masaaki Shojima, Hiroshi Yoshida, Noriko Tsuruoka,Array, Makoto Ohta, Yoichi Haga

International Symposium on Micro-NanoMechatronics and Human Science, MHS 2017, Nagoya, Japan, December 3-6, 2017　1-3　2017
Publisher: IEEE
DOI： 10.1109/MHS.2017.8305197 　
Multipoint pressure measurement in blood vessel model for evaluation of intravascular treatment of cerebral aneurysm using fiber-optic pressure sensors Peer-reviewed

Matsunaga, Tadao, Haga, Yoichi, Osaki, Soyoka, Shimizu, Yasutomo, Tupin, Simon, Ohta, Makoto, Shojima, Masaaki, Yoshida, Hiroshi, Tsuruoka, Noriko, IEEE

2017 Ieee International Conference on Cyborg and Bionic Systems (Cbs)　2017
COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF THE BONE MARROW IN CANCELLOUS BONE AS A NON-NEWTONIAN FLUID Peer-reviewed

Makoto Ohta, Wataru Sakuma, Toshio Nakayama, Hitomi Anzai, Makoto Ito, Katsuyuki Sado, Shuji Nakamura

PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2016, VOL. 3　2016　2017
Publisher: AMER SOC MECHANICAL ENGINEERS

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Stem cells in the bone marrow (BM) are used as regenerative treatment for leukemia. They are usually harvested by puncturing the cancellous bone in the ilium of the donor with a needle. However, this process can cause severe burden to the donor because of its inefficiency; the bone may require 50-100 punctures to obtain enough stem cells. Various factors affect the volume of BM harvested, and their influence can be estimated by observing the flow in the cancellous bone. Recent computational fluid dynamics (CFD) analyses of BM with 3-D reconstruction of the cancellous bone have profiled flow velocity or wall shear stress (WSS) and have shown that some parts on the surface of the cancellous bone have higher WSS and that this high WSS may tear cells from the surface of the bone. CFD analysis may therefore help determining a method for efficient stem cell harvest. However, it is difficult to validate CFD using BM structure because of its porosity. To improve the accuracy of WSS and flow pattern calculations, blood characteristics should be incorporated as key factors and the effects of non-Newtonian flow and viscosity on the flow patterns evaluated. Therefore, the purpose of this study was to evaluate CFD analyses of BM in the cancellous bone based on flow where viscosity depended on the shear rate. BM from porcine ilium bones was extracted, and the viscosities of samples, with or without anti-clotting medications, were measured at various shear rates. 3-D reconstruction of the cancellous bone was performed using micro-CT after removing BM and fat from the bone. The resolution of the reconstruction was 11.7 mu m per pixel, which was sufficient to reconstruct the porous structure. The size of the bone sample was 2.5 x 2.5 x 3.5 mm. The number of mesh was approximately 4.3 million. CFD analyses were performed using 3-D reconstruction and viscosity profile at three pressure differences (5, 7, and 10 kPa). Constant pressure was applied in the outlet. The viscosity of BM could be divided into three shear rate ranges. The first corresponded with a shear rate over 100 1/s, where the viscosity was constant at less than 0.01 Pa.s. Transient curves were observed for shear rates 0.01-100 1/s. At lower shear rates, the viscosity was again constant, at over 10(5) Pa.s. These changes were higher than the changes in blood viscosity based on the shear rate. The CFD analyses showed that the results depended on the inlet pressure. When the pressure difference was 10 kPa, the viscosity change almost disappeared, and the velocity profile was similar to that of Newtonian flow. When the pressure difference was 5 or 7 kPa, changes in viscosity and completely changed flow patterns were observed. The WSS profile also changed with the velocity profile. Therefore, pressure can be a major factor in the velocity profile of BM in the cancellous bone. Effects of non-Newtonian flow on velocity and WSS profiles were observed under an appropriate pressure difference.
Deformation of stenotic blood vessel model made from Poly (Vinyl Alcohol) Hydrogel by hydrostatic pressure Peer-reviewed

Yasutomo Shimizu, Lei Liu, Hiroyuki Kosukegawa, Kenichi Funamoto, Toshiyuki Hayase, Toshio Nakayama, Makoto Ohta

PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2016, VOL. 3　2016　2017
Publisher: AMER SOC MECHANICAL ENGINEERS

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Vascular plaque deformation reduces blood flow, increases arterial embolism risk, and may lead to ischemic stroke. Plaque stiffness varies widely and is an important factor influencing both plaque and parent artery deformation. These geometric changes affect local hemodynamics, which impact plaque initiation influencing disease progression. However, most previous studies used non-elastic stenotic vessel models. For more realistic analysis, we constructed a stenosis model comprising an elastic poly (vinyl alcohol) hydrogel (PVA-H) parent artery and plaque of variable stiffness. Our previous study using this flexible model demonstrated substantial effects of hydrostatic pressure. Here ultrasonography was conducted under changing hydrostatic pressure to measure geometric changes at the narrowest cross section. PVA-H specimens were constructed with the stiffness of a hard lipid core, smooth muscle, and plaque, as estimated by tensile tests using 5, 12, and 15 wt% PVA, respectively. The change in cross-sectional aspect ratio (height/face length) at the narrowest site is largest (similar to 1.3) for the 5 wt% PVA-H plaque and smallest (similar to 1.2) for the 12 wt% PVA-H plaque. Stenotic artery deformation depends on both artery and plaque elasticity. Hydrostatic pressure has a substantial effect on both vessel and plaque geometries, which markedly alter blood flow.
DEVELOPMENT OF THE WORKING FLUID WITH BLOOD VISCOSITY FOR EVALUATING ABLATION CATHETER IN IN VITRO SYSTEM Peer-reviewed

Kaihong Yu, Ren Takahashi, Makoto Ohta

PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2016, VOL. 3　2016　2017
Publisher: AMER SOC MECHANICAL ENGINEERS

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The purpose of this study was to develop a working fluid with the proper viscosity to mimic blood flow to evaluate an ablation catheter. We proposed a working fluid that matches the blood viscosity, using glycerol-saline solution or xanthan gum (XG)saline solution. We compared the two solution mixtures at various concentrations (for glycerol-saline solution, 10%, 30%, and 50%; for XG-saline solution, 0.10%, 0.11%, 0.12%, and 0.13%) by measuring their temperature dependence on viscosity. To test the developed working fluids, RF ablations were performed with both solutions, and the flow around the catheter during ablation was observed by particle image velocimetry (PIV) method. In addition, to test the efficacy of the solution mixtures, myocardium was observed after it was soaked separately in the two solution mixtures. The viscosity of both kinds of solution mixtures increased at higher concentrations and decreased with increasing temperatures. At 37 degrees C, the viscosities of 50% glycerol-saline solution and 0.11%-0.13% XG-saline solution were 3-4 mPa.s, a value that is similar to the viscosity of blood. The upward flow resulting from heat convection by ablation was observed around the catheter in the PIV analysis using an in vitro model without flow. The solution mixture with the higher viscosity flowed at a lower velocity around the catheter, and the myocardium soaked in 50% glycerol -saline solution shrunk into a black and tough tissue. On the other hand, the myocardium soaked in XG-saline solution showed no change in color or shape. In conclusion, the XG-saline solution is a superior option for evaluating ablation catheters.
FLOW SIMULATIONS TO ESTABLISH THE RELATIONSHIP BETWEEN THE INFLOW ZONE IN THE NECK OF A CEREBRAL ANEURYSM AND THE POSITIONS OF STRUTS Peer-reviewed

Kazuhiro Watanabe, Hitomi Anzai, Makoto Ohta

PROCEEDINGS OF THE ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION, 2016, VOL. 3　2016　2017
Publisher: AMER SOC MECHANICAL ENGINEERS

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Flow-diverter (FD) stent implantation is an attractive treatment for cerebral aneurysms because of its low level of invasiveness. FD stent has a fine mesh structure, and the aim of FD implantation is to reduce the blood flow in an aneurysm by covering the aneurysm orifice. However, the fine mesh of the implant poses the risk of parent artery occlusion. One approach for avoiding this risk is to use a stent with a higher porosity. Previous studies have shown that placing a strut to disturb the inflow entering an aneurysm can promote a higher reduction in aneurysm flow. However, Hirabayashi et al. reported that a high-porosity stent can be sensitive to misdeployment in flow reduction. We hypothesized that a positioning error in flow reduction was sensitive to the relative position of the strut to the inflow configuration. In this study, we performed flow simulation to investigate the relationship between the inflow zone of the aneurysm neck and the positions of struts. Lattice Boltzmann (LB) flow simulation was performed to allow a comprehensive study of strut positions. Two rectangular solids were used as the strut model. Steady flow simulation was applied to models based on ideal and realistic three-dimensional (3D) aneurysm geometry, changing two strut positions along the neck plane. For both models, velocity boundaries were imposed on the inlet and a constant pressure boundary was imposed on the outlet. Average flow velocity in an aneurysm was calculated to evaluate the dependency of the flow reduction effect on the deployment position. We analyzed aneurysm flow using the following three strategies to observe the relationship between flow configuration, strut configuration, and flow reduction. Analysis A: Flow reduction rate (R-f) with one strut. A strut was moved from the proximal to the distal neck (perpendicular deployment) or from outside to inside (parallel deployment). Analysis B: R-f with two struts. One strut (strut A) was fixed in a specific position on the neck plane. The other (strut B) was moved along the neck plane in parallel to strut A. Analysis C: R-f with two struts. Strut B was located on the distal or inner side of strut A. The distance between the two struts was changed, and the two struts were moved along the neck plane while maintaining that distance. From the results of Analyses A and B, we confirmed a critical area in the inflow zone that maintained a high flow reduction regardless of the position of the second strut. The results of Analysis C confirmed that there were several distances between the struts at which flow reduction was almost constant. This constant reduction was maintained when one of the struts was located in the critical area, whereas the reduction was disturbed if both struts were located outside the area. These results suggest that the influence of positioning errors can be reduced by constantly placing at least one strut in a critical area, resulting in a high flow reduction. This may lead to optimal stent porosity for flow reduction and robustness of deployment.
FLOW SIMULATIONS TO ESTABLISH THE RELATIONSHIP BETWEEN THE INFLOW ZONE IN THE NECK OF A CEREBRAL ANEURYSM AND THE POSITIONS OF STRUTS Peer-reviewed

Watanabe, Kazuhiro, Anzai, Hitomi, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2016, Vol. 3　2017
DEVELOPMENT OF THE WORKING FLUID WITH BLOOD VISCOSITY FOR EVALUATING ABLATION CATHETER IN IN VITRO SYSTEM Peer-reviewed

Yu, Kaihong, Takahashi, Ren, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2016, Vol. 3　2017
Development of a poly (vinyl alcohol) hydrogel phantom to allow physical measurement in ultrasonographic conditions: a model for scatter Peer-reviewed

Takahashi, Ren, Tamura, Kazuki, Yamaguchi, Tadashi, Shimizu, Yasutomo, Ohta, Makoto, IEEE

2017 Ieee International Conference on Cyborg and Bionic Systems (Cbs)　150-153　2017

DOI： 10.1109/CBS.2017.8266087 　
Deformation of stenotic blood vessel model made from Poly (Vinyl Alcohol) Hydrogel by hydrostatic pressure Peer-reviewed

Shimizu, Yasutomo, Liu, Lei, Kosukegawa, Hiroyuki, Funamoto, Kenichi, Hayase, Toshiyuki, Nakayama, Toshio, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2016, Vol. 3　2017
COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF THE BONE MARROW IN CANCELLOUS BONE AS A NON-NEWTONIAN FLUID Peer-reviewed

Ohta, Makoto, Sakuma, Wataru, Nakayama, Toshio, Anzai, Hitomi, Ito, Makoto, Sado, Katsuyuki, Nakamura, Shuji, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2016, Vol. 3　2017
Manufacture of patient-specific vascular replicas for endovascular simulation using fast, low-cost method. International-journal Peer-reviewed

Naoki Kaneko, Toshihiro Mashiko, Taihei Ohnishi, Makoto Ohta, Katsunari Namba, Eiju Watanabe, Kensuke Kawai

Scientific reports　6　39168-39168　2016/12/15

DOI： 10.1038/srep39168 　

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Patient-specific vascular replicas are essential to the simulation of endovascular treatment or for vascular research. The inside of silicone replica is required to be smooth for manipulating interventional devices without resistance. In this report, we demonstrate the fabrication of patient-specific silicone vessels with a low-cost desktop 3D printer. We show that the surface of an acrylonitrile butadiene styrene (ABS) model printed by the 3D printer can be smoothed by a single dipping in ABS solvent in a time-dependent manner, where a short dip has less effect on the shape of the model. The vascular mold is coated with transparent silicone and then the ABS mold is dissolved after the silicone is cured. Interventional devices can pass through the inside of the smoothed silicone vessel with lower pushing force compared to the vessel without smoothing. The material cost and time required to fabricate the silicone vessel is about USD $2 and 24 h, which is much lower than the current fabrication methods. This fast and low-cost method offers the possibility of testing strategies before attempting particularly difficult cases, while improving the training of endovascular therapy, enabling the trialing of new devices, and broadening the scope of vascular research.
Surgical resection of recurrent extrahepatic hepatocellular carcinoma with tumor thrombus extending into the right atrium under cardiopulmonary bypass: a case report and review of the literature. International-journal Peer-reviewed

Ohta M, Nakanishi C, Kawagishi N, Hara Y, Maida K, Kashiwadate T, Miyazawa K, Yoshida S, Miyagi S, Hayatsu Y, Kawamoto S, Matsuda Y, Okada Y, Saiki Y, Ohuchi N

Surgical case reports　2　(1)　110-110　2016/12

DOI： 10.1186/s40792-016-0241-7 　

ISSN：2198-7793

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BACKGROUND: Recurrent hepatocellular carcinoma accompanied by a right atrial tumor thrombus is rare. No standard treatment modality has been established. Surgical treatment may be the only curative treatment; however, surgery has been considered high risk. We herein describe a patient who underwent resection of a recurrent right atrial tumor thrombus under normothermic cardiopulmonary bypass on a beating heart. CASE PRESENTATION: A 60-year-old man underwent a right hepatectomy for hepatocellular carcinoma with diaphragm invasion. During the preoperative cardiac screening, he was diagnosed with an old myocardial infarction with triple-vessel coronary disease. Percutaneous coronary intervention was performed for the left anterior descending artery and left circumflex coronary artery. High-grade stenosis remained in his right coronary artery. Nine months later, computed tomography showed recurrent hepatocellular carcinoma in the diaphragm and a tumor thrombus extending from the suprahepatic inferior vena cava into the right atrium. Surgical resection of the recurrent tumor was performed through a right subcostal incision with xiphoid extension and median sternotomy. The recurrent tumor was incised with the diaphragm and pericardium. Intraoperative ultrasonography revealed that the tumor thrombus was free from right atrium wall invasion and that the right atrium could be clamped just proximal to the tumor thrombus. The right atrium, infrahepatic vena cava, left and middle hepatic veins, and hepatoduodenal ligament were encircled. Cardiopulmonary bypass was performed to prevent ischemic heart disease caused by intraoperative hypotension. Total hepatic vascular exclusion was then performed under normothermic cardiopulmonary bypass on heart beating. The inferior vena cava wall was incised. The tumor thrombus with the diaphragmatic recurrent tumor was resected en bloc. The patient had a favorable clinical course without any complications. CONCLUSION: The recurrent hepatocellular carcinoma in the diaphragm and the right atrial tumor thrombus were safely resected using normothermic cardiopulmonary bypass on heart beating.
Daughter Sac Formation Related to Blood Inflow Jet in an Intracranial Aneurysm. International-journal Peer-reviewed

Sin-Ichiro Sugiyama, Hidenori Endo, Shunsuke Omodaka, Toshiki Endo, Kuniyasu Niizuma, Sherif Rashad, Toshio Nakayama, Kenichi Funamoto, Makoto Ohta, Teiji Tominaga

World neurosurgery　96　396-402　2016/12

DOI： 10.1016/j.wneu.2016.09.040 　

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OBJECTIVE: We performed a hemodynamic study of an intracranial aneurysm with a newly developed daughter sac during observation to investigate the role of hemodynamics on the formation of a daughter sac. METHODS: A 75-year-old man underwent magnetic resonance angiography that revealed a large internal carotid artery aneurysm with inflow jet inside the aneurysm. The aneurysm was stable for 18 months, but a new daughter sac developed at the tip of the aneurysm during the next 6 months. The daughter sac seemed to be related to the inflow jet on magnetic resonance angiography. Aneurysm geometries before and after daughter sac formation were reconstructed using the longitudinal data of magnetic resonance angiography. Computational fluid dynamic simulations were conducted under the patient-specific pulsatile inlet conditions measured by magnetic resonance velocimetry. RESULTS: The hemodynamic simulation revealed that the inflow jet impinged on 2 sites of the aneurysm: the right side of the aneurysmal dome and the tip of the aneurysm. The flow impingement caused elevation of pressure at both sites. However, the daughter sac formed at the latter site surrounded by the basal cistern but did not form at the former site that was in contact with the right temporal lobe. CONCLUSIONS: Blood inflow jet caused local elevation of pressure, and the formation of the daughter sac occurred at the site with high pressure but without the surrounding structure, which may cancel the perpendicular wall tension.
Towards the patient-specific design of flow diverters made from helix-like wires: an optimization study International-journal Peer-reviewed

Mingzi Zhang, Hitomi Anzai, Bastien Chopard, Makoto Ohta

BIOMEDICAL ENGINEERING ONLINE　15　(Suppl 2)　159-159　2016/12
Publisher: BIOMED CENTRAL LTD
DOI： 10.1186/s12938-016-0257-z 　

ISSN：1475-925X

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Background: Flow diverter (FD) intervention is an emerging endovascular technique for treating intracranial aneurysms. High flow-diversion efficiency is desired to accelerate thrombotic occlusion inside the aneurysm; however, the risk of post-stenting stenosis in the parent artery is posed when flow-diversion efficiency is pursued by simply decreasing device porosity. For improving the prognosis of FD intervention, we develop an optimization method for the design of patient-specific FD devices that maintain high levels of porosity.Methods: An automated structure optimization method for FDs with helix-like wires was developed by applying a combination of lattice Boltzmann fluid simulation and simulated annealing procedure. Employing intra-aneurysmal average velocity as the objective function, the proposed method tailored the wire structure of an FD to a given vascular geometry by rearranging the starting phase of the helix wires.Results: FD optimization was applied to two idealized (S and C) vascular models and one realistic (R) model. Without altering the original device porosity of 80%, the flow-reduction rates of optimized FDs were improved by 5, 2, and 28% for the S, C, and R models, respectively. Furthermore, the aneurysmal flow patterns after optimization exhibited marked alterations. We confirmed that the disruption of bundle of inflow is of great help in blocking aneurysmal inflow. Axial displacement tests suggested that the optimal FD implanted in the R model possesses good robustness to tolerate uncertain axial positioning errors.Conclusions: The optimization method developed in this study can be used to identify the FD wire structure with the optimal flow-diversion efficiency. For a given vascular geometry, custom-designed FD structure can maximally reduce the aneurysmal inflow with its porosity maintained at a high level, thereby lowering the risk of post-stenting stenosis. This method facilitates the study of patient-specific designs for FD devices.
Blood Flow Into Basilar Tip Aneurysms: A Predictor for Recanalization After Coil Embolization. International-journal Peer-reviewed

Shin-Ichiro Sugiyama, Kuniyasu Niizuma, Kenichi Sato, Sherif Rashad, Misaki Kohama, Hidenori Endo, Toshiki Endo, Yasushi Matsumoto, Makoto Ohta, Teiji Tominaga

Stroke　47　(10)　2541-7　2016/10

DOI： 10.1161/STROKEAHA.116.013555 　

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BACKGROUND AND PURPOSE: Hemodynamic forces may play a role in the recanalization of coiled aneurysms. The purpose of this study was to investigate the influence of presurgical hemodynamics on the efficacy of coil embolization for basilar tip aneurysms. METHODS: We identified 82 patients who underwent endovascular coil embolization for basilar tip aneurysms with a follow-up of >1 year. Presurgical hemodynamics were investigated using computational fluid dynamics with 3-dimensional data derived from rotational angiography. During postprocessing, we quantified the rate of net flow entering the aneurysm through its neck and calculated the proportion of the aneurysmal inflow rate to the basilar artery flow rate. In addition, we investigated the correlation between the basilar bifurcation configuration and the hemodynamics. RESULTS: Twenty-five of the 82 patients were excluded because of difficult vascular geometry reconstruction. Among the 57 examined patients, angiographic recanalization was observed in 19 patients (33.3%). The proportion of the aneurysmal inflow rate to the basilar artery flow rate and a coil packing density <30% were independent and significant predictors for the recanalization of coiled aneurysms. Additional investigation revealed that a small branch angle formed by the basilar artery and the posterior cerebral artery increased blood flow into the aneurysm. CONCLUSIONS: The proportion of the aneurysmal inflow rate to the basilar artery flow rate, influenced by the basilar bifurcation configuration, was an independent and significant predictor for recanalization after coil embolization in basilar tip aneurysms.
医工学分野におけるCAVE活用

安西眸, 渡邉和浩, 張明子, Narendra Kurnia Putra, 竹島由里子, 太田信

可視化情報　36　(143)　20-24　2016/10

ISSN：0916-4731
The Transmembrane Domain of a Bicomponent ABC Transporter Exhibits Channel-Forming Activity. International-journal Peer-reviewed

Mohammad M Mohammad, Noriko Tomita, Makoto Ohta, Liviu Movileanu

ACS chemical biology　11　(9)　2506-18　2016/09/16

DOI： 10.1021/acschembio.6b00383 　

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Pseudomonas aeruginosa is an opportunistic pathogen that expresses two unique forms of lipopolysaccharides (LPSs) on its bacterial surface, the A- and B-bands. The A-band polysaccharides (A-band PSs) are thought to be exported into the periplasm via a bicomponent ATP-binding cassette (ABC) transporter located within the inner membrane. This ABC protein complex consists of the transmembrane (TMD) Wzm and nucleotide-binding (NBD) Wzt domain proteins. Here, we were able to probe ∼1.36 nS-average conductance openings of the Wzm-based protein complex when reconstituted into a lipid membrane buffered by a 200 mM KCl solution, demonstrating the large-conductance, channel-forming ability of the TMDs. In agreement with this finding, transmission electron microscopy (TEM) imaging revealed the ring-shaped structure of the transmembrane Wzm protein complex. As hypothesized, using liposomes, we demonstrated that Wzm interacts with Wzt. Further, the Wzt polypeptide indeed hydrolyzed ATP but exhibited a ∼75% reduction in the ATPase activity when its Walker A domain was deleted. The distribution and average unitary conductance of the TMD Wzm protein complex were altered by the presence of the NBD Wzt protein, confirming the regulatory role of the latter polypeptide. To our knowledge, the large-conductance, channel-like activity of the Wzm protein complex, although often hypothesized, has not previously been demonstrated. These results constitute a platform for future structural, biophysical, and functional explorations of this bicomponent ABC transporter.
Suppression of Wall Shear Stress inside Intracranial Aneurysms by Simple Stents Peer-reviewed

Ryuhei yamaguchi, Hitomi Anzai, Gaku Tanaka, Hao Liu, Makoto Ohta

Neuroscience Communications　2　2016/09
Tribological aspects of drilling bone biomodel Peer-reviewed

Y. Muramoto, V. Fridrici, Ph. Kapsa, G. Bouvard, M. Ohta

Procédés et Génie civil(Journées Internationals Francophones de Tribologie )　JIFT2015　81-89　2016/09
Effect of elasticity on wall shear stress inside cerebral aneurysm at anterior cerebral artery. International-journal Peer-reviewed

Lijian Xu, Michiko Sugawara, Gaku Tanaka, Makoto Ohta, Hao Liu, Ryuhei Yamaguchi

Technology and health care : official journal of the European Society for Engineering and Medicine　24　(3)　349-57　2016/05/18

DOI： 10.3233/THC-161135 　

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BACKGROUND: Many numerical studies have been published with respect to about flow structures around cerebral aneurysm assuming to be rigid. Furthermore, there is little experimental research concerning aneurysm with elastic wall. Wall shear stress in elastic wall comparing with rigid wall should be clarified in experimental approach and verified in CFD. OBJECTIVE: We have experimentally realized elastic aneurysm model accompanying with wall deformation. Wall shear stress was examined for both rigid and elastic aneurysm models in pulsatile flow. METHODS: Effect of elasticity on wall shear stress inside aneurysm induced at the apex of anterior cerebral artery was experimentally examined by particle image velocimetry in vitro. In order to adjust the wall deformation, the pressure adjustment chamber was specially equipped outside the aneurysm wall. RESULTS: Effect of elasticity on wall shear stress was noticed on the comparison with that of rigidity. Wall elasticity reduced the peak magnitude, the spatial and temporal averaged wall shear stress comparing with those of wall rigidity experimentally. These reductions were endorsed by fluid-structure interaction simulation. CONCLUSION: Elastic wall comparing with rigid wall would reduce the peak magnitude, the spatial and temporal averaged wall shear stress acting on vascular wall.
Radiofrequency ablation with a vibrating catheter: A new method for electrode cooling. International-journal Peer-reviewed

Kaihong Yu, Tetsui Yamashita, Shigeaki Shingyochi, Kazuo Matsumoto, Makoto Ohta

Medical engineering & physics　38　(5)　458-67　2016/05

DOI： 10.1016/j.medengphy.2016.02.011 　

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A new electrode cooling system using a vibrating catheter is described for conditions of low blood flow when saline irrigation cannot be used. Vibrations of the catheter are hypothesized to disturb blood flow around the electrode, leading to increased convective cooling of the electrode. The aim of this study is to confirm the cooling effect of vibration and investigate the associated mechanisms. As methods, an in vitro system with polyvinyl alcohol-hydrogel (PVA-H) as ablated tissue and saline flow in an open channel was used to measure changes in electrode and tissue temperatures under vibration of 0-63 Hz and flow velocity of 0-0.1 m/s. Flow around the catheter was observed using particle image velocimetry (PIV). Results show that under conditions of no flow, electrode temperatures decreased with increasing vibration frequency, and in the absence of vibrations, electrode temperatures decreased with increasing flow velocity. In the presence of vibrations, electrode temperatures decreased under conditions of low flow velocity, but not under those of high flow velocity. PIV analyses showed disturbed flow around the vibrating catheter, and flow velocity around the catheter increased with higher-frequency vibrations. In conclusion, catheter vibration facilitated electrode cooling by increasing flow around the catheter, and cooling was proportional to vibration frequency.
Difference in Transcranial Doppler Velocity and Patient Age between Proximal and Distal Middle Cerebral Artery Vasospasms after Aneurysmal Subarachnoid Hemorrhage. International-journal Peer-reviewed

Misaki Kohama, Shinichiro Sugiyama, Kenichi Sato, Hidenori Endo, Kuniyasu Niizuma, Toshiki Endo, Makoto Ohta, Yasushi Matsumoto, Miki Fujimura, Teiji Tominaga

Cerebrovascular diseases extra　6　(2)　32-9　2016

DOI： 10.1159/000447330 　

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BACKGROUND: Transcranial Doppler (TCD) is used to monitor cerebral vasospasm after subarachnoid hemorrhage (SAH), but its diagnostic ability is reported to be limited. Therefore, the purpose of this study was to investigate the relationship between the diagnosability of TCD and the localization of the vasospasm. METHODS: This retrospective study included 20 patients who presented with symptomatic vasospasm after SAH. All 20 patients underwent daily TCD examinations and cerebral angiography after the onset of delayed cerebral ischemia. We defined positive findings on TCD as a maximum flow velocity >200 cm/s or as a mean flow velocity >120 cm/s at the horizontal part of the middle cerebral artery (MCA). We also examined the site of vasospasm on cerebral angiography. RESULTS: Fourteen patients had true-positive findings on TCD examination, and cerebral angiography showed diffuse vasospasm involving the horizontal segment of the MCA. However, 6 patients had false-negative findings on TCD examination, and cerebral angiography showed vasospasm localized at the distal part of the MCA (the insular and/or cortical segments). The patients with proximal vasospasm were significantly younger than those with distal vasospasm. Blood flow velocity at initial TCD and the increase in velocity at the onset of vasospasm were lower and smaller, respectively, in the distal vasospasm group. CONCLUSIONS: In patients with cerebral vasospasm localized at the distal part of the MCA, flow velocity at the horizontal segment of the MCA did not increase to the level we defined as positive. To avoid such false negatives, a slight increase in velocity on TCD should be considered as positive in distal vasospasm cases, especially in older patients.
Computational Hemodynamic Analysis for the Diagnosis of Atherosclerotic Changes in Intracranial Aneurysms: A Proof-of-Concept Study Using 3 Cases Harboring Atherosclerotic and Nonatherosclerotic Aneurysms Simultaneously. International-journal Peer-reviewed

Shin-Ichiro Sugiyama, Hidenori Endo, Kuniyasu Niizuma, Toshiki Endo, Kenichi Funamoto, Makoto Ohta, Teiji Tominaga

Computational and mathematical methods in medicine　2016　2386031-2386031　2016

DOI： 10.1155/2016/2386031 　

eISSN：1748-6718

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This was a proof-of-concept computational fluid dynamics (CFD) study designed to identify atherosclerotic changes in intracranial aneurysms. We selected 3 patients with multiple unruptured aneurysms including at least one with atherosclerotic changes and investigated whether an image-based CFD study could provide useful information for discriminating the atherosclerotic aneurysms. Patient-specific geometries were constructed from three-dimensional data obtained using rotational angiography. Transient simulations were conducted under patient-specific inlet flow rates measured by phase-contrast magnetic resonance velocimetry. In the postanalyses, we calculated time-averaged wall shear stress (WSS), oscillatory shear index, and relative residence time (RRT). The volume of blood flow entering aneurysms through the neck and the mean velocity of blood flow inside aneurysms were examined. We applied the age-of-fluid method to quantitatively assess the residence of blood inside aneurysms. Atherosclerotic changes coincided with regions exposed to disturbed blood flow, as indicated by low WSS and long RRT. Blood entered aneurysms in phase with inlet flow rates. The mean velocities of blood inside atherosclerotic aneurysms were lower than those inside nonatherosclerotic aneurysms. Blood in atherosclerotic aneurysms was older than that in nonatherosclerotic aneurysms, especially near the wall. This proof-of-concept study demonstrated that CFD analysis provided detailed information on the exchange and residence of blood that is useful for the diagnosis of atherosclerotic changes in intracranial aneurysms.
Manufacture-Oriented Design Optimization for a Flow Diverter Stent Using Lattice Boltzmann Method and Simulated Annealing International-coauthorship Peer-reviewed

Mingzi Zhang, Hitomi Anzai, Bastien Chopard, Makoto Ohta

Advances in Structural and Multidisciplinary Optimization - Proceedings of the 11th World Congress of Structural and Multidisciplinary Optimization (WCSMO-11)　11　310-315　2015/06
Comparison of intra-aneurysmal velocity magnitude in a patient-specific model among PIV, CFD and MRI

Yujie Li, Yoneyama Yuuya, Haruo Isada, Takahumi Kosugi, Takashi Kosugi, Makoto Ohta

2015 ELyT lab Workshop　2015/02/20
Flow in cancellous bone

Wataru Sakuma, Hitomi Anzai, Toshio Nakayama, Makoto Ohta

2015 ELyT lab Workshop　2015/02/20
Optimization of endovascular prosthesis for the treatment ofcerebral aneurysms

Hitomi Anzai, Makoto Ohta, Guy courbebaisse, Mingzi Zhang, Bastien Chopard, Yue zhang

2015 ELyT lab Workshop　2015/02/20
The Effect of Vibration Ablation Catheter on the Temperature of the Electrode under 30 gf

Kaihong Yu, Vincent Fridrici, Philippe Kapsa, Makoto Ohta

2015 ELyT lab Workshop　2015/02/20
Introduction of Three Strut Optimization Strategies towards the Design of Efficient Flow-Diverter Stents

Mingzi Zhang, Hitomi Anzai, Makoto Ohta

2015 ELyT lab Workshop　2015/02
Preface for the "Special issue on biomedical flow dynamics" Peer-reviewed

Toshiyuki Hayase, Takehiko Sato, Makoto Ohta

Journal of Biomechanical Science and Engineering　10　(1)　1-1　2015
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/jbse.15preface01 　

ISSN：1880-9863
Parametric study of porous media as substitutes for flow-diverter stent Peer-reviewed

Ohta, Makoto, Anzai, Hitomi, Miura, Yukihisa, Nakayama, Toshio

Biomaterials and Biomechanics in Bioengineering　2　(2)　2015

DOI： 10.12989/bme.2015.2.2.111 　
Accuracy and Reproducibility of Patient-Specific Hemodynamic Models of Stented Intracranial Aneurysms: Report on the Virtual Intracranial Stenting Challenge 2011 Peer-reviewed

Cito, S., Geers, A. J., Arroyo, M. P., Palero, V. R., Pallares, J., Vernet, A., Blasco, J., San Roman, L., Fu, W., Qiao, A., Janiga, G., Miura, Y., Ohta, M., Mendina, M., Usera, G., Frangi, A. F.

Annals of Biomedical Engineering　43　(1)　154-167　2015

DOI： 10.1007/s10439-014-1082-9 　
Friction of 316L stainless steel on soft-tissue-like poly(vinyl alcohol) hydrogel in physiological liquid Peer-reviewed

Kosukegawa, Hiroyuki, Fridrici, Vincent, Laurenceau, Emmanuelle, Kapsa, Philippe, Ohta, Makoto

Tribology International　82　(PB)　407-414　2015

DOI： 10.1016/j.triboint.2014.05.029 　
Changes in blood flow due to stented parent artery expansion in an intracranial aneurysm Peer-reviewed

Futoshi Moria, Makoto Ohta, Teruo Matsuzawa

TECHNOLOGY AND HEALTH CARE　23　(1)　9-21　2015
Publisher: IOS PRESS
DOI： 10.3233/THC-140871 　

ISSN：0928-7329

eISSN：1878-7401

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BACKGROUND: Stent placement is thought to obstruct the inflow of blood to an aneurysm. However, we introduced parent artery expansion and demonstrated that this may reduce the blood flow by the stent. In our previous study using idealized shapes, the results showed that flow reduction was greater than 22.2%, even if the expansion rate was only 6%. Furthermore, the parent artery expansion is predominantly caused by the effect of flow reduction as compared to that of flow reduction due to the obstruction of flow under stent placement. However, a realistic shape is complex and the blood flow also becomes complex flow. It is not understood whether the results of flow in the idealized shape are reflective of flow from a realistic 3D model. Therefore, we examined the effect of parent artery expansion using a realistic model. OBJECTIVE: The aim is to clarify the effects of parent artery expansion on inflow rate, wall shear stress, and oscillatory shear index. METHODS: We used a patient-specific geometry of a human internal carotid artery with an aneurysm. The geometry of parent artery expansion due to oversized stent constructed based on the voronoi diagram. We performed calculations in the unsteady-state situations using constructed models. RESULTS: The complexity of the flow in the aneurysm decreases in case of expanded parent artery. The inflow rate decreases by 33.6% immediately after parent artery expansion alone without a stent. The effect of the parent artery expansion on flow reduction is larger than that of the obstruction flow by stent placement. In addition, wall shear stress and oscillatory shear index on the aneurysm wall decrease by change in blood flow due to the parent artery expansion. CONCLUSION: The effects of the parent artery expansion in a realistic aneurysm model with different stent lengths were evaluated on the basis of a numerical simulation. Although the flow was complex, the parent artery expansion with stent reduces the inflow to the aneurysm and wall shear stress and oscillatory shear index on the aneurysm. Therefore, we suggest that changes in the blood flow because of the parent artery expansion may be identified and, sometimes, is more effective than the obstruction flow due to the stent placement.
Comparative analysis for evaluating the traceability of interventional devices using blood vessel phantom models made of PVA-H or silicone. International-journal Peer-reviewed

Chang-Ho Yu, Tae-Kyu Kwon, Chan Hee Park, Makoto Ohta, Sung Hoon Kim

Technology and health care : official journal of the European Society for Engineering and Medicine　23 Suppl 2　(s2)　S301-10-310　2015

DOI： 10.3233/THC-150966 　

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OBJECTIVE: In this paper, we investigated the parameters with effective traceability to assess the mechanical properties of interventional devices. METHODS: In our evaluation system, a box-shaped poly (vinyl alcohol) hydrogel (PVA-H) and silicone were prepared with realistic geometry, and the measurement and evaluation of traceability were carried out on devices using load hand force. The phantom models had a total of five curve pathways to reach the aneurysm sac. RESULTS: Traceability depends on the performance of the interventional devices in order to pass through the curved part of the model simulation track. The traceability of the guide wire was found to be much better than that of the balloon and stent loading catheter, as it reached the aneurysm sac in both phantom models. CONCLUSIONS: Observation using the video record is another advantage of our system, because the high transparency of the materials with silicone and PVA-H can allow visualization of the inside of an artery.
Influence of plaque stiffness on deformation and blood flow patterns in models of stenosis. International-journal Peer-reviewed

Yasutomo Shimizu, Makoto Ohta

Biorheology　52　(3)　171-82　2015

DOI： 10.3233/BIR-14016 　

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BACKGROUND: Blood flow in stenotic vessels strongly influences the progression of vascular diseases. Plaques in stenotic blood vessels vary in stiffness, which influences plaque behavior and deformation by pressure and flow. Concurrent changes in plaque geometry can, in turn, affect blood flow conditions. Thus, simultaneous studies of blood flow and plaque deformation are needed to fully understand these interactions. OBJECTIVES: This study aims to identify the change of flow conditions attendant to plaque deformation in a model stenotic vessel. METHODS: Three plaques of differing stiffness were constructed on a vessel wall using poly (vinyl alcohol) hydrogels (PVA-H) with defined stiffness to facilitate simultaneous observations of blood flow and plaque deformation. Flow patterns were observed using particle image velocimetry (PIV). RESULTS: Decreases in Reynolds number (Re) with increased plaque deformation suggest that velocity decrease is more critical to establishment of the flow pattern than expansion of the model lumen. Upon exiting the stenosis, the location of the flow reattachment point, shifted further downstream in all models as plaque stiffness decreased and depended on the increase in upstream pressure. CONCLUSIONS: These results suggest that in addition to luminal area, plaque stiffness should be considered as a measure of the severity of the pathology.
Porosity dependency of an optimized stent design for an intracranial aneurysm Peer-reviewed

Anzai, H., Yoshida, Y., Sugiyama, S., Endo, H., Matsumoto, Y., Ohta, M.

Technology and Health Care　23　(5)　547-556　2015

DOI： 10.3233/THC-151007 　
Changes in blood flow due to stented parent artery expansion in an intracranial aneurysm. International-journal Peer-reviewed

Futoshi Mori, Makoto Ohta, Teruo Matsuzawa

Technology and health care : official journal of the European Society for Engineering and Medicine　23　(1)　9-21　2015

DOI： 10.3233/THC-140871 　

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BACKGROUND: Stent placement is thought to obstruct the inflow of blood to an aneurysm. However, we introduced parent artery expansion and demonstrated that this may reduce the blood flow by the stent. In our previous study using idealized shapes, the results showed that flow reduction was greater than 22.2%, even if the expansion rate was only 6%. Furthermore, the parent artery expansion is predominantly caused by the effect of flow reduction as compared to that of flow reduction due to the obstruction of flow under stent placement. However, a realistic shape is complex and the blood flow also becomes complex flow. It is not understood whether the results of flow in the idealized shape are reflective of flow from a realistic 3D model. Therefore, we examined the effect of parent artery expansion using a realistic model. OBJECTIVE: The aim is to clarify the effects of parent artery expansion on inflow rate, wall shear stress, and oscillatory shear index. METHODS: We used a patient-specific geometry of a human internal carotid artery with an aneurysm. The geometry of parent artery expansion due to oversized stent constructed based on the voronoi diagram. We performed calculations in the unsteady-state situations using constructed models. RESULTS: The complexity of the flow in the aneurysm decreases in case of expanded parent artery. The inflow rate decreases by 33.6% immediately after parent artery expansion alone without a stent. The effect of the parent artery expansion on flow reduction is larger than that of the obstruction flow by stent placement. In addition, wall shear stress and oscillatory shear index on the aneurysm wall decrease by change in blood flow due to the parent artery expansion. CONCLUSION: The effects of the parent artery expansion in a realistic aneurysm model with different stent lengths were evaluated on the basis of a numerical simulation. Although the flow was complex, the parent artery expansion with stent reduces the inflow to the aneurysm and wall shear stress and oscillatory shear index on the aneurysm. Therefore, we suggest that changes in the blood flow because of the parent artery expansion may be identified and, sometimes, is more effective than the obstruction flow due to the stent placement.
Numerical analysis and experimental observation of guidewire motion in a blood vessel model. International-journal Peer-reviewed

Kazuto Takashima, Shotaro Tsuzuki, Atomu Ooike, Kiyoshi Yoshinaka, Kaihong Yu, Makoto Ohta, Koji Mori

Medical engineering & physics　36　(12)　1672-83　2014/12

DOI： 10.1016/j.medengphy.2014.09.012 　

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We have developed a computer-based system to simulate a guidewire in blood vessels for surgical planning, intra-operative assistance, and to facilitate the design of new guidewires. In this study, we compared simulation results with experimental results for validation of the simulation system. First, we inserted a commercial guidewire into a poly (vinyl alcohol) hydrogel blood vessel model using a two-axis automatic stage and measured the position of the guidewire tip and the contact force between the guidewire and the vessel. The experimental apparatus can be used not only for the validation of numerical analyses, but also as a simulation system. Second, similarly to the experiment, the motion of the guidewire in the blood vessel model was calculated when the proximal part of the guidewire model was pushed and twisted. The model of the guidewire is constructed with viscoelastic springs and segments, and the proximal part of the guidewire model is constrained by the fixed catheter model. Collisions between the guidewire and the vessel are calculated, and the contact forces are determined according to the stiffness of the vessel wall. The same tendency was seen in the trajectories and the contact force of both the experimental and simulated guidewire tips.
Automation of design optimization for intracranial stent

Hitomi Anzai, Yuuki Yoshida, Mingzi Zhang, Makoto Ohta

1st International symposium for collaborative research between Tohoku University and Technische Universität Braunschweig　2014/11/11
Introduction of invitro and insilico analyses for medical equipment

Makoto Ohta

1st International symposium for collaborative research between Tohoku University and Technische Universität Braunschweig　2014/11/11
Numerical Simulation and Experimental Study of Flow Pattern in Cerebral Artery with Aneurysm

Yujie Li

Presentation at Linné FLOW Centre & Wallenberg Wood Science Center　2014/10/02
The Effect of Contact Force on Electrode Temperature and Internal Tissue Temperature during Ablation with a Vibrating Catheter

Kaihong Yu, Tetsui Yamashita, Shigeaki Shingyochi, Makoto Ohta

11th International Conference on Flow Dynamics (ICFD2014)　2014/10
An Optimization Method of FD Stent for Cerebral Aneurysm facing tne Stent Design and Manufacturing Needs

Mingzi Zhang, Hitomi Anzai, Bastien Chopard, Makoto Ohta

The Fourth Japan-Switzerland Workshop on Biomechamics (JSB2014)　14　(204)　64　2014/09/03
Development of Image Guided Minimal Invasive Treatments

Makoto Ohta, Sho Matsumoto, Xiaobo Han, Mingzi Zhang, Yujie Li, Kaihong Yu, Hitomi Anzai

The Fourth Japan-Switzerland Workshop on Biomechamics (JSB2014)　14　(204)　100-100　2014/09/03
Optimization of stent design for intracranial aneurysm

Hitomi Anzai, Yuuki Yoshida, Makoto Ohta

The Fourth Japan-Switzerland Workshop on Biomechamics (JSB2014)　14　(204)　62-62　2014/09/03
Effect of parent artery expansion by stent placement in cerebral aneurysms. International-journal Peer-reviewed

Futoshi Mori, Sho Hanida, Makoto Ohta, Teruo Matsuzawa

Technology and health care : official journal of the European Society for Engineering and Medicine　22　(2)　9-21　2014/08/05

DOI： 10.3233/THC-140829 　

eISSN：1878-7401

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BACKGROUND: Stent placement for cerebral aneurysms leads to a decrease in blood flow. This occurs not only through the direct obstruction of flow but also by the expansion of the parent artery. The latter has been observed in several clinical studies. OBJECTIVE: The goal of this study was to clarify the effects of parent artery expansion after stent treatment on the following: 1) decrease in blood flow to an aneurysm, 2) wall shear stress (WSS), and 3) oscillatory shear index (OSI). METHODS: The parent artery geometry constructed U-shape. The aneurysm location with respect to the U-shaped parent artery was determined according to previous clinical data. We performed calculations in unsteady-state situations using constructed models. RESULTS: Parent artery expansion with stent reduces blood inflow to an aneurysm and WSS of the aneurysm wall, in addition to increasing OSI. The aneurysm position affects the decrease of the inflow rate and WSS ratio and increases the OSI ratio. Expansion causes the majority of effects on flow reduction inside an aneurysm model. Thus, the expansion effects of all samples should not be neglected. CONCLUSION: These data suggest that parent artery expansion and its effect should be measured and included in the total decrease in blood flow. Parent artery expansion may induce intimal hyperplasia, thus increasing the thickness of the aneurysm wall.
Manufacture-oriented Struts Structure Optimization of Flow Diverter for Intracranial Aneurysm Peer-reviewed

Mingzi Zhang, Hitomi Anzai, Makoto Ohta

7th World Congress of Biomechanics (WCB2014)　2014/07/10
The concept of Bundle of Inflow (BOI) for reducing flow in aneurysm

Makoto Ohta, Hitomi Anzai, Mingzi Zhang, Yujie Li, Xiaobo Han, Kaihong Yu, Toshio Nakayama

7th World Congress of Biomechanics (WCB2014)　2014/07/10
Analysys of optimized design of stent

H. Anzai

Interdisciplinary Cerebrovascular Symposium　2014/06/03
Optimization of strut placement in flow diverter stents for four different aneurysm configurations. International-journal Peer-reviewed

Hitomi Anzai, Jean-Luc Falcone, Bastien Chopard, Toshiyuki Hayase, Makoto Ohta

Journal of biomechanical engineering　136　(6)　061006-061006　2014/06

DOI： 10.1115/1.4027411 　

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A modern technique for the treatment of cerebral aneurysms involves insertion of a flow diverter stent. Flow stagnation, produced by the fine mesh structure of the diverter, is thought to promote blood clotting in an aneurysm. However, apart from its effect on flow reduction, the insertion of the metal device poses the risk of occlusion of a parent artery. One strategy for avoiding the risk of arterial occlusion is the use of a device with a higher porosity. To aid the development of optimal stents in the view point of flow reduction maintaining a high porosity, we used lattice Boltzmann flow simulations and simulated annealing optimization to investigate the optimal placement of stent struts. We constructed four idealized aneurysm geometries that resulted in four different inflow characteristics and employed a stent model with 36 unconnected struts corresponding to the porosity of 80%. Assuming intracranial flow, steady flow simulation with Reynolds number of 200 was applied for each aneurysm. Optimization of strut position was performed to minimize the average velocity in an aneurysm while maintaining the porosity. As the results of optimization, we obtained nonuniformed structure as optimized stent for each aneurysm geometry. And all optimized stents were characterized by denser struts in the inflow area. The variety of inflow patterns that resulted from differing aneurysm geometries led to unique strut placements for each aneurysm type.
ステントの最適デザインを考える Invited

太田信, 安西眸, 吉田裕貴, Mingzi Zhang, Yujie Li, 中山敏男

脳神経外科速報　24　(5)　532-537　2014/05
Combinational optimization of strut placement for intracranial stent using a realistic aneurysm Peer-reviewed

Hitomi Anzai, Bastien Chopard, Makoto Ohta

Journal of Flow Control,Measurement & Visualization　2　(2)　66-76　2014/04
Effect of Plasma Proteins in Friction of Medical Materials on PVA Hydrogel

Hiroyuki Kosukegawa, Vincent Fridrici, Emmanuelle Laurenceau, Yu Kaihong, Makoto Ohta, Philippe Kapsa

Abstract Book　2014/02
Discussions of pressure distribution in artery with stenosis and aneurysm

Yujie Li, Hitomi Anzai, Toshio Nakayama, Makoto Ohta

Abstract　2014/02
Model Study of Single Ventricular Heart Syndrome and its Treatment

Mingzi Zhang, Hitomi Anzai, Makoto Ohta

Abstract　2014/02
Study of blood flow in cerebral aneurysm with coil

Makoto Ohta, Toshio Nakayama, Guy Courbebaisse, Hitomi Anzai, Han Xiaobo, Mingzi Zhang, Yujie Li, Kaihong Yu, Carolina Vallecilla, Ricardo A. Corredor

Abstract　2014/02
The Effect of Vibration Ablation Catheter on the Temperature of the Electrode under 0.1 m/s Flow

Kaihong Yu, Makoto Ohta

Abstract　2014/02
Effect of parent artery expansion by stent placement in cerebral aneurysms. International-journal Peer-reviewed

Futoshi Mori, Sho Hanida, Makoto Ohta, Teruo Matsuzawa

Technology and health care : official journal of the European Society for Engineering and Medicine　22　(2)　209-23　2014/01/01

DOI： 10.3233/THC-140829 　

eISSN：1878-7401

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BACKGROUND: Stent placement for cerebral aneurysms leads to a decrease in blood flow. This occurs not only through the direct obstruction of flow but also by the expansion of the parent artery. The latter has been observed in several clinical studies. OBJECTIVE: The goal of this study was to clarify the effects of parent artery expansion after stent treatment on the following: 1) decrease in blood flow to an aneurysm, 2) wall shear stress (WSS), and 3) oscillatory shear index (OSI). METHODS: The parent artery geometry constructed U-shape. The aneurysm location with respect to the U-shaped parent artery was determined according to previous clinical data. We performed calculations in unsteady-state situations using constructed models. RESULTS: Parent artery expansion with stent reduces blood inflow to an aneurysm and WSS of the aneurysm wall, in addition to increasing OSI. The aneurysm position affects the decrease of the inflow rate and WSS ratio and increases the OSI ratio. Expansion causes the majority of effects on flow reduction inside an aneurysm model. Thus, the expansion effects of all samples should not be neglected. CONCLUSION: These data suggest that parent artery expansion and its effect should be measured and included in the total decrease in blood flow. Parent artery expansion may induce intimal hyperplasia, thus increasing the thickness of the aneurysm wall.
Computational simulations in the cardiovascular system. International-journal Peer-reviewed

Aike Qiao, Hai-Chao Han, Makoto Ohta, Yi Qian

TheScientificWorldJournal　2014　421061-421061　2014

DOI： 10.1155/2014/421061 　
CLASSIFICATION OF BLOOD FLOW IN CEREBRAL ANEURYSM CONSIDERING THE PARENT ARTERY CURVES Peer-reviewed

Nakayama, Toshio, Sugiyama, Shin-ichiro, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2013, Vol 3a　3A　IMECE2013-63922　2014
PIV ANALYSIS OF THE FLOW PATTERN AROUND AN ABLATION CATHETER TO OBSERVE THE FLOW EFFECT ON THE ELECTRODE Peer-reviewed

Yu, Kaihong, Yamashita, Tetsui, Shingyochi, Shigeaki, Matsumoto, Kazuo, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition, 2013, Vol 3a　IMECE2013-62791　2014

DOI： 10.1115/IMECE2013-62791 　
Observation of filling process in injection molding for fabrication of bone biomodel

Masashi Ohtake, Kei Ozawa, Makoto Ohta

IFMBE Proceedings　43　315-318　2014
Publisher: Springer Verlag
DOI： 10.1007/978-3-319-02913-9_80 　

ISSN：1680-0737

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The injection molding is one of the major process methods for fabricating specially for composite materials. This method is useful for fabricating complex shape and advanced properties of materials such as bone model, recycled plastics or building materials. A bone biomodeling requires a realistic mechanical properties and the geometry as use of mechanical tests of medical devices such as bone screw or drill. The development of bone biomodel also requires the composite materials and the method of an injection molding to produce a unified model for the tests. The mechanical properties of bone biomodeling, specially the strength or the fracture toughness have a strong relation not only to the compound condition, but also to the filling process under injection molding, because the geometry of bone has a large volume and the flow in the injection is not stable. Therefore, visualization of flow of materials in the molding is important to grasp the filling process and microstructure of the model. However, the observation of flow during the molding is hard because the molding system is, in general, not to be transparent. Ozawa et al. carried out the observation of flow behavior with tungsten fiber using micro-CT. The orientation and distribution of fibers shows the flow direction. However, the image of micro- CT scanning shows only “a result of the filling process of materials in injection”. To reveal the filling process, we develop a visible system of injection by using Poly (vinyl alcohol) (PVA) solution with good transparency and capability of changing its viscosity. Then, PVA solution can be detected by using a camera for analyzing visualization process such as particle image velocimetry (PIV). We found PVA solution is useful for investigation of relationship between flow behavior and viscosity of the material in the injection molding.
Study of parameters for evaluating the pushability of interventional devices using box-shaped blood vessel biomodels made of PVA-H or silicone. International-journal Peer-reviewed

Chang Ho Yu, Makoto Ohta, Tae Kyu Kwon

Bio-medical materials and engineering　24　(1)　961-8　2014

DOI： 10.3233/BME-130891 　

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In this paper, we investigated several parameters with effect on the compressive force to assess the mechanical properties of interventional device. We find several parameters are highly influential and others are not. In our evaluation system, we prepared a box-shaped PVA-H and silicone with realistic geometry and carried out the measurement and evaluation of the pushability by using load cell machine. The parameters of velocity, position of device in the system do not affect the compressive force, whereas the length of catheter from the tip to fixed point is one of the most influential parameters for the force. Several behaviors such as passing through the curve or slip and stop can be observed and defined using this system. The balance of the bending force and the pushing force may make the tip with behavior of slip and stop or passing thorough the curve. The investigation of the evaluation system confirmed that high reproducibility with short error bar is indicated. The observation with movie record is also an advantage of our system because the high transparency of materials with silicone and PVA-H can check the inside of artery.
Simulation of hemodynamics in artery with aneurysm and stenosis with different geometric configuration Peer-reviewed

Yujie Li, Hitomi Anzai, Toshio Nakayama, Yasumoto Shimizu, Yukihisa Miura, Aike Qiao, Makoto Ohta

Journal of Biomechanical Science and Engineering　9　(1)　2014
Publisher: Japan Society of Mechanical Engineers
DOI： 10.1299/jbse.2014jbse0003 　

ISSN：1880-9863

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In previous published research, the deployment of flow-diversion increases the intra-aneurysmal pressure by 20 mmHg in the case with a pre-aneurysm stenosis. The purpose of this study is to learn the influence to the aneurysm when a pre-aneurysm stenosis exists which may threaten people's health even more severely. In the present research, idealized models of straight and curved blood vessels with both aneurysm and pre-aneurysm stenosis were established, with altering the degree of stenosis, the distance between stenosis and aneurysm and the curvature of parent artery. As the degree of stenosis increases, the reattachment length increases in straight vessels. Different positions of reattachment points to aneurysm neck affect the flow pattern inside the aneurysm. In the model with higher degree of stenosis and smaller distance between stenosis and aneurysm, the flow pattern and the direction of vortexes inside the aneurysm are affected by the recirculation after stenosis. Driven by inertial force, reattachment length decreases as the curvature of the parent artery increases, and stream inside the aneurysm is affected only when the distance between stenosis and aneurysm is short enough. In all models, the pressure drop inside the aneurysm increases as the degree of stenosis increases, creating a lower pressure environment in the aneurysm. © 2014 The Japan Society of Mechanical Engineers.
A Study on Multiscale Model in the presence of Systemic-to-Pulmonary Shunt utilizing Open-source CFD software Palabos

M.Z. Zhang, H. Anzai, Y.J. Liu, M. Ohta

APCOM & ISCM　2013/12
Hemodynamic Numerical Simulation in Artery Complicated with both Stenosis and Aneurysm in Different Shape and Position

Y.J. Li, H. Anzai, T. Nakayama, Y. Shimizu, Y. Miura, A.K. Qiao, M. Ohta

APCOM & ISCM　2013/12
Analysis of Relationship between Lipid Environment and Protein Nanopore Properties- Toward Creation of Red Blood Cell Model with Various Membrane Strength-

Noriko Tomita, Stephan Wilkens, Liviu Movileanu, Makoto Ohta

Tenth International Conference on Flow Dynamics Proceedings　2013/11/27
Optimized Stent Invited

Makoto Ohta, Hitomi Anzai, Toshio Nakayama, Xiaobo Han, Noriko Tomita

The 10th ICFD, Sendai　580-581　2013/11/27
Membrane Channel Dynamics Depended on Lipid Environment

Noriko Tomita, Liviu Movileanu, Makoto Ohta

Tenth International Conference on Flow Dynamics Proceedings　614-615　2013/11/26
Relative residence time prolongation in intracranial aneurysms: a possible association with atherosclerosis. International-journal Peer-reviewed

Shin-ichiro Sugiyama, Kuniyasu Niizuma, Toshio Nakayama, Hiroaki Shimizu, Hidenori Endo, Takashi Inoue, Miki Fujimura, Makoto Ohta, Akira Takahashi, Teiji Tominaga

Neurosurgery　73　(5)　767-76　2013/11

DOI： 10.1227/NEU.0000000000000096 　

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BACKGROUND: Intracranial aneurysms can have atherosclerotic wall properties that may be important in predicting aneurysm history or estimating the potential risks of surgical treatments. OBJECTIVE: To investigate hemodynamic characteristics of atherosclerotic lesions in intracranial aneurysms using computational fluid dynamics. METHODS: Intraoperative video recordings of 30 consecutive patients with an unruptured middle cerebral artery aneurysm were examined to identify atherosclerotic lesions on an aneurysm wall. For computational fluid dynamics analyses, geometries of aneurysms and adjacent arteries were reconstructed from 3-dimensional rotational angiography. Transient simulations were conducted under patient-specific pulsatile inlet conditions measured by phase-contrast magnetic resonance velocimetry. Three hemodynamic wall parameters were calculated: time-averaged wall shear stress, oscillatory shear index, and relative residence time (RRT). Statistical analyses were performed to discriminate the risk factors of atherosclerotic lesion formation. RESULTS: Among 30 aneurysms, 7 atherosclerotic lesions with remarkable yellow lipid deposition were identified in 5 aneurysms. All 7 atherosclerotic lesions spatially agreed with the area with prolonged RRT. Univariate analysis revealed that male sex (P = .03), cigarette smoking (P = .047), and maximum RRT (P = .02) are significantly related to atherosclerotic lesion on the intracranial aneurysmal wall. Of those variables that influenced atherosclerotic lesion of the intracranial aneurysmal wall, male sex (P = .005) and maximum RRT (P = .004) remained significant in the multivariate regression model. CONCLUSION: The area with prolonged RRT colocalized with atherosclerotic change on the aneurysm wall. Male sex and maximum RRT were independent risk factors for atherogenesis in intracranial aneurysms.
Channel Properties of Membrane Proteins on Lipid Bilayers

Makoto Ohta, Liviu Movileanu, Noriko Tomita

AFI/TFI　2013/11
Classification of flow pattern in neck based considering the parent artery curves and stent implantation

Toshio Nakayama, Makoto Ohta

CLASSIFICATION OF FLOW PATTERN IN NECK BASED CONSIDERING THE PARENT ARTERY CURVES AND STENT IMPLANTATION　2013/11
Development of a Program for Blood flow and Cell Behaviors Based on LBM Method

Makoto Ohta, Bastien Chopard, Hitomi Anzai

AFI/TFI　2013/11
Development of Visualization System for Injection Molding by using PVA

Masashi Ohtake, Kei Ozawa, Ken Nakajima, Makoto Ohta

Tenth International Conference on Flow Dynamics Proceedings　638-639　2013/11
Influence of Ni-Ti Wire under the Shear Stress Environment on Endothelialization

Sho Matsumoto, Han Xiaobo, Hisatoshi Kobayashi, Noriko Tomita, Makoto Ohta

Tenth International Conference on Flow Dynamics Proceedings　602-603　2013/11
Optimization of stent design to increase the porosity

Yuuki Yoshida, Hitomi Anzai, Makoto Ohta

Optimization of stent design to increase the porosity　2013/11
Research of Friction and Drilling on Bio-composite Model

Makoto Ohta, Kei Ozawa, Vincent Fridrici, Philippe Kapsa

AFI/TFI　2013/11
Stagnant Blood Flow in Intracranial Aneurysms: A Possible Association with Atherosclerosis

Shin-ichiro Sugiyama, Toshio Nakayama, Kenichi Funamoto, Daichi Suzuki, Kuniyasu Niizuma, Makoto Ohta, Teiji Tominaga

Tenth International Conference on Flow Dynamics Proceedings　592-593　2013/11
The Effect of Vibration of Ablation Catheter on the Temperature of the Electrode

Kaihong Yu, Tetsui Yamanaka, Shigeaki Shigyochi, Makoto Ohta

Tenth International Conference on Flow Dynamics Proceedings　644-645　2013/11
High fidelity virtual stenting (HiFiVS) for intracranial aneurysm flow diversion: in vitro and in silico. International-journal Peer-reviewed

Ding Ma, Travis M Dumont, Hiroyuki Kosukegawa, Makoto Ohta, Xinjian Yang, Adnan H Siddiqui, Hui Meng

Annals of biomedical engineering　41　(10)　2143-56　2013/10

DOI： 10.1007/s10439-013-0808-4 　

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A flow diverter (FD) is a flexible, densely braided stent-mesh device placed endoluminally across an intracranial aneurysm to induce its thrombotic occlusion. FD treatment planning using computational virtual stenting and flow simulation requires accurate representation of the expanded FD geometry. We have recently developed a high fidelity virtual stenting (HiFiVS) technique based on finite element analysis to simulate detailed FD deployment processes in patient-specific aneurysms (Ma et al. J. Biomech. 45:2256-2263,(2012)). This study tests if HiFiVS simulation can recapitulate real-life FD implantation. We deployed two identical FDs (Pipeline Embolization Device) into phantoms of a wide-necked segmental aneurysm using a clinical push-pull technique with different delivery wire advancements. We then simulated these deployment processes using HiFiVS and compared results against experimental recording. Stepwise comparison shows that the simulations precisely reproduced the FD deployment processes recorded in vitro. The local metal coverage rate and pore density quantifications demonstrated that simulations reproduced detailed FD mesh geometry. These results provide validation of the HiFiVS technique, highlighting its unique capability of accurately representing stent intervention in silico.
Guidewire Simulator for Intravacular Surgery

K. Takashima, S. Tsuzuki, M. Umetani, K. Yoshinaka, Y. Hoshino, M. Ohta, K. Mori

UKSAES2013　2013/10
Optimization of blood flow for intracranial stent

Makoto Ohta, Hitomi Anzai, Han Xiaobo

Workshop on Flow Dynamics related to Energy, Aerospace and Material Processing　2013/09/10
Density change of smooth muscle cells in co-culture model under shear stress with spatial gradient related to the development of cerebral aneurysm

Sho Matsumoto, Han Xiaobo, Makoto Ohta, Noriko Tomita

the5th EMBO meeting advancing the life science 2013 AMSTERDAM abstracts　2013/09
Electrophysiological properties of engineered FhuA ΔC/Δ4L protein nanopore affected by lipid bilayer environment

Noriko Tomita, Liviu Movileanu, Makoto Ohta

the5th EMBO meeting advancing the life science 2013 AMSTERDAM abstracts　2013/09
Friction of Medical Materials on PVA Hydrogel in Physiological Lubrication

Hiroyuki Kosukegawa, Vincent Fridrici, Emmanuelle Laurenceau, Makoto Ohta, Philippe Kapsa

World Tribology Congress 2013　2013/09
In vitro study of ultrasound radiation force-driven twinkling sign using PVA-H gel and glass beads tissue-mimicking phantom. Peer-reviewed

Lei Liu, Kenichi Funamoto, Kei Ozawa, Makoto Ohta, Toshiyuki Hayase, Masafumi Ogasawara

Journal of medical ultrasonics (2001)　40　(3)　197-203　2013/07

DOI： 10.1007/s10396-012-0429-9 　

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The twinkling sign observed in ultrasound coded-excitation imaging (e.g., GE B-Flow) has been reported in previous research as a potential phenomenon to detect micro calcification in soft tissue. However, the mechanism of the twinkling sign has not been clearly understood yet. We conducted an in vitro experiment to clarify the mechanism of the twinkling sign by measuring a soft tissue-mimicking phantom with ultrasonic and optical devices. A soft tissue-mimicking phantom was made of poly(vinyl alcohol) hydro (PVA-H) gel and 200-μm-diameter glass beads. We applied ultrasound to the phantom using medical ultrasound diagnostic equipment to observe the twinkling sign of glass beads. Optical imaging with a laser sheet and a high-speed camera was performed to capture the scatter lights of the glass beads with and without ultrasound radiation. The scatter lights from the glass beads were quantified and analyzed to evaluate their oscillations driven by the ultrasound radiation force. The twinkling sign from the glass beads embedded in the PVA-H gel soft tissue phantom was observed in ultrasound B-Flow color imaging. The intensity and oscillation of the scattered lights from the glass beads showed significant difference between the cases with and without ultrasound radiation. The results showed a close relationship between the occurrence of the twinkling sign and the variations of the scatter lights of glass beads, indicating that ultrasound radiation force-driven micro oscillation causes the twinkling sign of micro calcification in soft tissue.
Comparison of flow patterns around stenotic area in elastic PVA-H model and in rigid-like silicone model

Yasutomo Shimizu, Masanori Kuze, Ashkan Javadzadegan, Masud Behnia, Makoto Ohta

10TH INTERNATIONAL SYMPOSIUM ON PARTICLE IMAGE VELO CIMETRY – PIV13　2013/07
Correlation between Reynolds number and stenosis morphology in eccentric and concentric artery models

Ashkan Javadzadegan, Yasutomo Shimizu, Masud Behnia, Makoto Ohta

10TH INTERNATIONAL SYMPOSIUM ON PARTICLE IMAGE VELO CIMETRY – PIV13　2013/07
In vitro strain measurements in cerebral aneurysm models for cyber-physical diagnosis. International-journal Peer-reviewed

Chaoyang Shi, Masahiro Kojima, Hitomi Anzai, Carlos Tercero, Seiichi Ikeda, Makoto Ohta, Toshio Fukuda, Fumihito Arai, Zoran Najdovski, Makoto Negoro, Keiko Irie

The international journal of medical robotics + computer assisted surgery : MRCAS　9　(2)　213-22　2013/06

DOI： 10.1002/rcs.1487 　

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BACKGROUND: The development of new diagnostic technologies for cerebrovascular diseases requires an understanding of the mechanism behind the growth and rupture of cerebral aneurysms. To provide a comprehensive diagnosis and prognosis of this disease, it is desirable to evaluate wall shear stress, pressure, deformation and strain in the aneurysm region, based on information provided by medical imaging technologies. METHODS: In this research, we propose a new cyber-physical system composed of in vitro dynamic strain experimental measurements and computational fluid dynamics (CFD) simulation for the diagnosis of cerebral aneurysms. A CFD simulation and a scaled-up membranous silicone model of a cerebral aneurysm were completed, based on patient-specific data recorded in August 2008. In vitro blood flow simulation was realized with the use of a specialized pump. A vision system was also developed to measure the strain at different regions on the model by way of pulsating blood flow circulating inside the model. RESULTS: Experimental results show that distance and area strain maxima were larger near the aneurysm neck (0.042 and 0.052), followed by the aneurysm dome (0.023 and 0.04) and finally the main blood vessel section (0.01 and 0.014). These results were complemented by a CFD simulation for the addition of wall shear stress, oscillatory shear index and aneurysm formation index. Diagnosis results using imaging obtained in August 2008 are consistent with the monitored aneurysm growth in 2011. CONCLUSION: The presented study demonstrates a new experimental platform for measuring dynamic strain within cerebral aneurysms. This platform is also complemented by a CFD simulation for advanced diagnosis and prediction of the growth tendency of an aneurysm in endovascular surgery.
Application of optimization for design of intracranial stent with blood flow reduction as objective function

Hitomi Anzai, Jean-Luc Falcone, Bastien Chopard, Makoto Ohta

WCSMO-10 10th World Congress and Structual and Multidisciplinary Optimization Program Book　2013/05
Microbial Pore-Forming Protein Properties Depended on Lipid Environment

Noriko Tomita, Liviu Movileanu, Stephan Wilkens, Makoto Ohta

NIH Tohoku University JSPS Symposium Program and Abstracts　2013/05
Does the lipid environment impact the open-state conductance of an engineered β-barrel protein nanopore? International-journal Peer-reviewed

Noriko Tomita, Mohammad M Mohammad, David J Niedzwiecki, Makoto Ohta, Liviu Movileanu

Biochimica et biophysica acta　1828　(3)　1057-65　2013/03

DOI： 10.1016/j.bbamem.2012.12.003 　

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Using rational membrane protein design, we were recently able to obtain a β-barrel protein nanopore that was robust under an unusually broad range of experimental circumstances. This protein nanopore was based upon the native scaffold of the bacterial ferric hydroxamate uptake component A (FhuA) of Escherichia coli. In this work, we expanded the examinations of the open-state current of this engineered protein nanopore, also called FhuA ΔC/Δ4L, employing an array of lipid bilayer systems that contained charged and uncharged as well as conical and cylindrical lipids. Remarkably, systematical single-channel analysis of FhuA ΔC/Δ4L indicated that most of its biophysical features, such as the unitary conductance and the stability of the open-state current, were not altered under the conditions tested in this work. However, electrical recordings at high transmembrane potentials revealed that the presence of conical phospholipids within the bilayer catalyzes the first, stepwise current transition of the FhuA ΔC/Δ4L protein nanopore to a lower-conductance open state. This study reinforces the stability of the open-state current of the engineered FhuA ΔC/Δ4L protein nanopore under various experimental conditions, paving the way for further critical developments in biosensing and molecular biomedical diagnosis.
Evaluation for Drilling Properties of Bone Models

Kei Ozawa, Yuji KATAKURA, Yukihiko SHIBATA, Gaëtan BOUVARD, Vincent FRIDRICI, Philippe KAPSA, Makoto OHTA

abstract book　2013/03
Friction of Medical Materials in Contact with PVA Hydrogel in Physiological Conditions

Hiroyuki Kosukegawa, FRIDRICI Vincent, LAURENCEAU Emmanuelle, OHTA Makoto, KAPSA Philippe

abstract book　2013/03
Study of the coil effect within an intracranial aneurysm

Guy Courbebaisse, Makoto Ohta, Toshio Nakayama

Abstract book　2013/03
Preface Peer-reviewed

Makoto Ohta, Toshiyuki Hayase

Journal of Biomechanical Science and Engineering　8　(3)　197-197　2013

DOI： 10.1299/jbse.8.197 　

ISSN：1880-9863
INFLUENCE OF PLAQUE STIFFNESS ON CHANGE OF BLOOD VESSEL GEOMETRY LEADING HEMODYNAMICAL CHANGES IN PVA-H STENOSIS MODELS Peer-reviewed

Shimizu, Yasutomo, Shida, Shuya, Funamoto, Kenichi, Hayase, Toshiyuki, Ohta, Makoto, ASME

International Mechanical Engineering Congress and Exposition - 2012, Vol 2: Biomedical and Biotechnology　IMECE2012　87073　2013

DOI： 10.1115/IMECE2012-87073 　
Bioengineering materials and conditions for obtaining low friction with PVA hydrogels Peer-reviewed

Boyko Stoimenov, Vincent Fridrici, Philippe Kapsa, Hiroyuki Kosukegawa, Makoto Ohta

Tribology Online　8　(1)　140-152　2013

DOI： 10.2474/trol.8.140 　

ISSN：1881-218X 1881-2198

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Biological materials that make up the body organs and tissues are soft, wet and visco-elastic. Hydrogels can mimic these aspects and show promise for bio-medical applications. Their tribological properties are very important for promising applications such as artificial cartilage and bio-models for endovascular surgery training. The present study investigates the friction of polyvinyl alcohol (PVA) hydrogel against nine different metallic and non-metallic bio-compatible engineering materials likely to occur as countermaterials in these two applications. All the materials exhibited a characteristic velocity-dependent peak friction coefficient. Comparing the peaks, we find that lowest peak friction coefficient is produced by ceramics and glass (μ &lt 0.05), followed by metal alloys (μ &lt 0.05-0.08) and highest for polymers (0.4 &lt μ &lt 1.5), including PTFE which typically has very low-adhesion. Our results suggest that to achieve low friction, polymers should be avoided as a counter-material to PVA-hydrogels. It is also shown that PVA surface roughness is critical for achieving early transition to elasto-hydrodynamic lubrication and low friction, as shown in our comparative calculations with two different values of surface roughness of the gel. In the mixed lubrication region, the general trend is for friction to increase with roughness of the counterbody, but internal damping properties and adhesion also play important role, as shown by a simple linear model fit. Copyright © 2013 Japanese Society of Tribologists.
Flow observations in elastic stenosis biomodel with comparison to rigid-like model. International-journal Peer-reviewed

Yasutomo Shimizu, Ashkan Javadzadegan, Toshiyuki Hayase, Makoto Ohta

Technology and health care : official journal of the European Society for Engineering and Medicine　21　(4)　305-14　2013

DOI： 10.3233/THC-130725 　

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BACKGROUND: Plaques in blood vessels exhibit a wide range of stiffness depending on disease conditions: stiffness is an important factor in plaque behavior. The geometrical change in plaque based on its behavior can affect blood flow patterns. Thus, it is important to study both blood flow and deformation of plaques and blood vessels. OBJECTIVE: This study aims to identify the differences in flow conditions between in vitro models to discuss experimental materials for arterial wall and flow observation. METHODS: In order to observe the blood flow pattern and plaque deformation simultaneously, a PVA-H stenosis model was used. In addition, a silicone model was also used as a rigid-like model for comparison with the PVA-H model. PIV was employed to measure the flow velocity distribution and determine the flow levels in the models. RESULTS: PVA-H model exhibits expansion with an increase in upstream pressure and silicone model maintains the diameter. The expansion depends on their mechanical properties and influences flow conditions such as velocity changes and RAP in the parent artery. The balance between the expansion and change in flow conditions determines the final geometries of PVA-H model and flow pattern. CONCLUSIONS: The results suggest that the stiffness measurement for blood vessels and plaques such as ultrasound measurements would be important for accurate treatments.
Correlation between Reynolds number and eccentricity effect in stenosed artery models. International-journal Peer-reviewed

Ashkan Javadzadegan, Yasutomo Shimizu, Masud Behnia, Makoto Ohta

Technology and health care : official journal of the European Society for Engineering and Medicine　21　(4)　357-67　2013

DOI： 10.3233/THC-130736 　

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BACKGROUND: Flow recirculation and shear strain are physiological processes within coronary arteries which are associated with pathogenic biological pathways. Distinct Quite apart from coronary stenosis severity, lesion eccentricity can cause flow recirculation and affect shear strain levels within human coronary arteries. OBJECTIVE: The aim of this study is to analyse the effect of lesion eccentricity on the transient flow behaviour in a model of a coronary artery and also to investigate the correlation between Reynolds number (Re) and the eccentricity effect on flow behaviour. METHODS: A transient particle image velocimetry (PIV) experiment was implemented in two silicone based models with 70% diameter stenosis, one with eccentric stenosis and one with concentric stenosis. RESULTS: At different times throughout the flow cycle, the eccentric model was always associated with a greater recirculation zone length, maximum shear strain rate and maximum axial velocity; however, the highest and lowest impacts of eccentricity were on the recirculation zone length and maximum shear strain rate, respectively. Analysis of the results revealed a negative correlation between the Reynolds number (Re) and the eccentricity effect on maximum axial velocity, maximum shear strain rate and recirculation zone length. CONCLUSIONS: As Re number increases the eccentricity effect on the flow behavior becomes negligible.
Friction Properties of Medical Metallic Alloys on Soft Tissue-Mimicking Poly(Vinyl Alcohol) Hydrogel Biomodel Peer-reviewed

Kosukegawa, Hiroyuki, Fridrici, Vincent, Kapsa, Philippe, Sutou, Yuji, Adachi, Koshi, Ohta, Makoto

Tribology Letters　51　(3)　311-321　2013

DOI： 10.1007/s11249-013-0165-3 　
Modeling Flow Diverter Stent using Porous Media

Makoto Ohta, Yukihisa Miura, Hitomi Anzai, Toshio Nakayama

Abstract　2012/10
Experimental Validation of FEA-Based Workflow to Simulate Flow Diverting Stent Deployment in Intracranial Aneurysms

Hui Meng, Travis Dumont, Hiroyuki Kosukegawa, Ding Ma, Makoto Ohta

Abstract　2012/10
Stent designs for efficient reduction of intra-aneurismal flow with various aneurysms

Hitomi Anzai, Jean-Luc Falcone, Bastien Chopard, Makoto Ohta

Abstract　2012/10
Classification of Flow pattern in neck based on parent artery configuration and optimized stent implantation

Toshio Nakayama, Shinkyu Jeong, Karkenahalli Srinivas, Makoto Ohta

Abstract　2012/10
Hemodynamics Effect of Y-Configuration Stenting on Basilar Tip Aneurysm

Masahiro Kojima, Toshio Fukuda, Keiko Irie, Makoto Negoro, Makoto Ohta

Abstract　2012/10
Ultrasound Radiation Force Driven B-Flow Twinkling Sign for Microcalcification Detection

L. Liu, K. Funamoto, K. Ozawa, M. Ohta, T. Hayase, M. Ogasawara

Proceedings of the 12th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration (AFI/TFI-2012)　86-87　2012/09/20
Electrophysiological Properties of Bacterial Membrane Channel Proteins Depending on Lipid Component and Bilayer Stability

Noriko Tomita, Liviu Movileanu, Makoto Ohta

Proceedings of [Ninth International Conference on Flow Dynamics　2012/09/20
Effect of the Aspect Ratio of Cerebral Aneurysms on Blood Flow Reduction after Optimized Stent Placement

Toshio Nakayama, Shinkyu Jeong, Karkenahalli Srinivas, Makoto Ohta

Proceedings of Ninth International Conference on Flow Dynamics　424-425　2012/09/20
Optimum Design of Flow Diverter Stent Associated with Arterial Geometries

Hitomi Anzai, Jean-Juc Falcone, Bastien Chopard, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　2012/09
Properties of N-butyl cyanoacrylate-iodized oil mixtures for arterial embolization: in vitro and in vivo experiments. International-journal Peer-reviewed

Chiaki Takasawa, Kazumasa Seiji, Kenichi Matsunaga, Toshio Matsuhashi, Makoto Ohta, Shuya Shida, Kei Takase, Shoki Takahashi

Journal of vascular and interventional radiology : JVIR　23　(9)　1215-1221　2012/09

DOI： 10.1016/j.jvir.2012.06.022 　

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PURPOSE: To examine the properties of N-butyl cyanoacrylate (NBCA) and iodized oil (lipiodol [Lip]) in vitro and in vivo for safe and effective embolization. MATERIALS AND METHODS: Viscosity, polymerization time, and diffusing capacity were evaluated according to the NBCA/Lip ratio in vitro. Additionally, the effect of the NBCA/Lip ratio on arterial embolization was evaluated in vivo; various ratios of NBCA/Lip were injected into the renal arteries of adult beagles, after which the embolization effect following transcatheter arterial embolization was quantitatively investigated histopathologically and using computed tomography (CT) volumetry. RESULTS: The viscosity of NBCA/Lip increased, polymerization time was prolonged, and diffusing capacity increased as the NBCA density decreased. As the NBCA density decreased, embolic material was recognized in smaller diameter arteries, and embolization of a larger vascular bed was accomplished. The NBCA/Lip mixture with a low density of NBCA was located more peripherally from the catheter tip, and embolization of more peripheral and smaller diameter arteries was achieved. CONCLUSIONS: The relationships of properties of NBCA/Lip in vitro and embolization effects in vivo of various ratios of NBCA/Lip were quantitatively examined and compared. The results of this study are useful for safe and effective embolization.
Comparison between Agarose gel and PVA-H Biomodels for Evaluation of Ablation Catheter

Kaihong Yu, Tetsuya Yamashita, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　2012/09
Size Validation of an Adrenal Vein Model for Development of an In Vitro Model with Realistic Geometrical Structure

Yusuke Hoshino, Kei Takase, Kazumasa Seiji, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　620-622　2012/09
Flow Analysis in Cerebral Aneurysm Model with Transparent Coils Placement

Masanori Kuze, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　656-657　2012/09
Relationship between Fluid Shear Stress and the Phenotype Change of Smooth Muscle Cells in a Co-culture Model

Xiaobo Han, Naoya Sakamoto, Noriko Tomita, Meng Hui, Masaaki Sato, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　614-615　2012/09
Friction and thermal Properties in Drilling of Bone Biomodels

Kei Ozawa, Yuji Katakura, Yukihiko Shibata, Philippe Kapsa, Vincent Fridrici, Gaetan Bouvard, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　584-585　2012/09
Neumerical and Experimental Study of Flow in Stenosis models with Several Mechanical Properties

Yasutomo Shimizu, Shuya Shida, Ashkan Javadzadegan, Kenichi Funamoto, Toshiyuki Hayase, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　422-423　2012/09
Measurement of Pressure Drop for Modeling Intracranial Flow Diverter Stent Using Porous Medium

Yukihisa Miura, Hitomi Anzai, Toshio Nakayama, Toshiyuki Hayase, Makoto Ohta

Proceedings Ninth International Conference on Flow Dynamics　586-587　2012/09
Simulation of Hemodynamics in Artery with Aneurysm and Stenosis

Yujie Li, Hitomi Anzai, Toshio Nakayama, Yasutomo Shimizu, Yukihisa miura, Aike Qiao, Makoto Ohta

不明　410-411　2012/09
A Development of Lattice Boltzmann Model and Lumped Parameter Model Connection for Cardiovascular Multiscale Analysis

Mingzi Zhang, Hitomi Anzai, Youjun Liu, Makoto Ohta

不明　412-413　2012/09
Tribology of Medical Materials on PVA-H Biomodel

Hiroyuki Kosukegawa, Makoto Ohta, Vincent Fridrici, Philippe Kapsa

不明　102-103　2012/09
Characterization of Design of Stent Strut Positioning using LBM Method

Makoto Ohta, Bastien Chopard, Hitomi Anzai

不明　98-99　2012/09
Channel Properties of Membrane Proteins on Lipid Bilayer

Makoto Ohta, Liviu Movileanu, Noriko Tomita

不明　100-101　2012/09
Oscillatory and Stagnant Flow in Intracranial Aneurysms: A Possible Association with Atherosclerosis

Shin-ichiro Sugiyama, Hiroaki Shimizu, Toshio Nakayama, Makoto Ohta, Teiji Tominaga

不明　120-121　2012/09
Computational fluid dynamic analysis following recurrence of cerebral aneurysm after coil embolization. International-journal Peer-reviewed

Keiko Irie, Hitomi Anzai, Masahiko Kojima, Naomi Honjo, Makoto Ohta, Yuichi Hirose, Makoto Negoro

Asian journal of neurosurgery　7　(3)　109-15　2012/07

DOI： 10.4103/1793-5482.103706 　

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Hemodynamic factors are thought to play important role in the initiation, growth, and rupture of cerebral aneurysms. However, hemodynamic features in the residual neck of incompletely occluded aneurysms and their influences on recanalization are rarely reported. This study characterized the hemodynamics of incompletely occluded aneurysms that had been confirmed to undergo recanalization during long-term follow-up using computational fluid dynamic analysis. A ruptured left basilar-SCA aneurysm was incompletely occluded and showed recanalization during 11 years follow-up period. We retrospectively characterized on three-dimensional MR angiography. After subtotal occlusion, the flow pattern, wall shear stress (WSS), and velocity at the remnant neck changed during long-term follow-up period. Specifically, high WSS region and high blood flow velocity were found near the neck. Interestingly, these area of the remnant neck coincided with the location of aneurysm recanalization. High WSS and blood flow velocity were consistently observed near the remnant neck of incompletely occluded aneurysm, prone to future recanalization. It will suggest that hemodynamic factors may play important roles in aneurismal recurrence after endovascular treatment.
The Design Characteristics Extracted From an Optimal Flow Diverter in an Ideal Side-wall Aneurysm Using Lattice Boltzmann Method

Hitomi Anzai, Jean-Luc Falcone, Bastien Chopard, Makoto Ohta

不明　2012/07
PIV Measurement of Inflow through Cerebral Aneurysmal Neck of PVA-H Biomodel with Compliant Wall

Shuya Shida, Makoto Ohta

不明　2012/07
細径光ファイバ圧力センサを用いた灌流圧測定機能を有する臓器灌流カテーテル

引地広介, 松永忠雄, 早津幸弘, 佐藤充, 深谷昌宏, 飯沼貴章, 太田信, 齋木佳克, 芳賀洋一

第51回日本生体医工学会大会論文集　51st　2012/05
未破裂脳動脈流の破裂リスクに関する３次元可視化システムを用いたCFD解析の試み Invited Peer-reviewed

入江恵子, 太田信, 安西眸, 廣瀬雄一

日本脳神経CI学会論文　33　(2)　119-125　2012/02
Preface

Ohta, M., Hayase, T.

Journal of Biomechanical Science and Engineering　7　(SPECIALISSUE.3)　197-197　2012
3F0948 Molecular basis of staphylococcal bi-component pore forming toxin(Membrane Proteins,Oral Presentation)

Tanaka Yoshikazu, Yamashita Daichi, Yamashita Keitaro, Kawai Yuka, Kaneko Jun, Tomita Noriko, Ohta Makoto, Kamio Yoshiyuki, Yao Min, Tanaka Isao

Seibutsu Butsuri　52　S66　2012
Publisher: The Biophysical Society of Japan General Incorporated Association
DOI： 10.2142/biophys.52.S66_3 　
Hemodynamic Study for New Stent Design with Mesh-Typed Stents in a Cerebral Aneurysm Model using PIV Peer-reviewed

Yu, Chang-Ho, Ohta, Makoto, Kwon, Tae-Kyu, IEEE

2012 12th International Conference on Control, Automation and Systems (Iccas)　2012
DEVELOPMENT OF A METHODOLOGY FOR ADAPTATION OF REFRACTIVE INDEX UNDER CONTROLLING KINEMATIC VISCOSITY FOR PIV Peer-reviewed

Shida, Shuya, Kosukegawa, Hiroyuki, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition 2011, Vol 2　2012
CONTROL OF WALL THICKNESS OF BLOOD VESSEL BIOMODEL MADE OF POLY (VINYL ALCOHOL) HYDROGEL BY A THREE-DIMENSIONAL-ROTATING SPIN DIP-COATING METHOD Peer-reviewed

Kosukegawa, Hiroyuki, Kiyomitsu, Chihaya, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition 2011, Vol 2　2012
QUANTITATIVE ANALYSIS OF SUBUNIT MISMATCH ARRANGEMENT IN STAPHYLOCOCCAL GAMMA-HEMOLYSIN HETEROHEPTAMERIC TRANSMEMBRANE PORE Peer-reviewed

Tomita, Noriko, Abe, Kazuyo, Ohta, Makoto, ASME

Proceedings of the Asme International Mechanical Engineering Congress and Exposition 2011, Vol 2　IMECE2011　63645　2012
Optimization of flow diverters for cerebral aneurysms Peer-reviewed

Anzai, Hitomi, Ohta, Makoto, Falcone, Jean-Luc, Chopard, Bastien

Journal of Computational Science　3　(1-2)　1-7　2012

DOI： 10.1016/j.jocs.2011.12.006 　
Membrane-damaging activity against various phospholipid liposomes by γ-hemolysin, staphylococcal two-component pore-forming cytolysin Peer-reviewed

Noriko Tomita, Yoshiyuki Kamio, Makoto Ohta

Journal of Biomechanical Science and Engineering　7　(3)　292-304　2012

DOI： 10.1299/jbse.7.292 　

ISSN：1880-9863

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Staphylococcal γ-hemolysin (Hlg) is a two-component cytolysin, which consists of LukF (Hlg1) and Hlg2. Our previous study has suggested that LukF and Hlg2 are alternatively arranged on the human erythrocyte membrane and form a ring-shaped heterooligomeric transmembrane pore with a functional diameter of approximately 2 nm. Quantitative image analyses using high-resolution transmission electron microscopy have revealed that LukF and Hlg2 tend to be arranged in several mismatch patterns. Several previous studies have reported that the LukF component has a binding pocket for phosphatidylcholine. In the present study, membrane- damaging activities by Hlg were investigated by using carboxyfluoresceine (CF)-loading liposomes consisting of mammalian erythrocyte phospholipids or one kind of phospholipid. Our results revealed that Hlg shows membrane-damaging activities on horse, rabbit and human erythrocyte total phospholipid liposomes. Such activity was closely related to the ratio of phosphatidylcholine. Hlg showed membrane-damaging activity against phosphatidylcholine liposome by formation of ring-shaped pore complex and cluster. Besides, it was revealed that Hlg could target cardiolipin, which is not included in the mammalian erythrocyte membrane, but exists in the bacterial cytoplasmic membrane and in the inner mitochondrial membrane of mammal cell. The results suggest that Hlg has the potential to recognize several phospholipids in both erythrocyte and non-erythrocyte membranes and induce cytolysis not only of mammalian cells but also of bacterial cells by the formation of pores and clusters. These novel findings will contribute to the elucidation of mutual actions between cytotoxicity protein and phospholipids, and eventually lead to the development of a treatment for staphylococcal infection. © 2012 by JSME.
Observation of the expansion behavior and quantitative evaluation of elastic recoil of a balloon-expandable stent in three dimensions using a Micro-CT system. International-journal Peer-reviewed

Futoshi Mori, Toshio Nakayama, Teruo Matsuzawa, Makoto Ohta

Technology and health care : official journal of the European Society for Engineering and Medicine　20　(4)　305-15　2012

DOI： 10.3233/THC-2012-0680 　

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Percutaneous transluminal coronary angioplasty (PTCA) with stent implantation is widely used for the treatment of coronary stenosis. However, restenosis after stent implantation frequently reported by intravascular ultrasound evaluation. This may occur because of the reduced luminal area after implantation, insufficient stent expansion, or by the elastic recoil of the stent (ERS). Quantitative evaluation of stent expanding should provide further information on how to decrease the incidence of re-stenosis. Many previous studies have observed stent properties in 2D. However, the stent geometry is changed in 3D space, and 3D measurements will provide further information on factors such as the risk for asymmetric ERS. We performed 3D reconstruction using high spatial resolution images obtained with a Micro-CT system to observe the 3D expansion behavior of a test stent and quantitatively evaluate ERS. The expansion behavior of each structural component of the stent varied, as did the ERS and eccentricity. ERS ranged from 2.4% to 9.2% during observation form proximal and distal positions in each component. The greatest difference in ERS between 2D and 3D measurements was 5.2%. 3D measurements provide more information on ERS than 2D measurements. Our result shows the importance of the observation, and the evaluation by three dimensions.
A steady flow analsys on a cerebral aneurysm model with several stents for new stent design using PIV Peer-reviewed

Yu, Chang-Ho, Matsumoto, Kaoru, Shida, Shuya, Kim, Dong Joon, Ohta, Makoto

Journal of Mechanical Science and Technology　26　(5)　1333-1340　2012

DOI： 10.1007/s12206-012-0322-x 　
A Cyper-Physical System for Strain Measurements in the Cerebral Aneurysm Models Peer-reviewed

Shi, Chaoyang, Kojima, Masahiro, Tercero, Carlos, Anzai, Hitomi, Ohta, Makoto, Ooe, Katsutoshi, Ikeda, Seiichi, Fukuda, Toshio, Arai, Fumihito, Negoro, Makoto, Irie, Keiko, Kwon, Guiryong, IEEE, Robotics Society of Japan

2012 Ieee/rsj International Conference on Intelligent Robots and Systems (Iros)　IROS 2012　4137-4142　2012

DOI： 10.1109/IROS.2012.6385754 　
Detection of Microcalcification in Soft Tissue Employing B-Flow ”Twinkling” Sign

L. Liu, K. Ozawa, K. Funamoto, M. Ohta, T. Hayase, M. Ogasawara

Proceedings of the 11th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration (AFI/TFI-2011)　94-95　2011/11/10
Cluster-forming property correlated with hemolytic activity by staphylococcal γ-hemolysin transmembrane pores. International-journal Peer-reviewed

Noriko Tomita, Kazuyo Abe, Yoshiyuki Kamio, Makoto Ohta

FEBS letters　585　(21)　3452-6　2011/11/04

DOI： 10.1016/j.febslet.2011.09.041 　

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Staphylococcal γ-hemolysin (Hlg) is a pore-forming toxin consisting of two separate components, LukF (34kDa) and Hlg2 (32kDa). Here we show that Hlg pores aggregate and form clusters on human erythrocyte membranes in association with increasing hemolytic activity. Quantitative analysis using transmission electron microscopy and image processing revealed that the formation of single pores and clusters is related to the release of potassium ions and of hemoglobin from erythrocytes, respectively. This is the first study to suggest a novel and unique property which can facilitate hemolysis by the cluster formation of Hlg pores.
Crystal structure of the octameric pore of staphylococcal γ-hemolysin reveals the β-barrel pore formation mechanism by two components. International-journal Peer-reviewed

Keitaro Yamashita, Yuka Kawai, Yoshikazu Tanaka, Nagisa Hirano, Jun Kaneko, Noriko Tomita, Makoto Ohta, Yoshiyuki Kamio, Min Yao, Isao Tanaka

Proceedings of the National Academy of Sciences of the United States of America　108　(42)　17314-9　2011/10/18

DOI： 10.1073/pnas.1110402108 　

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Staphylococcal γ-hemolysin is a bicomponent pore-forming toxin composed of LukF and Hlg2. These proteins are expressed as water-soluble monomers and then assemble into the oligomeric pore form on the target cell. Here, we report the crystal structure of the octameric pore form of γ-hemolysin at 2.5 Å resolution, which is the first high-resolution structure of a β-barrel transmembrane protein composed of two proteins reported to date. The octameric assembly consists of four molecules of LukF and Hlg2 located alternately in a circular pattern, which explains the biochemical data accumulated over the past two decades. The structure, in combination with the monomeric forms, demonstrates the elaborate molecular machinery involved in pore formation by two different molecules, in which interprotomer electrostatic interactions using loops connecting β2 and β3 (loop A: Asp43-Lys48 of LukF and Lys37-Lys43 of Hlg2) play pivotal roles as the structural determinants for assembly through unwinding of the N-terminal β-strands (amino-latch) of the adjacent protomer, releasing the transmembrane stem domain folded into a β-sheet in the monomer (prestem), and interaction with the adjacent protomer.
Computational fluid dynamics of carotid arteries after carotid endarterectomy or carotid artery stenting based on postoperative patient-specific computed tomography angiography and ultrasound flow data. International-journal Peer-reviewed

Hitoshi Hayase, Koji Tokunaga, Toshio Nakayama, Kenji Sugiu, Ayumi Nishida, Seiji Arimitsu, Tomohito Hishikawa, Shigeki Ono, Makoto Ohta, Isao Date

Neurosurgery　68　(4)　1096-101　2011/04

DOI： 10.1227/NEU.0b013e318208f1a0 　

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BACKGROUND: There are significant differences in the postoperative morphological and hemodynamic conditions of the carotid arteries between carotid artery stenting (CAS) and endarterectomy (CEA). OBJECTIVE: To compare the postoperative rheological conditions after CAS with those after CEA with patch angioplasty (patch CEA) through the use of computational fluid dynamics (CFD) based on patient-specific data. METHODS: The rheological conditions in the carotid arteries were simulated in 2 patients after CAS and in 2 patients after patch CEA by CFD calculations. Three-dimensional reconstruction of the carotid arteries was performed with the images obtained with computed tomography angiography. The streamlines and wall shear stress (WSS) were calculated by a supercomputer. Adequate boundary conditions were determined by comparing the simulation results with ultrasound flow data. RESULTS: CFD was successfully calculated for all patients. The differences between the flow velocities of ultrasound data and those of the simulation results were limited. In the streamline analysis, the maximum flow velocities in the internal carotid artery after patch CEA were around two-thirds of those after CAS. Rotational slow flow was observed in the internal carotid artery bulb after patch CEA. WSS analysis found regional low WSS near the outer wall of the bulb. High WSS was observed at the distal end of the arteriotomy after patch CEA and at the residual stenosis after CAS. CONCLUSION: CFD of postoperative carotid arteries disclosed the differences in streamlines and WSS between CAS and patch CEA. CFD may allow us to obtain adequate rheological conditions conducive to achieving the best clinical results.
PIV measured hemodynamic study with several stents in a cerebral aneurysm model for new stent design Peer-reviewed

Chang-Ho Yu, Shuya Shida, Kaoru Matsumoto, Makoto Ohta

ASME-JSME-KSME 2011 Joint Fluids Engineering Conference, AJK 2011　1　(D)　2073-2080　2011

DOI： 10.1115/AJK2011-19025 　

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The rupture of an aneurysm can lead to a subarachnoid hemorrhage, which can be a fatal illness in a large percentage of cases. In treating aneurysm intravascular stenting is thought as a better option compared with clipping treatment. The treatment of cerebral aneurysm with a porous stent also has recently proposed as a minimally invasive way to prevent rupture and favor coagulation mechanism inside aneurysm. The analysis of a flow pattern with and without stent in cerebral aneurysm model was performed with Particle Image Velocimetry (PIV). Three types of stents were used in the present investigation and the porosity of stent 1, 2 and 3 is 80%, 74% and 64 %, respectively. Reduced velocity, smaller average vorticity magnitude and different flow patterns inside aneurysm are observed when the three different proposed stents are used. The stent 3 (Porosity =64%) decrease the magnitude of the velocity by 98% and change the flow pattern in the aneurysm. Our results show that not only the role of the porosity but also the stent shape affect the flow and help us understand the characteristic of stent designs. Copyright © 2011 by ASME.
Experimental analysis on MR fluid channel flow dynamics with complex fluid-wall interactions Peer-reviewed

Nishiyama, Hideya, Takana, Hidemasa, Shinohara, Keisuke, Mizuki, Kotoe, Katagiri, Kazunari, Ohta, Makoto

Journal of Magnetism and Magnetic Materials　323　(10)　2011

DOI： 10.1016/j.jmmm.2010.11.033 　
Friction properties of PVA-H/steel ball contact under water lubrication conditions Peer-reviewed

Mamada, Keisuke, Kosukegawa, Hiroyuki, Fridrici, Vincent, Kapsa, Philippe, Ohta, Makoto

Tribology International　44　(7-8)　757-763　2011

DOI： 10.1016/j.triboint.2010.12.014 　
Friction Properties of Poly(vinyl alcohol) Hydrogel: Effects of Degree of Polymerization and Saponification Value Peer-reviewed

Mamada, Keisuke, Fridrici, Vincent, Kosukegawa, Hiroyuki, Kapsa, Philippe, Ohta, Makoto

Tribology Letters　42　(2)　2011

DOI： 10.1007/s11249-011-9768-8 　
Probabilistic study on subunit mismatch arrangement in staphylococcal γ-hemolysin heteroheptameric transmembrane pore Peer-reviewed

Noriko Tomita, Kazuyo Abe, Jun Kaneko, Yoshiyuki Kamio, Makoto Ohta

Journal of Biomechanical Science and Engineering　6　(4)　286-298　2011

DOI： 10.1299/jbse.6.286 　

ISSN：1880-9863

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Staphylococcal γ-hemolysin (Hlg), consists of two separate proteins, Hlg1 (LukF) of 34 kDa and Hlg2 of 32 kDa, which cooperatively lyse mammalian erythrocytes. Hlg is an illustrative molecule for the study of the assembly and membrane insertion of transmembrane proteins having the unique characteristic of being composed of two separate proteins. Our previous studies revealed that LukF and Hlg2 assemble alternately on a membrane to form ring-shaped heteroheptameric transmembrane pores, which form funnel-shaped structure with a subunit mismatch arrangement in which the distance between two of the adjacent subunits is significant larger than the others. In the present study, further analysis of the subunit mismatch arrangement in Hlg heteroheptameric pores was conducted by two-dimensional (2-D) image analysis. The distances between two adjacent subunits were numbered according to the size of the distance between adjacent subunits, and how each distance was arranged in the pore was investigated. As a result, the following results were clarified: (1) Not all distances between two adjacent subunits are even. This indicates that a mismatch arrangement exists at not only one site but also at other sites. (2) There is a high probability leading several patterns of mismatch arrangement. (3) These mismatch patterns tend to be polarized into a region in which the distance between subunits is great and a region in which such distance is small. The probabilistic analysis used in this study revealed that there is the intrinsic geometry with subunit arrangements in the heteroheptameric pore consists of two differential subunits. © 2011 by JSME.
黄色ブドウ球菌γヘモリジンが形成するヘテロヘプタマー膜孔複合体の立体構造予測と分子配置解析 Invited Peer-reviewed

冨田典子, 安西眸, 安部和代, 太田信

顕微鏡　45　(4)　223-228　2010/12

ISSN：1349-0958
多機能なカテーテル評価のためのPVA-Hモデルを用いた循環路システムの開発 Peer-reviewed

橋田葉子, 小助川博之, 信太宗也, 斉木佳克, 松永忠雄, 戸津健太郎, 芳賀洋一, 太田信

日本人工臓器学会　39　(2)　58　2010/11/18

ISSN：0300-0818
Detection of Microcalcification in Soft Tissue

L. Liu, M. Ogasawara, K. Ozawa, K. Funamoto, M. Ohta, T. Hayase

Proceedings of the tenth International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration (AFI/TFI-2010)　80-81　2010/11/02
管内MR流体流動における壁面相互作用に関する基礎特性

西山秀哉, 高奈秀匡, 篠原圭介, 水木琴絵, 片桐一成, 太田信

日本レオロジー学会第58回レオロジー討論会講演要旨集　312-313　2010/10/06
3P012 Subunit arrangement analysis of staphylococcal γ-hemolysin heteroheptameric transmembrane pore(Protein: Structure,The 48th Annual Meeting of the Biophysical Society of Japan)

Tomita Noriko, Abe Kazuyo, Anzai Hotomi, Ohta Makoto

Seibutsu Butsuri　50　(2)　S146-S147　2010
Publisher: The Biophysical Society of Japan General Incorporated Association
DOI： 10.2142/biophys.50.S146_6 　
Jet-Fluid Effects on the Stented-Flow Structure in the Cavity of Cerebral Aneurysm Peer-reviewed

Hirabayashi, Miki, Ohta, Makoto, Kojima, Hiroaki, Oiwa, Kazuhiro, Ruefenacht, Daniel A., Chopard, Bastien

Biophysical Journal　98　(3)　2010

DOI： 10.1016/j.bpj.2009.12.2194 　
Development of an in vitro tracking system with poly (vinyl alcohol) hydrogel for catheter motion Peer-reviewed

ChangHo YU, Hiroyuki Kosukegawa, Keisuke Mamada, Kanju Kuroki, Kazuto Takashima, Kiyoshi Yoshinaka, Makoto Ohta

Journal of Biomechanical Science and Engineering　5　(1)　11-17　2010

DOI： 10.1299/jbse.5.11 　

ISSN：1880-9863

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Vascular diseases, such as ischemic heart disease, infarction, aneurysms, stroke and stenosis are a leading cause of serious long-term disability and their mortality rate is as high as that of cancers in many countries. Recently, neurovascular intervention using catheters is a minimally-invasive endovascular technique used to treat vascular disease of the brain, and a navigation system for catheters has been developed to facilitate surgical planning and to provide intra-operative assistance. Since the mechanical properties of a catheter play an important role in reaching the targeted disease, tracking of catheter movement during endovascular treatment may be useful to increase confirmation of the rate of successful operation. In this study, we developed an in vitro tracking system for catheter motion using poly (vinyl alcohol) hydrogel (PVA-H) to mimic an arterial wall. The employed models were made of PVA-H, which is sufficiently transparent to permit observation of catheter movement in the artery. This system is expected to contribute to validation of computer-based navigation systems for surgical assistance. © 2010 by JSME.
Anisotropic In Vitro Vessel Model Using Poly(vinyl Alcohol) Hydro Gel and Mesh Material Peer-reviewed

Liu, Lei, Kosukegawa, Hiroyuki, Ohta, Makoto, Hayase, Toshiyuki

Journal of Applied Polymer Science　116　(4)　2242-2250　2010

DOI： 10.1002/app.31687 　
Two-Dimensional Optimization of a Stent for an Aneurysm Peer-reviewed

Srinivas, K., Townsend, S., Lee, C. J., Nakayama, T., Ohta, M., Obayashi, S., Yamaguchi, T.

Journal of Medical Devices-Transactions of the Asme　4　(2)　021003-1-021003-7　2010

DOI： 10.1115/1.4001861 　
DEVELOPMENT OF STENT STRUT PATTERN FOR CEREBRAL ANEURYSM Peer-reviewed

Nakayama, Toshio, Jeong, Shinkyu, Karkenahalli, Srinivas, Ohta, Makoto, ASME

Proceedings of the Asme Fluids Engineering Division Summer Conference - 2010 - Vol 1, Pts a-C　FEDSM/ICNMM 2010　30592　2010
MECHANICAL PROPERTIES OF TUBE-SHAPED POLY (VINYL ALCOHOL) HYDROGEL BLOOD VESSEL BIOMODEL Peer-reviewed

Kosukegawa, Hiroyuki, Shida, Shuya, Hashida, Yoko, Ohta, Makoto, ASME

Proceedings of the Asme Fluids Engineering Division Summer Conference - 2010 - Vol 1, Pts a-C　FEDSM/ICNMM 2010　30892　2010
THE EFFECT OF 3D VISUALIZATION ON OPTIMAL DESIGN FOR STRUT POSITION OF INTRACRANIAL STENT Peer-reviewed

Anzai, Hitomi, Nakayama, Toshio, Takeshima, Yuriko, Ohta, Makoto, ASME

Proceedings of the Asme Fluids Engineering Division Summer Conference - 2010 - Vol 1, Pts a-C　FEDSM/ICNMM 2010　30591　2010
Vertebrobasilar junction fenestration with dumbbell-shaped aneurysms formation: computational fluid dynamics analysis. International-journal Peer-reviewed

Yuang-Seng Tsuei, Yasushi Matsumoto, Makoto Ohta, Toshio Nakayama, Masayuki Ezura, Akira Takahashi

Surgical neurology　72 Suppl 2　S11-9-19　2009/12

DOI： 10.1016/j.surneu.2009.05.026 　

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BACKGROUND: We report 8 rare cases of paired ANs involving fenestrated vertebrobasilar junction and demonstrate the flow patterns of the paired ANs by qualitative CFD analysis in 5 cases. METHODS: Two-dimensional and 3-dimensional angiographic features of 8 cases were reviewed. Nine patient-specific geometries of CFD models in 5 cases were created for flow analysis. RESULTS: All 8 cases had 2 ANs, one large and the other small, projecting to the opposite sides at the proximal end of fenestrated vertebrobasilar junction. The different angiographic findings between right VA and left VA suggested the different hemodynamic characteristics of the respective VAs. Computational fluid dynamics analysis also demonstrated that the inflows of these paired ANs were different between right VA and left VA. Flow simulations by CFD were consistent with angiographic findings. CONCLUSION: Intrinsic wall defects at fenestrated vertebrobasilar junction and specific hemodynamic stresses from 2 inflows may contribute to the formation of a pair of dumbbell-shaped ANs.
生体材料を活用した管内MR流体流動の動的応答と高機能化

篠原圭介, 水木琴絵, 片桐一成, 高奈秀匡, 太田信, 西山秀哉

日本混相流学会年会講演会2009講演論文集　116-117　2009/08/07
3TA5-05 Three-dimentional structure analysis of staphylococcal γ-hemolysin heteroheptameric transmembrane pore complex(The 47th Annual Meeting of the Biophysical Society of Japan)

Tomita Noriko, Anzai Hitomi, Kaneko Jun, Kamio Yoshiyuki, Ohta Makoto

Seibutsu Butsuri　49　S58-S59　2009
Publisher: The Biophysical Society of Japan General Incorporated Association
DOI： 10.2142/biophys.49.S58_5 　
Evaluation of Compliance of Poly (vinyl alcohol) Hydrogel for Development of Arterial Biomodeling Peer-reviewed

Kosukegawa, H., Mamada, K., Kuroki, K., Liu, L., Inoue, K., Hayase, T., Ohta, M.

13th International Conference on Biomedical Engineering, Vols 1-3　23　2009
Catheter and guidewire simulator for intravascular surgery (Comparison between simulation results and medical images) Peer-reviewed

Takashima, K., Ohta, M., Yoshinaka, K., Mukai, T., Oota, S.

World Congress on Medical Physics and Biomedical Engineering, Vol 25, Pt 6　25　2009
3D Observation of Expansion of Stent and Elastic Recoil using Micro-CT Peer-reviewed

Mori, Futoshi, Nakayama, Toshio, Matsuzawa, Teruo, Ohta, Makoto

World Congress on Medical Physics and Biomedical Engineering, Vol 25, Pt 6　25　2009
Methodologies to assess blood flow in cerebral aneurysms: Current state of research and perspectives Peer-reviewed

Augsburger, L., Reymond, P., Fonck, E., Kulcsar, Z., Farhat, M., Ohta, M., Stergiopulos, N., Ruefenacht, D. A.

Journal of Neuroradiology　36　(5)　270-277　2009

DOI： 10.1016/j.neurad.2009.03.001 　
Heat diffusion characteristics of magnetite nanoparticles dispersed hydro-gel in alternating magnetic field Peer-reviewed

Suto, Makoto, Kosukegawa, Hiroyuki, Maruta, Kaoru, Ohta, Makoto, Tohji, Kazuyuki, Jeyadevan, Balachandran

Journal of Magnetism and Magnetic Materials　321　(20)　3483-3487　2009

DOI： 10.1016/j.jmmm.2009.06.067 　
Anisotropic Hybrid Blood Vessel Model using Poly (Vinyl Alcohol) Hydro Gel and Mesh Material

Lei Liu, Hiroyuki Kosukegawa, Makoto Ohta, Toshiyuki Hayase

GPBE/NUS-Tohoku Graduate Student Conference in Bioengineering　19-20　2008/12
頸部内頸動脈狭窄症におけるCEAとCAS術後の医用画像を用いた患者特異的モデルと仮想モデルの流体力学シミュレーション

早瀬仁志, 中山敏男, 徳永浩司, 杉生憲志, 西田あゆみ, 有光帥二, 菱川朋人, 小野成紀, 太田信, 伊達勲

JNET: Journal of Neuroendovascular Therapy　2　(4)　297-297　2008/11
Publisher: (NPO)日本脳神経血管内治療学会
ISSN：1882-4072

eISSN：2186-2494
頸部頸動脈狭窄症 CEA vs CAS 頸動脈狭窄症に対するステント留置術と内膜剥離術治療成績、術後の頸動脈形状、血流速度およびcomputational flow dynamicsの比較検討

徳永浩司, 杉生憲志, 早瀬仁志, 有光帥二, 菱川朋人, 西田あゆみ, 小野成紀, 中山敏男, 太田信, 伊達勲

日本脳神経外科学会総会CD-ROM抄録集　67回　2E-08　2008/10
Publisher: (一社)日本脳神経外科学会
ISSN：1347-9040
Frictional characteristics of erythrocytes on coated glass plates subject to inclined centrifugal forces. International-journal Peer-reviewed

Takashi Kandori, Toshiyuki Hayase, Kousuke Inoue, Kenichi Funamoto, Takanori Takeno, Makoto Ohta, Motohiro Takeda, Atsushi Shirai

Journal of biomechanical engineering　130　(5)　051007-051007　2008/10

DOI： 10.1115/1.2948420 　

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In recent years a diamond-like carbon (DLC) film and a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer have attracted attention as coating materials for implantable artificial organs or devices. When these materials are coated on vascular devices, compatibility to blood is an important problem. The present paper focuses on friction characteristics of erythrocytes to these coating materials in a medium. With an inclined centrifuge microscope developed by the authors, observation was made for erythrocytes moving on flat glass plates with and without coating in a medium of plasma or saline under the effect of inclined centrifugal force. Friction characteristics of erythrocytes with respect to these coating materials were then measured and compared to each other to characterize DLC and MPC as coating materials. The friction characteristics of erythrocytes in plasma using the DLC-coated and noncoated glass plates are similar, changing approximately proportional to the 0.5th power of the cell velocity. The cells stick to these plates in saline as well, implying the influence of plasma protein. The results using the MPC-coated plate in plasma are similar to those of the other plates for large cell velocities, but deviate from the other results with decreased cell velocity. The results change nearly proportional to the 0.75th power of the cell velocity in the range of small velocities. The results for the MPC-coated plate in saline are similar to that in plasma but somewhat smaller, implying that the friction characteristics for the MPC-coated plate are essentially independent of plasma protein.
Measurements of Dynamic Viscoelasticity of Poly(vinyl alcohol) Hydrogel for the Development of Blood Vessel Biomodeling Peer-reviewed

Hiroyuki Kosukegawa, Keisuke Mamada, Kanju Kuroki, Lei Liu, Kosuke Inoue, Toshiyuki Hayase, Makoto Ohta

Journal of Fluid Science and Technology　3　(4)　533-543　2008/06
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jfst.3.533 　

ISSN：1880-5558

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In vitro blood vessel biomodeling with realistic mechanical properties and geometrical structures is helpful for training in surgical procedures, especial those used in endovascular treatment. Poly (vinyl alcohol) hydrogel (PVA-H), which is made of Poly (vinyl alcohol) (PVA) and water, may be useful as a material for blood vessel biomodeling due to its low surface friction resistance and good transparency. In order to simulate the mechanical properties of blood vessels, measurements of mechanical properties of PVA-H were carried out with a dynamic mechanical analyzer, and the storage modulus (G') and loss modulus (G") of PVA-H were obtained. PVA-Hs were prepared by the low-temperature crystallization method. They were made of PVA with various concentrations (C) and degrees of polymerization (DP), and made by blending two kinds of PVA having different DP or saponification values (SV). The G' and G" of PVA-H increased, as the C or DP of PVA increased, or as the proportion of PVA with higher DP or SV increased. These results indicate that it is possible to obtain PVA-H with desirable dynamic viscoelasticity. Furthermore, it is suggested that PVA-H is stable in the temperature range of 0°C to 40°C, indicating that biomodeling made of PVA-H should be available at 37°C, the physiological temperature. The dynamic viscoelasticity of PVA-H obtained was similar to that of the dog blood vessel measured in previous reports. In conclusion, PVA-H is suggested to be useful as a material of blood vessel biomodeling.
Paramater Study of Hemodynamics Simulation at Internal Carotid Stenosis Peer-reviewed

Toshio Nakayama, Hitoshi Hayase, Koji Tokunaga, Makoto Ohta

Journal of Fluid Science and Technology　3　(4)　544-552　2008/06
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jfst.3.544 　

ISSN：1880-5558

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Background and purpose: Stenting is one of the treatment options for carotid artery stenosis. To show the effectiveness of the treatment, computational fluid dynamics (CFD) has been performed for the last several decades. The inlet/outlet boundary conditions are important in CFD, and several researchers have used various inlet/outlet boundary conditions. In this paper, we compared the blood flow with various inlet/outlet boundary conditions and the measurement data obtained by an ultrasound device. Methods: Blood flow speed was measured in the internal carotid artery (ICA), the external carotid artery (ECA), and the common carotid artery (CCA) using an ultrasound device. A carotid artery was reconstructed by computed tomography (CT). Mesh in the integrated data was generated to perform flow dynamics using a commercial code. CFD for blood flow was performed using the reconstructed carotid artery. Five cases of inlet and outlet boundary conditions (I/O B.C.) were used for the CFD. The simulation results were compared with the ultrasound data on the blood flow speed in the vicinity of the center of the ICA and the ECA. Results: Various blood flow speeds were obtained from the five cases. The case of adjustment of pressures in ICA and ECA is the nearest flow speed to the ultrasound data. Conclusion: The flow speed depends on the I/O B.C.. The I/O B.C. may be necessary for the measurement data obtained by ultrasound device or magnetic resonance imaging (MRI).
Subtracted vortex centers path line method with cinematic angiography for measurement of flow speed in cerebral aneurysms. International-journal Peer-reviewed

Makoto Ohta, Naoko Fujimura, Luca Augsburger, Krisztina Barath, Hasan Yilmaz, German Abdo, Karl-Olof Lovblad, Daniel A Rüfenacht

Neurological research　30　(3)　251-5　2008/04

DOI： 10.1179/016164107X230658 　

ISSN：0161-6412

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BACKGROUND AND PURPOSE: The assessment of blood flow speed by imaging modalities is of increasing importance for endovascular treatment, such as stent implantation, of cerebral aneurysms. The subtracted vortex centers path line method (SVC method) utilizes image post-processing for determining flow quantitatively. In current practice, intra-aneurysmal flow in an in vitro model is visualized by laser sheet translumination and digitally recorded. In this study, we applied this method to cinematic angiography (CA), which is the preferred imaging method for endovascular interventions, to analyse hemodynamic changes. The SVC method was applied to the images and compared with results of the slipstream line method with colored fluid. METHODS: A transparent tubular model was constructed of silicone which included an aneurysm 10 mm in diameter and having a 5 mm neck on a straight parent artery with a diameter of 3.5 mm. The model was integrated into a pulsatile circulation system. By CA, successive images at 25 frames/s with injection of contrast were obtained. RESULTS AND CONCLUSION: Rotating vortexes of contrast, which advanced along the wall of the aneurysm, were observed in successive images of the aneurysm cavity. This phenomenon was also observed in the successive images with the slipstream line method. The speed of the vortex center was calculated and the results show that the vortex speed of CA was the same as that under the slipstream line method. This indicates the possibility of applying the SVC method to medical imaging equipment for analysis of the flow in aneurysms containing stent.
Accuracy Verification of Ultrasonic Measurement for Ultrasonic-Measurement-Integrated Simulation Using Poly (vinyl alcohol) Hydrogel Straight Tube Phantom

Lei Liu, Toshiyuki Hayase, Makoto Ohta, Kosuke Inoue

5th International Symposium on Global COE Program Global Nano-Biomedical Engineering Education and Research Network Centre　103-106　2008/03
Development of a catheter and guidewire simulator for interventional therapy Peer-reviewed

Kazuto Takashima, Shinzo Ota, Makoto Ohta, Kiyoshi Yoshinaka, Toshiharu Mukai

日本バイオレオロジー学会誌（B＆R)　22　(1)　1-7　2008/02

DOI： 10.11262/jpnbr1987.22.1_12 　
Studies on Design Optimization of Coronary Stents Peer-reviewed

Srinivas, K., Nakayama, T., Ohta, M., Obayashi, S., Yamaguchi, T.

Journal of Medical Devices-Transactions of the Asme　2　(1)　2008

DOI： 10.1115/1.2885145 　
Experimental Validation of Color Doppler Velocity Measurement for Ultrasonic-Measurement-Integrated Simulation of Blood Flow Peer-reviewed

Lei Liu, Toshiyuki Hayase, Makoto Ohta, Kosuke Inoue

Journal of Biomechanical Science and Engineering　3　(2)　161-175　2008

DOI： 10.1299/jbse.3.161 　

ISSN：1880-9863

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Cardiovascular diseases are closely related to blood flow. Ultrasonic-Measurement-Integrated (UMI) simulation, in which results of ultrasonic measurement are fed back to the flow simulation, was proposed in a previous study in order to reproduce the real blood flow accurately and efficiently. The usability of the UMI simulation was confirmed by numerical experiment, but the effectiveness of this simulation was strongly affected by the accuracy of the ultrasonic measurement. In this paper, we examined the accuracy of a commercial ultrasonic measurement device by an experiment with a PVA-H straight tube phantom. By analyzing the measured color Doppler images for a developed laminar flow inside the phantom, we obtained the relationship between the color Doppler value and the Doppler velocity (C-V relationship). It was revealed that the original C-V relationship provided in the device as a color bar was not suitable for quantitative evaluation of Doppler velocity to be used in UMI simulation. Compared with the original C-V relationship, the present C-V relationship results are in far better agreement with the analytic solution. Investigation of the normalized error confirmed that the result obtained with the present C-V relationship was reliable in cases of relatively high Reynolds number in the flow domain except near the wall. The two signal conditioning factors of the device had little influence on the Doppler velocity. Finally, we investigated the effect of temporal and spatial averaging of ultrasonic measurement data to clarify the relation between the number of averagings and the level of agreement with the analytic solution. © 2008, The Japan Society of Mechanical Engineers. All rights reserved.
Three-dimensional reconstruction of a cerebral stent using micro-CT for computational simulation Peer-reviewed

Ohta, Makoto, He, Chuan, Nakayama, Toshio, Takahashi, Akipa, Ruefenacht, Daniel A.

Journal of Intelligent Material Systems and Structures　19　(3)　313-318　2008

DOI： 10.1177/1045389X07083184 　
Reproducibility of haemodynamical simulations in a subject-specific stented aneurysm model - A report on the Virtual Intracranial Stenting Challenge 2007 Peer-reviewed

Radaellia, A. G., Augsburger, L., Cebral, J. R., Ohta, M., Ruefenacht, D. A., Balossino, R., Benndorf, G., Hose, D. R., Marzo, A., Metcalfe, R., Mortier, P., Mut, F., Reymond, P., Socci, L., Verhegghe, B., Frangi, A. F.

Journal of Biomechanics　41　(10)　2069-2081　2008

DOI： 10.1016/j.jbiomech.2008.04.035 　
Micro-Computed Tomography Intracranial Angiography in Rat Peer-reviewed

Chuan He, Makoto Ohta, Masayuki Ezura, Akira Takahashi

Proceedings of The Seventh International Symposium on Advanced Fluid Information and The Fourth International Symposium on Transdisciplinary Fluid Integration　44-46　2007/12
Parameter Study of Hemodynamics Simulation at Internal Carotid Stenosis Peer-reviewed

Toshio NAKAYAMA, Hitoshi HAYASE, Koji TOKUNAGA, Makoto Ohta

Proceedings of The Seventh International Symposium on Advanced Fluid Information and The Fourth International Symposium on Transdisciplinary Fluid Integration　3　(4)　48-49　2007/12
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jfst.3.544 　

ISSN：1880-5558

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Background and purpose: Stenting is one of the treatment options for carotid artery stenosis. To show the effectiveness of the treatment, computational fluid dynamics (CFD) has been performed for the last several decades. The inlet/outlet boundary conditions are important in CFD, and several researchers have used various inlet/outlet boundary conditions. In this paper, we compared the blood flow with various inlet/outlet boundary conditions and the measurement data obtained by an ultrasound device. Methods: Blood flow speed was measured in the internal carotid artery (ICA), the external carotid artery (ECA), and the common carotid artery (CCA) using an ultrasound device. A carotid artery was reconstructed by computed tomography (CT). Mesh in the integrated data was generated to perform flow dynamics using a commercial code. CFD for blood flow was performed using the reconstructed carotid artery. Five cases of inlet and outlet boundary conditions (I/O B.C.) were used for the CFD. The simulation results were compared with the ultrasound data on the blood flow speed in the vicinity of the center of the ICA and the ECA. Results: Various blood flow speeds were obtained from the five cases. The case of adjustment of pressures in ICA and ECA is the nearest flow speed to the ultrasound data. Conclusion: The flow speed depends on the I/O B.C.. The I/O B.C. may be necessary for the measurement data obtained by ultrasound device or magnetic resonance imaging (MRI).
Measurement of Mechanical Properties of Poly (vinyl alcohol) Hyrdogel for Development of Blood Vessel Biomodeling Peer-reviewed

Hiroyuki KOSUKEGAWA, Keisuke MAMADA, kanju KUROKI, Lei LIU, Kosuke INOUE, Toshiyuki HAYASE, Makoto Ohta

Proceedings of The Seventh International Symposium on Advanced Fluid Information and The Fourth International Symposium on Transdisciplinary Fluid Integration　50-51　2007/12
Development of Computer-Based Simulator for Catheter Navigation in Blood Vessels : 2nd Report, Evaluation of Torquability of Guidewire

TAKASHIMA Kazuto, OTA Shinzo, OHTA Makoto, YOSHINAKA Kiyoshi, MUKAI Toshiharu

Transactions of the Japan Society of Mechanical Engineers C　73　(735)　2988-2995　2007/11/25
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaic.73.2988 　

ISSN：0387-5024

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We have developed catheter simulation system in blood vessels for surgical planning and intraoperative assistance. In this study, we evaluated the torquability of the guidewire model for the simulation system. The model of the guidewire is constructed with viscoelastic springs and segments as the dynamic deformation of a flexible structure. The vessel is an elastic circular cylinder, whose shape is defined by the centerline and the radii. Collisions between the guidewire and the vessel are calculated and the contact forces are determined according to the stiffness and friction of the vessel wall. Using these models, the trajectory of the guidewire tip was calculated when the proximal part of the guidewire model was twisted at a constant speed. When the friction coefficient between the guidewire and the vessel is large, the guidewire tip vibrates. When the guidewire is twisted, there is a lag before the guidewire tip starts rotating and friction obstructs this rotation. Besides the friction coefficient, the shape of the blood vessel also affects the motion of the guidewire tip. When the guidewire becomes stiffer, the torquability of guidewire tip increases. This simulator would be useful for the analysis of the structure of the guidewire and may help guide the design of new guidewire.
ステントによる脳動脈瘤内血流の減少シミュレーション Peer-reviewed

太田信, 小助川博之, 間々田圭祐, 奥野健二郎, 黒木完樹, 中山敏男

第29回日本バイオマテリアル学会大会予稿集　55　2007/11
ネックにおけるステントデザインがおよぼす脳動脈瘤内の血行動態への影響 Invited Peer-reviewed

中山敏男, 太田信, 奥野健二郎, 高橋明, ダニエルルフナハト

第23回日本脳神経血管内治療学会総会プログラム抄録集　140　2007/11
Micro-Computed Tomography Intracranial Angiography in Rat Invited Peer-reviewed

HeChuan 太田信, 江面正幸, 高橋明

第23回日本脳神経血管内治療学会総会プログラム抄録集　224　2007/11
Dumbell aneurysm formation involving unfused BA on vertebrobasilar junction:Experience of 8cases with computational flow dynamics analysis Peer-reviewed

TsueiYuang-Seng, 松本康史, 太田信, 中山敏男, 江面正幸, 高橋明

第23回日本脳神経血管内治療学会総会プログラム抄録集　231　2007/11
Investigation of heat diffusion characterisitics of magnetic nanoparticles in AC magnetic field Invited Peer-reviewed

M.SUTO, K.MARUTA, M.OHTA, H.KOSUKEGAWA, R.J.JOSEYPHUS, K.TOHJI, B.JAYADEVAN

5th International Workshop on WATER DYNAMICS　61　2007/09
マイクロCTを用いたラットの脳血管３次元再構築 Invited Peer-reviewed

太田信, 中山敏男, 何川高橋明

日本機械学会２００７年度年次大会講演論文集　6　(No.07-1)　95-96　2007/09
Poly(vinyl alcohol)hydrogelを用いた力学的特性を付与した血管モデルの開発 Peer-reviewed

小助川博之, 間々田圭祐, 劉磊, 黒木完樹, 早瀬敏幸太田信

第36回医用高分子シンポジウム講演要旨集　81-82　2007/07
Effest of Stenting Rotational Positions on Hemodynamics in a Cerebral Aneurysm

Nakayama,T. Ohta, M. Rufenachat, D.A. Takahashi,A

AMERICAN SOCIETY OF NEURORADIOLOGY 2007: PROCEEDINGS　158　2007/06
Cinematic Angiography for Assesments of blood Flow in Cerebral Aneurysm with Stents Peer-reviewed

Ohta,M. Fujimura, N. Augsburger, L. Barath, K. Yilmaz, H Abdo,G. Ruefenachat,D.A

AMERICAN SOCIETY OF NEURORADIOLOGY 2007: PROCEEDINGS　315-316　2007/06
力学特性を付与した脳動脈瘤モデル開発のための，Poly(vinyl alcohol)hydrogelの物性評価 Invited Peer-reviewed

小助川博之, 間々田圭祐劉磊, 黒木完樹, 早瀬敏幸太田信

第30回日本バイオレオロジー学会年会　21　69　2007/06
鍼灸所見の臨床的意義と客観化六部定位の脈診について脈波情報の客観化と脈診 Invited Peer-reviewed

丸山満也, 金野敏, 仁田新一, 高島充, 白石泰之, 山家智之, 関隆志, 荒井啓行, 太田信, 劉磊, 白井敦, 早瀬敏幸

全日本鍼灸学会雑誌　57　(2)　116-118　2007/05
Publisher: The Japan Society of Acupuncture and Moxibustion
DOI： 10.3777/jjsam.57.110 　

ISSN：0285-9955

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The purpose of this symposium was to clarify clinical significance of the pulse diagnosis at the wrist used for detecting the function of various organs. Base of the literature survey and his personal experiences, the importance of reliability (reproducibility) test of the pulse diagnosis in blinded manner and necessity of clinical trials with "_??_"-specific intervention was proposed by Ogawa. A unique training program of the pulse diagnosis was introduced by Kido, and he also demonstrated a significant positive result of "_??_"-specific intervention determined by the pulse diagnosis procedure in his program and suggested the clinical significance of the pulse diagnosis. Detection of various changes in pulse waveforms at the wrist using pressure transducer was demonstrated by Maruyama, and he also suggested a possible progress of objectivity in pulse diagnosis by various sensors and biomedical devices in future. From circulatory physiological point of view, factors which may affect the pressure pulse wave at the wrist were explained with several examples of pathologic conditions by Chihara. He also suggested a possibility of reflection of general condition in the pressure pulse at the wrist although it might be partial one, and stressed the necessity of other information for the accurate diagnosis. In general discussion, it was pointed out that evidence of the pulse diagnosis was still limited, and further experimental approaches of the pulse diagnosis will be required.
交流磁場中における磁性ナノ粒子の熱拡散の数値シミュレーションおよび実験的検討 Peer-reviewed

須藤誠, 小助川博之, 丸田薫, 太田信, 田路和幸, Balachandran Jeyadevan

日本機械学会第19回「電磁力関連のダイナミクス」シンポジウム　98-100　2007/05
The Effect to Hemodynamics of an Intracranial Aneurysm by a Difference of Stent Struct Design Invited Peer-reviewed

Toshio Nakayama, Makoto Ohta, Daniel A.Rufenachat, Akira Takahashi

The 4th International Intracranial Stent Meeting　35-36　2007/04
Optimisation of Stents for Aneurysm Invited Peer-reviewed

K. Srinivas, M Ohta, T. Nakayama, S. Obayashi, T. Yamaguchi

The 4th International Intracranial Stent Meeting ICS07 PROGRAM&ABSTRACTS　38　2007/04
Studies on Funstional Biomodeling of Cerebral Artery with Mechanical Properties using Poly (vinyl alcohole) Hydro-gel Peer-reviewed

Hiroyuki KOSUKEGAWA, Keisuke MAMADA, Lei LIU, Kanju KUROKI, Toshiyuki HAYASE, Makoto OHTA

The 4th International Intracranial Stent Meeting ICS07 PROGRAM&ABSTRACTS　39-40　2007/04
脳動脈瘤内の血流に対するステントデザインの影響 Peer-reviewed

中山敏男, 太田信, Daniel A. Rufenachat, 高橋明

題46回日本生体医工学大会生体医工学　45　PS1-6-6　2007/04
傾斜遠心顕微鏡による皮膜基盤上の赤血球の摩擦特性計測 Peer-reviewed

神取孝司, 井上浩介, 早瀬敏幸, 高木敏行, 竹野貴法, 太田信, 武田元博

日本機械学会東北支部第42期総会・講演会　111-112　2007/03
シネマティックアンギオグラフィにオプティカルフロー法を適用した血流の定量測定法開発 Peer-reviewed

恩田一寿, 太田信

日本機械学会東北支部第42期総会・講演会　115-116　2007/03
脈診の数値モデル構築のための基礎的研究 Peer-reviewed

鳴海賢太郎, 中西勉, 劉磊, 白井敦, 早瀬敏幸, 太田信, 金野敏, 川田浩, 丸山満也, 仁田新一

日本機械学会東北支部第42期総会・講演会　121-122　2007/03
In-vitro model of artery based on Poly vinyl alcohol (PVA) hydrogel (PVA-H) with low friction Invited Peer-reviewed

Makoto Ohta

The 4th LYON-TOHOKU ENGINEERING & SCIENCE FORUM　23　2007/02
Bio-tribology of a catheter/biomodel vessel contact Invited

Makoto Ohta

The 4th LYON-TOHOKU ENGINEERING & SCIENCE FORUM　71　2007/02
The Effect of Stenting with Difference Positions on Hemodynamics in a Cerebral Aneurysm Peer-reviewed

Toshio Nakayama, Makoto Ohta, Daniel A.Rufenachat, Akira Takahashi

The 9th International Symposium on Future Medical Engineering Based on Bio-nanotechnology　106-107　2007/01
実形状ステントを設置した脳動脈瘤内の血流シミュレーション Peer-reviewed

中山敏男, 太田信, 信 Daniel A.Rufenachat, 高橋明

第19回バイオエンジニアリング講演会講演論文集　84-85　2007/01
Cinematic angiography for measurements of blood flow in cerebral aneurysms with stents Peer-reviewed

Ohta, Makoto, Fujimura, Naoko, Augsburger, Luca, Yilmaz, Hasan, Rufenacht, Daniel A., ASME

Fedsm 2007: Proceedings of the 5th Joint Asme/jsme Fluids Engineering Summer Conference, Vol 2, Pts a and B　FEDSM2007-37254　(CD-ROM)　1-6　2007

DOI： 10.1115/FEDSM2007-37254 　
Micro-Computed Tomography Selective Intracranial Vascular Angiography in Rat

He, C, Ohta, M, Nakayama, T, Takahashi, A

The 2nd Tohoku-NUS Joint Symposium on the Future Nano-medicine and Bioengineering in the East Asian Region　91-92　2006/12
Application of Ultrasonic Measurement to PVA-H Tissue-mimicking phantom

Liu L, Inoue, K, Hayase, T, Ohta, M

The 2nd Tohoku-NUS Joint Symposium on the Future Nano-medicine and Bioengineering in the East Asian Region　97-98　2006/12
Fundamental Study ofUltrasonic-Mesurement-Integrated Simulation: Numerical Experimant and Experimantal Applicatin with PVA Straight Pipe Model Peer-reviewed

Lei LIU, Kosuke INOUE, Toshiyuki HAYASE, Makoto OHTA

Proceedings of the 6th International Symposium on Advanced Fluid Information,　53-54　2006/12
血管内カテーテルシミュレータに関する基礎研究(第2報，接触力算出方法の評価)

高嶋一登, 大田慎三, 太田信, 葭仲潔, 向井利春

第17回バイオフロンティア講演会講演論文集　6　(46)　49-50　2006/11
脈診における脈派情報の取得に関する数学モデルの構築と実験による検証

鳴海賢太郎, 中西勉, 劉磊, 井上浩介, 白井敦, 早瀬敏幸, 太田信, 金野敏, 川田浩, 丸山満也, 白石泰之, 仁田新一

第17回バイオフロンティア講演会講演論文集　6　(46)　55-56　2006/11
ステントの3次元形状データを用いた動脈瘤内の血流シミュレーション

中山敏男, 太田信, Rüfenacht, DA, 高橋明

第22回日本脳神経血管内治療学会総会　157　2006/11
3次元PIVデータによる脳内速度分布の定量的解析

村上洋紀, 太田信, 早瀬敏幸, 加藤琢真, 小杉隆司, 礒田治夫

第22回に本能神経血管内治療学会　157　2006/11
Numerical Simulation of Hemodynamics in Cerebral Arterial Aneurysm using Realistic Stent Data Peer-reviewed

Nakayama, T, Ohta, M, Rüfenacht, DA, Takahashi, A

the 6th International Symposium on Advanced Fluid Information　47-48　2006/10
脳動脈瘤の3次元形状計測分析

太田信, Rüfenacht DA

流体工学部門講演会講演概要集　06　(21)　110　2006/10
3-D Reconstruction of a Cerebral Stent Using micro-CT for Computational Simulation Peer-reviewed

Ohta, M, He C, Nakayama, T, Takahashi, A, Rüfenacht DA

International Joing Conference of INABIO/SMEBA 2006　97　2006/09
Three dimensional measurements of cerebral Aneurysms and vessel size Peer-reviewed

Ohta, M, Lachenal. Y, Augsburger, G, Abdo, G, Yilmaz, H, Fujimura, N, Babic, D, Lylyk, P, Rüfenacht, DA

Journal of Biomechanics　39S1　S364　2006/08
カテーテルシミュレータの開発 Peer-reviewed

高嶋一登, 大田慎三, 太田信, 葭仲潔, 池内健

日本機械学会論文集　72　(719)　2006/07

DOI： 10.1299/kikaic.72.2137 　
Three Diamensions Image of Cerebral Vascular for computational Fluid Dynamics in rat: feasibility of assessment with Micro-CT Peer-reviewed

He, C, Nakayama, T, Ohta, M, Takahashi, A

the Third International Symposium on Transdisciplinary Fluid Integration　59-60　2006/06
Evaluation of 4D-CT by contrast comparison way with Scion image

Fujimaro Ishida, Yasuyuki Umeda Yusuke Kamei, Masahiko Okada, Makoto Ohta, Hidenori Suzuki Waro Taki

The 35th annual meeting of the japanese Society of Neuroradiology　122　2006/02
Fundamental study on catheter simulator for intravascular surgery Invited

Kazuto Takashima, Shinzo Ota, Makoto Ohta, Yoshinaka Ken Ikeuchi

Proceedings of the 18th Bioengineering Conference, 2005 Annual meeting of BE D/JSME　05-66　355-356　2006/01/12
Three dimensional imaging of cerebral vasculature for computer fluid dynamics in rat: Feasibility of assessment with micro-CT Peer-reviewed

He, Chuan, Takahashi, Akira, Nakayama, Toshio, Ohta, Makoto

Future Medical Engineering Based on Bionanotechnology, Proceedings　2006

DOI： 10.1142/9781860948800_0099 　
Numerical realization of blood flow in aneurysmal aorta by integrating measurement and simulation Peer-reviewed

Hayase, Toshiyuki, Funamoto, Kenichi, Yamagata, Takayuki, Liu, Lei, Shirai, Atsushi, Ohta, Makoto, Inoue, Kosuke, Saijo, Yoshifumi, Yambe, Tomoyuki

Future Medical Engineering Based on Bionanotechnology, Proceedings　2006

DOI： 10.1142/9781860948800_0092 　
Experimental validation of Ultrasonic-Measurement-Integrated Simulation for blood flow in aorta Peer-reviewed

Liu, Lei, Inoue, Kosuke, Hayase, Toshiyuki, Ohta, Makoto

Future Medical Engineering Based on Bionanotechnology, Proceedings　2006

DOI： 10.1142/9781860948800_0105 　
Scion Imageをもちいたコントラスト比較法による4D-CT movieの評価

Fujimaro Ishida, Yasuyuki Umeda Yusuke Kamei Yasuhiko Okada Makoto Ohta Hidenori Suzuki Waro Taki

第35回日本神経放射線学会　122　2006
血管内カテーテルシミュレータに関する基礎研究

高嶋一登, 大田慎三, 太田信, 信, 葭仲, 潔, 池内健

第18 回バイオエンジニアリング講演会講演論文集　05-66　355-356　2006/01
Numerical analysis of the flow pattern in stented aneurysms and its relation to velocity reduction and stent efficiency Peer-reviewed

Hirabayashi, Miki, Ohta, Makoto, Barath, Krisztina, Ruefenacht, Daniel A., Chopard, Bastien

Mathematics and Computers in Simulation　72　(2-6)　128-133　2006

DOI： 10.1016/j.matcom.2006.05.037 　
Method to quantify flow reduction in aneurysmal cavities of lateral wall aneurysms produced by stent implants used for flow diversion Peer-reviewed

Fujimura, N, Ohta, M, Abdo, G, Ylmaz, H, Lovblad, KO, Rufenacht, DA

Interventional Neuroradiology　12　(S1)　197　2006

DOI： 10.1177/15910199060120S135 　
Development of fundamental technologies with use of in-vitro and in-silico models for endovascular treatments Invited Peer-reviewed

Daniel A. Rüfenacht, Pedro Lylyk, Toshiyuki Hayase

Proceedings of the fifth international symposium on advanced fluid information - IFS-JAXA joint symoposium-　32-33　2005/12/08
Development of a functional vessel biomodelling with Poly (vinyl alcohol) Hydrogel for in-vitro simulation Peer-reviewed

Lei Liu, Kousuke Inoue, Toshiyuki Hayase, Akira Handa, Edouard Fonck, Fumio Asakura, Stephan G. Wetzel, German Abdo, Hasan Yilmaz, Karl-Olof. Lovblad, Luca Augsburger, Daniel A. Rüfenacht, Hiroo Iwata, Suong-Hyu Hyon, Sadami Tsutsumi

The 6th international symposium on future medical engineering based on Bio-nanotechnology (21st Century COE program)　31-32　2005/11/21
Development of measurement of blood flow in cerebral aneurysm with use of cinematic angiography (second edition) Peer-reviewed

Naoko Fujimura Luca Augsburger Edouard Fonck Hasan Yilmaz German Abdo Barath, Krisztina Karl Olof-lovbrad, Daniel Ruefenacht

The 21st annual meeting of the Japanese society for neuroendovascular therapy　132　2005/11
Development of cerebral aneurysm biomodelling of tubular model made of PVA Peer-reviewed

Naoko Fujimura Luca Augsburger Edouard Fonck Daniel Ruefenacht, Akira Takahashi, Hiroo Iwata, Sadami Tsutsumi

The 21st annual meeting of the Japanese society for neuroendovascular therapy　216　2005/11
Impact of stent on blood flow in a model of cerebral aneurysm

Naoko Fujimura, Luca, Augsburger, Stephan Wetzel, Hasan Yimaz, German Abdo, Karl-Olof Lobvled, Krisztina Barath, Daniel, A. Ruefenacht

Proceedings of 2005 annual meeting, Japan society of fluid mechanics　224-224　2005/09
Development of Flow speed in cerebral aneurysm by using cinematic angiography Peer-reviewed

Naoko Fujimura, Hiroo Iwata, Sadami Tsutsumi, Daniel A. Ruefenacht

Mechanical Engineering Congress, 2005, Japan　5　87-88　2005/09
Numerical simulations of flow changes induced by insertion of flow diverter in idealized models of cerebral aneurysms: a parametrical study Invited Peer-reviewed

L. Augsburger, E Fonck, M Ohta, DA Rufenacht, N Stergiopulos

swiss society for biomedical engineering　F02-F02　2005/09/01
Development of In-vitro model of cerebral aneurysm by PVA

Makoto Ohta Lei Liu Toshiyuki, Hayase Akira, Handa DA Ruefenacht, Hiroo Iwata, Sadami Tsutsumi

Journal of Japanese Society od Biorheology　28　(s)　36-36　2005/06/30
Transdisciplinary Methodology Integrating Measurement and Simulation in Application of Complex Biomedical Flows

Toshiyuki Hayase, Kenichi Funamoto, Takayuki Yamagata, Lei Liu, Atsushi Shirai, Makoto Ohta, Kosuke Inoue, Yoshifumi Saijo, Tomoyuki Yambe

Proceedings of the 5th International Symposium on Advanced Fluid information (AFI-2005)　36-39　2005
Measurement of elastic properties of blood vessels Peer-reviewed

D. Ilic, T. Moix, O. Lambercy, L. Sache, H. Bleuler, M. Ohta, L. Augsburger

2005 27th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, Vols 1-7　0-7803-8740　6199-6202　2005
Publisher: IEEE
ISSN：1094-687X

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This paper is related to the measurements of the modulus of elasticity of an artery by studying the deformations due to the inflation of an angioplasty balloon catheter used for Interventional Radiology (IR) procedures. Various types of balloons are studied in order to characterize and compare their behaviors at the time of inflation. A test bench, consisting of an angioplasty balloon, a Polyvinyl alcohol model and an actuator used to inflate a balloon, is developed for the realization of the experiments. The pressure-volume curve during the inflation of a balloon is observed. Elasticity modulus are derived with an analytical model of the measurement system. The results are then analyzed and compared to existing data from literature.
Measurement of internal constraints during.an interventional radiology procedure Peer-reviewed

D. Ilic, I. Moix, O. Lambercy, L. Sache, H. Bleuler, M. Ohta, L. Augsburger

2005 27TH ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY, VOLS 1-7　0-7803-8740　2615-2618　2005
Publisher: IEEE
ISSN：1094-687X

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This paper presents a novel method for measurements of internal constraints during an Interventional Radiology procedure. Fiber-optic strain gauge, operating as a Fabry-Perot interferometer, is inserted and navigated inside a polyvinyl alcohol (PVA) model. The information obtained from deformation of the Fabry-Perot cavity is analyzed and the results are then rescaled through a calibration procedure for catheters. The measures help to locate the maximum interaction forces between catheter and blood vessel wall at approximately 1.3 N and to observe the shape of dynamic interaction during manipulation.
From patient to model: Stereolithographic modeling of the cerebral vasculature based on rotational angiography Peer-reviewed

Wetzel, SG, Ohta, M, Handa, A, Auer, JM, Lylyk, P, Lovblad, KO, Babic, D, Rufenacht, DA

American Journal of Neuroradiology　26　(6)　1425-1427　2005
Influence of stent properties on the alteration of cerebral intra-aneurysmal haemodynamics: flow quantification in elastic sidewall aneurysm models. International-journal Peer-reviewed

Krisztina Baráth, Francis Cassot, Jean H D Fasel, Makoto Ohta, Daniel A Rüfenacht

Neurological research　27 Suppl 1　(1)　S120-8-128　2005

DOI： 10.1179/016164105X35477 　

ISSN：0161-6412

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OBJECTIVES: Stent implantation across the neck of cerebral aneurysms may induce intra-aneurysmal flow reduction, and consequently saccular thrombosis and vessel wall repair. To analyse the influence of different stent parameters on such flow reduction, we studied the flow changes in vascular models, induced by a series of stents. METHODS: Two different neck-sized elastic sidewall aneurysm models were connected to a circulatory loop. Twenty different stents were introduced in both models to analyse the effect of their parameters, such as porosity, filament diameter and permeability. Flow patterns were visualized by using glass particles and laser sheet translumination. The digitally recorded data were transferred for computer analysis. The changes of the vortex velocity for each stent model combination were investigated and statistically evaluated. RESULTS: Intra-aneurysmal flow analysis showed dispersion of the vortices of a variable degree, and velocity reduction of 30% mean in model 1 and 49% mean in model 2. By statistical analysis three groups of stents ('best', 'medium', 'worst') were identified, according to their haemodynamic efficacy. No correlations were observed between the haemodynamic performance of the stents and the porosity, filament diameter and permeability values separately. The stent effects were on average more important in the large-necked than in the small-necked aneurysm model. DISCUSSION: Stent implantation induces intra-aneurysmal loss of vortex coherence and flow reduction. The analysed stent parameters show complex interrelationship, including also stent 'design'. The difference in the haemodynamic efficacy of the individual stents between the two models raises the question of 'stent positioning effects'.
Rheological changes after stenting of a cerebral aneurysm: A finite element modeling approach Peer-reviewed

Ohta, M, Wetzel, SG, Dantan, P, Bachelet, C, Lovblad, KO, Yilmaz, H, Flaud, P, Rufenacht, DA

Cardiovascular and Interventional Radiology　28　(6)　768-772　2005

DOI： 10.1007/s00270-004-7148-6 　
Development of a polyvinyl alcohol hydrogel for temperature measurement by MRI. International-journal Peer-reviewed

Makoto Ohta, J Paul Jacobson, Emile Hiltbrand, Alexis Kelekis, Marko Ivancevic, Daniel A Rüfenacht, Hiroo Iwata, Sadami Tsutsumi

Technology and health care : official journal of the European Society for Engineering and Medicine　13　(4)　221-8　2005

ISSN：0928-7329

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This paper describes the development of a Polyvinyl alcohol hydrogel (PVA-H) model for calibration and measurement of temperature using image contrast on MRI using DMSO/H_2O as a solvent to alter the freezing and melting points of PVA-H. Tissues exposed to temperature changes above 41 degrees C or below 0 degrees C exhibit increasingly extensive and irreversible damage, depending on the exposure duration. MR images can provide a map of temperature if there is sufficient tissue signal. To evaluate treatment principles using temperature changes (hyperthermia, cryotherapy), a model simulating tissue may be useful to provide a reproducible test environment. PVA-H is water soluble and can be seen on MRI. It can be used to construct complicated shapes such as vascular structure, soft tissues, and so on. Therefore, PVA-H can be useful to measure temperatures and assume the distribution of temperature under treatment. In this paper, we applied PVA-H as a temperature detector and calibrated temperature from image contrast. The results exhibit good capability as a temperature detector not only of high temperature (around 41 degrees C), but also of low temperature (as low as -23 degrees C).
Current Concept of Endovascular Aneurysm Treatment and about the Role of Stents for Endovascular Repair of Cerebral Arteries Peer-reviewed

Daniel A. Rüfenacht, Makoto Ohta, Hasan Yilmaz, Carlos Miranda, Diego San Millan Ruiz, German Abdo, Pedro Lylyk

Swiss Archives of Neurology and Psychiatry　155　(7)　348-352　2004/07
Impact of stent design on intra-aneurysmal flow - A computer simulation study Peer-reviewed

Ohta, M, Hirabayashi, M, Wetzel, S, Lylyk, P, Wata, H, Tsutsumi, S, Rufenacht, DA

Interventional Neuroradiology　10　(Supp2)　85-94　2004

DOI： 10.1177/15910199040100S216 　
A lattice Boltzmann study of blood flow in stented aneurism Peer-reviewed

Hirabayashi, M, Ohta, M, Rufenacht, DA, Chopard, B

Future Generation Computer Systems　20　(6)　925-934　2004

DOI： 10.1016/j.future.2003.12.004 　
Poly-vinyl alcohol hydrogel vascular models for in vitro aneurysm simulations: the key to low friction surfaces. International-journal Peer-reviewed

Makoto Ohta, Akira Handa, Hiroo Iwata, Daniel A Rüfenacht, Sadami Tsutsumi

Technology and health care : official journal of the European Society for Engineering and Medicine　12　(3)　225-33　2004

ISSN：0928-7329

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PURPOSE: To develop a vessel model with poly-vinyl alcohol hydrogel (PVA-H) with low surface friction for in vitro simulations of vascular pathologies. MATERIALS AND METHODS: Simulations of variable vascular pathologies were based on human vessel casts reproduced in wax. Constructions of vascular models were then obtained by lost wax techniques. As materials, liquid silicon or PVA in organic solvents were used. After solidification, the wax was drained by heating. Comparison of PVA-H with silicone models included evaluation of surface characteristics (friction coefficient), of visibility (transparence and compatibility with medical imaging techniques), and of stiffness (pulsatility of vascular lumen). Both model types were integrated in a circulation circuit allowing for flow simulations and testing with endovascular medical devices. RESULTS AND CONCLUSION: Both model types were transparent and compatible with current medical imaging methods. PVA-H models exhibited much lower friction characteristics. PVA-H stiffness was closer to soft tissue when compared to silicone, allowing for pulsations during flow simulations.
Characterization of flow reduction properties in an aneurysm due to a stent. International-journal Peer-reviewed

Miki Hirabayashi, Makoto Ohta, Daniel A Rüfenacht, Bastien Chopard

Physical review. E, Statistical, nonlinear, and soft matter physics　68　(2 Pt 1)　021918-021918　2003/08

DOI： 10.1103/PhysRevE.68.021918 　

ISSN：1539-3755

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We consider a lattice Boltzmann simulation of blood flow in a vessel deformed by the presence of an aneurysm. Modern clinical treatments involve introducing a stent (a tubular mesh of wires) into the cerebral artery in order to reduce the flow inside the aneurysm and favor its spontaneous reabsorption. A crucial question is to design the stent with suitable porosity so as to produce the most effective flow reduction. We propose a stent positioning factor as a characterizing tool for stent pore design in order to describe the flow reduction effect and reveal the several flow reduction mechanisms using this effect.
Lattice Boltzmann analysis of the flow reduction mechanism in stented cerebral aneurysms for the endovascular treatment Peer-reviewed

Hirabayashi, M, Ohta, M, Rufenacht, DA, Chopard, B

Computational Science - Iccs 2003, Pt I, Proceedings　2657　2003
Publisher: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Control of crystalline orientation to enhance the wear resistance of ultra-high molecular weight polyethylene crystallization cups for artificial joints Peer-reviewed

Ohta, M, Hyon, SH, Tsutumi, S

Wear　255　(7-12)　1045-1050　2003

DOI： 10.1016/S0043-1648(03)00284-9 　
Wear properties of UHMWPE oriented under uniaxial compression during the molten state and at lower temperatures than the melting point Peer-reviewed

Ohta, M, Hyon, SH, Kang, YB, Oka, M, Tsutsumi, S, Murakami, S, Kohjiya, S

Jsme International Journal Series C-Mechanical Systems Machine Elements and Manufacturing　46　(4)　1297-1303　2003

DOI： 10.1299/jsmec.46.1297 　
Shear Modulus and Viscosity Measurement Using MR Elastography

OSHIRO Osamu, SUGA Mikio, OHTA Makoto, MATSUDA Tetsuya, TSUTSUMI Sadami, MINATO Kotaro, CHIHARA Kunihiro, TAKAHASHI Takashi

Medical Imaging Technology　19　(5)　389-399　2001/09/25
Publisher: The Japanese Society of Medical Imaging Technology
DOI： 10.11409/mit.19.389 　

ISSN：0288-450X
Surface Modification of Manesium by NaHCO_3 and Corrosion Behavior in Hank's solution for New Biomaterial Applications

AL-ABDULLAT Yousef, TSUTSUMI Sadami, NAKAJIMA Naoki, OHTA Makoto, KUWAHARA Hideyuki, IKEUCHI Ken

MATERIALS TRANSACTIONS　42　(8)　1777-1780　2001/08/20
Publisher: The Japan Institute of Metals and Materials
DOI： 10.2320/matertrans.42.1777 　

ISSN：1345-9678

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The present study was carried out to improve the corrosion resistance of pure magnesium in Hank’s Balanced Salt Solution (HBSS) through the surface modification. Three kinds of alkaline compounds, such as sodium hydrogen carbonate, sodium carbonate, and lithium hydroxide, were used for treatment. Only magnesium treated with aqueous sodium hydrogen carbonate solution gave a good corrosion resistance in HBSS solution at 25°C up to 75 days, while almost no effect in sodium carbonate and lithium hydroxide. It was likely that hydrogen carbonate ions were essential for the surface improvement of magnesium. X-ray diffraction patterns of modified magnesium showed new peaks of magnesium carbonate and others on the surface. New surface structure of needle-shaped crystals was observed by scanning electron microscopy (SEM). Both elemental mapping, and energy dispersive (EDX) techniques in SEM showed the precipitation of calcium magnesium phosphate (low crystallinity whitlockite:(Ca,Mg)3(PO4)2) on the surface of magnesium specimen. It could be concluded that surface modification with sodium hydrogen carbonate made it possible to apply metal magnesium in biomedical, dental, and other industrial usage.
Risk factors and predictors of coronary arterial lesions in Japanese hypertensive patients

Kato, J., Aihara, A., Kikuya, M., Matsubara, M., Ohta, M., Ohkubo, T., Tsuji, I., Sekino, H., Meguro, T., Imai, Y.

Hypertension Research　24　(1)　3-11　2001
Publisher: The Japanese Society of Hypertension
DOI： 10.1291/hypres.24.3 　

ISSN：0916-9636

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The morbidity rate of coronary artery disease has recently increased in Japan. This is attributable to changes from traditional to more westernized lifestyles. In this study, we therefore examined the risk factors and predictors of coronary arterial lesions in Japanese patients with essential hypertension. Coronary angiography was performed in 109 consecutive essential hypertension patients (57 men and 52 women; 66±8.0 years of age) with either angina pectoris or atypical chest pain, who were chosen from 485 consecutive hypertensive patients in a hypertension clinic in Sendai, Japan. Coronary arterial stenosis of greater than 50% was defined as significant and used as a dependent variable for the multiple regression analysis. Risk factors were defined as factors confirmed to have a causal relationship with coronary arterial lesions, whereas arteriosclerotic complications and hypertensive target organ damage were defined as predictors. Multiple logistic regression analysis was performed using these parameters as independent variables. Of 109 patients, 25 had a coronary arterial stenosis greater than 50%. A smoking habit (odds ratio (OR): 4.48; 95% confidence interval (CI): 1.13-17.82; p<0.05), hypercholesterolemia (OR: 5.34; 95% Cl: 1.52-18.73; p<0.05), and 24-h diastolic blood pressure (OR: 2.33; 95% Cl: 1.06-5.16; p<0.05) were significant risk factors, whereas carotid intima-media thickness (OR: 5.85; 95% Cl: 1.48-23.2; p<0.05) was a significant predictor of coronary arterial lesion. When two of the major risk factors (a smoking habit, hypercholesterolemia, or impaired glucose tolerance including diabetes mellitus) were clustered in addition to the hypertension, the risk of coronary arterial lesions increased by 6.7 to 10.1 times. These findings indicate that the major risk factors established in Caucasians, I.e., a smoking habit, hypercholesterolemia and blood pressure level, are also risk factors for coronary arterial lesions in Japanese with essential hypertension. The presence of two or more risk factors increases the risk of coronary arterial lesions synergistically in the presence of hypertension. (Hypertens Res 2001; 24: 3-11)
Residual Stress Measurements of Ultra-high Molecular Weight Polyethylene for Artificial Joints Peer-reviewed

Makoto Ohta, Sadami Tsutumi, Suong-Hyu Hyon, Yu-Bong Kang, Hirotaka Tanabe, Yoshio Miyoshi

Russian j. Biomechanics　5　(2)　30-38　2001
Effect of the compression ratio on wear properties of slightly cross-linked ultra-high molecular weight polyethylene, crystallized under uniaxial compression Peer-reviewed

Ohta, M, Hyon, SH, Kang, YB, Murakami, S, Kohjiya, S, Oka, M, Tsutsumi, S

Wear　250　(1-12)　145-151　2001

DOI： 10.1016/S0043-1648(01)00606-8 　
Wear Properties and Mechanical Properties of Slightly Cross-Linked Ultra-High Molecular Weight Polyethylene Crystallized under Uniaxial Compression

OHTA Makoto, HYON Suong-Hyu, KANG Yu-Bong, OKA MASANORI, TSUTSUMI Sadami, MURAKAMI Syozo, KOHJIYA Shinzo

Journal of the Society of Materials Science, Japan　49　(12)　1301-1305　2000/12/15
Publisher: The Society of Materials Science, Japan
DOI： 10.2472/jsms.49.1301 　

ISSN：0514-5163

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In order to improve the wear properties of artificial joints, a slightly cross-linked ultra high molecular weight polyethylene (UHMWPE) was compressed at molten state and crystallized by cooling to room temperature. The molecular chain of the UHMWPE was orientated to the direction of deformation. Density and melting point of the mold article were increased in accordance with compression ratio. The αc peak of loss modulus was shifted to higher temperature compared with the non-compressed sample. And it was also revealed that the weight loss of the compressed UHMWPE was remarkably less than that of a non-compressed sample from the result of the pin-on-disc wear test.
【Sensible Human Project】局所生体弾性率のMR Elastography法を用いた計測と評価 Peer-reviewed

菅幹生, 湊小太郎, 松田哲也, 大城理, 千原國宏, 太田信, 堤定美, 小森優, 高橋隆, 岡本淳, 滝沢修

MEDICAL IMAGING TECHNOLOGY　18　(6)　769-776　2000/11
Publisher: 日本医用画像工学会
ISSN：0288-450X

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MR Elastography(MRE)法を用いることで弾性体内部を伝わる弾性波を画像化できる.弾性率は外部震動周波数,弾性体の密度及び弾性波の波長から計算できるため,MRE画像から局所波長を求めることで生体内の剛性率の分布を非侵襲的に測定できる.MRE画像から弾性率の局所分布を得るために,MRI装置内で駆動可能な加震システムと撮影シーケンスを開発し,初期位相の異なる複数のMRE画像を用いた局所波長計測手法を考案した.本システムの信頼性を検証するために,硬さの異なる複数の弾性体試料について物理的計測値との比較を行い,両者の結果がよく一致することを確認した.又,本手法を用いて,実際に生体組織の弾性係数を計測可能であることを示した
Measurement and Evaluation of Loval Tissues Elastic Modulus

SUGA Mikio, MINATO Kotaro, MATSUDA Tetsuya, OSHIRO Osamu, CHIHARA Kunihiro, OHTA Makoto, TSUTSUMI Sadami, KOMORI Masaru, TAKAHASHI Takashi, OKAMOTO Jun, TAKIZAWA Osamu

Medical Imaging Technology　18　(6)　769-776　2000/11/01
Publisher: The Japanese Society of Medical Imaging Technology
DOI： 10.11409/mit.18.769 　

ISSN：0288-450X
Residual stress measurements of lightly cross-linked UHMWPE crystallized under uniaxial compression for artificial joints

OHTA Makoto

Journal of Japanese Society for Clinical Biomechanics and Related Research　21　319-322　2000/10/01

ISSN：1340-9018
Analysis of Mandible with Turbo-FLASH MR Imaginng System Invited Peer-reviewed

Takashi Azuma, Toshiyuki Nambu, Kenji Doi, Makoto Ohta, Sadami Tsutsumi, Hiroshi Inoue, Kouji Hayashi, Jin Ito, Toshihiro Mata, Manabu Kutsuki

Journal of Japanese Society for Clinical Biomechanics and Related Research　21　489-495　2000
Surface reaction of magnesium in Hank's solutions Peer-reviewed

Kuwahara, H, Al-Abdullat, Y, Ohta, M, Tsutsumi, S, Ikeuchi, K, Mazaki, N, Aizawa, T

Magnesium Alloys 2000　350-3　349-358　2000

DOI： 10.4028/www.scientific.net/MSF.350-351.349 　
Wear Resistant Properties and Mechanical Properties of UHMWPE : Crystallized under the Compression

HYON Suong-Hyu

Journal of Japanese Society for Clinical Biomechanics and Related Research　20　293-296　1999/10/01

ISSN：1340-9018
Methods to reduce the wear of ultrahigh-molecular-weight polyethylene Peer-reviewed

Oka, M, Hyon, SH, Ohta, M, Nakamura, T, Ushio, Y, Toguchida, J

Joint Arthroplasty　1999
Dynamic modulus measurements of a lightly cross-linked ultra-high molecular weight polyethylene crystallized under uniaxial compression Peer-reviewed

Makoto Ohta, Suong-Hyu Hyon, Yu-Bong Kang, Sadami Tsutsumi, Masanori Oka, Syozo Murakami, Shinzo Kohjiya

Russian Journal of Biomechanics　3　(4)　34-48　1999
Wear resistance of lightly cross-linked ultrahigh-molecular-weight polyethylene crystallized from the melt under uniaxial compression Peer-reviewed

Ohta, M, Hyon, SH, Oka, M, Tsutsumi, S

Wear　225　(1-2)　312-318　1999

DOI： 10.1016/S0043-1648(99)00077-0 　
Studies on Vibration Characteristics of Dental Implants Invited Peer-reviewed

Makoto Ohta, Kohei Murase, Tomoe Ito, Sadami Tsutsumi

Journal of Japanese Society for Clinical Biomechanics and Related Research　19　303-306　1998
Wear Resistant Properties of UHMWPE Crystallized under the Compression Peer-reviewed

Suong-Hyu Hyon, Makoto Ohta, Sadami Tsutsumi, Ken Ikeuchi, Masanori Oka

Journal of Japanese Society for Clinical Biomechanics and Related Research　19　461-465　1998

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Misc. 197

A Review of Functional Analysis of Endothelial Cells in Flow Chambers

Makoto Ohta, Naoya Sakamoto, Kenichi Funamoto, Zi Wang, Yukiko Kojima, Hitomi Anzai

JOURNAL OF FUNCTIONAL BIOMATERIALS　13　(3)　2022/09
Publisher: MDPI
DOI： 10.3390/jfb13030092 　

eISSN：2079-4983

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The vascular endothelial cells constitute the innermost layer. The cells are exposed to mechanical stress by the flow, causing them to express their functions. To elucidate the functions, methods involving seeding endothelial cells as a layer in a chamber were studied. The chambers are known as parallel plate, T-chamber, step, cone plate, and stretch. The stimulated functions or signals from endothelial cells by flows are extensively connected to other outer layers of arteries or organs. The coculture layer was developed in a chamber to investigate the interaction between smooth muscle cells in the middle layer of the blood vessel wall in vascular physiology and pathology. Additionally, the microfabrication technology used to create a chamber for a microfluidic device involves both mechanical and chemical stimulation of cells to show their dynamics in in vivo microenvironments. The purpose of this study is to summarize the blood flow (flow inducing) for the functions connecting to endothelial cells and blood vessels, and to find directions for future chamber and device developments for further understanding and application of vascular functions. The relationship between chamber design flow, cell layers, and microfluidics was studied.
コイル塞栓術における脳血管内治療医の注視点の特徴と経験症例数との関係

岡本吉弘, 庄島正明, 新妻邦泰, 太田信, 植松美幸, 迫田秀行, 配島由二

人工臓器(日本人工臓器学会)　49　(2)　2020

ISSN：0300-0818
Cerebrovascular Model Equipped with Microsensors

芳賀洋一, 芳賀洋一, 吉田洋, 松永忠雄, 清水康智, 太田信, 太田信, 庄島正明, 益田泰輔, Yu Kaihong, Simon Tupin, Dai Chenming, 新井史人, 原田香奈子

電気学会論文誌 E　140　(12)　2020

ISSN：1341-8939
Development of Device Placement Simulator for Endovascular Treatment (Evaluation of Coil Contact Force and Catheter Motion)

大石卓弥, 高嶋一登, 葭中潔, YU Kaihong, 太田信, 森浩二, 当麻直樹

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　31st　2020

ISSN：1348-2939
Behavior of flow in a middle cerebral aneurysm with deformation

池谷直紀, 山崎智皓, 田中学, 太田信, 山口隆平

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　31st　2020

ISSN：1348-2939
Numerical simulation of flow behavior in basilar bifurcation artery aneurysms based on 4D-CTA

山崎智皓, 岡崎陽大, 田中学, 太田信, 石田藤麿, 山口隆平

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　31st　2020

ISSN：1348-2939
6th International Conference on Computational and Mathematical Biomedical Engineering（CMBE2019）を開催して

太田信

日本バイオレオロジー学会会報　33　(3)　124-124　2019
Publisher: 特定非営利活動法人日本バイオレオロジー学会
DOI： 10.11262/jpnbr.33.3_124 　

ISSN：0913-4778

eISSN：2186-5663
Behavior of flow in patient-specific cerebral aneurysm with wall elasticity

滝澤岳, 田中学, TUPIN Simon, 太田信, 山口隆平

バイオエンジニアリング講演会講演論文集(CD-ROM)　32nd　2019

ISSN：2424-2829
脳動脈瘤コイル留置のシミュレーション-手法と応用例-

高嶋一登, 当麻直樹, 太田信, 森浩二

脳血管内治療(Web)　4　(Supplement)　2019

ISSN：2424-1709
脳動脈瘤コイル留置のシミュレーション-目的と課題-

当麻直樹, 高嶋一登, 太田信, 森浩二

脳血管内治療(Web)　4　(Supplement)　2019

ISSN：2424-1709
Normalization of Basilar Artery Structure with MRA Images

北村洸, 麦倉俊司, 太田信, 安西眸

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　30th　2019

ISSN：1348-2939
PARTICLE IMAGE VELOCIMETRY ANALYSIS OF FLUSH FLOW DURING INTRAVASCULAR ENDOSCOPY

三塚康平, TUPIN Simon, LI Yujie, 中山敏男, 太田信

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　30th　2019

ISSN：1348-2939
バイオニックヒューマノイドプラットフォームと要素技術の成果

益田泰輔, 小俣誠二, 相原一, 森田明夫, 金太一, 齊藤延人, 山下樹里, 鎮西清行, 福田敏男, 太田信, 芳賀洋一, 光石衛, 原田香奈子, 新井史人

日本生体医工学会大会プログラム・抄録集(Web)　57　(0)　S203_2-S203_2　2019
Publisher: 公益社団法人日本生体医工学会
DOI： 10.11239/jsmbe.Annual57.S203_2 　

ISSN：1347-443X
Compliance effect on the flow condition in vascular in vitro experiments Peer-reviewed

Masami Matsuura, Simon Tupin, Makoto Ohta

ASME 2018 International Mechanical Engineering Congress and Exposition　IMECE2018　87362(1)--87362(7)　2018/11
Permeability studies for the improvement of medical devices

Simon Tupin, Makoto Ito, Makoto Ohta

15th ICFD (Internatinal Conference of Fluid Dynamics)　2018/11
Hemodynamic Study on Coronary Artery Aneurysms with Bypass Surgery

Haoran Wang, Hitomi Anzai, Makoto Ohta, Youjun Liu

15th ICFD (Internatinal Conference of Fluid Dynamics)　2018/11
Research on Arterial Stiffness in Type 2 Diabetic Patients Based on Pulse Wave Analysis

Gaoyang Li, Xiaorui Song, Aike Qiao, Makoto Ohta

15th ICFD (Internatinal Conference of Fluid Dynamics　2018/11
3Dプリンタを用いたPVA‐H血管モデル作製用複合機の開発(第一報)

長野凌太, 清水康智, 吉田洋, 松永忠雄, 葛迫淳一, 木原信宏, 芳賀洋一, 芳賀洋一, 太田信, 太田信

日本シミュレーション外科学会会誌　26　(2)　127-127　2018/10
Publisher: 日本シミュレーション外科学会
ISSN：1348-6918
バイオニックヒューマノイドの開発と評価

山下樹里, 原田香奈子, 太田信, 鎮西清行

ヒューマンインタフェースシンポジウム論文集(CD-ROM)　2018　ROMBUNNO.7C2‐1　2018/09/05

ISSN：1345-0794
PIV MEASUREMENT IN AN IDEAL ANEURYSMAL MODEL USING A TRANSPARENT COIL MODEL Peer-reviewed

Makoto OHTA, Masanori KUZE, Simon TUPIN, Kaihong YU, Yasutomo SHIMIZU, Hitomi ANZAI

Conference on Modelling Fluid Flow (CMFF’18)　2018/07
Dose hypertension history affect morphology or hemodynamic characteristics of Cerebrobasilar System? Retrospetive study of 249 patients diagnosed with hypertension. Peer-reviewed

Yujie Li, Mingzi Zhang, Ko Kitamura, Hitomi anzai, Shuji Mugikura, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Characteristics of Elasticity on Flow Behavior in Middle Cerebral Aneurysm Model Peer-reviewed

Ryuhei Yamaguchi, Gaku Tanaka, Taihei Kotani, Kahar Osman, Nadia Shafii, Hitomi Anzai, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Drilling of PMMA-based bone biomodel: effect of temperature elevation during drilling Peer-reviewed

Yuta Muramoto, Gaëtan Bouvard, Vincent Fridrici, Philippe Kapsa, Fredrik Lundell, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Experimental analysis of AAA treatment by multi-layer stent and fate of abdominal aortic branches Peer-reviewed

Simon Tupin, Kei Takase, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Can morphology or haemodynamic characteristics of verteebrobasilar system be identifier of hypertension Peer-reviewed

Ko Kitamura, Yujie Li, Mingzi Zhang, Hitomi Anzai, Shuji Mugikura, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Multiobjective Optimization of Stent Design towards In-Stent Restenosis

Narendra Kurnia Putra, Pramudita Satria Palar, Hitomi Anzai, Koji Shimoyama, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Design of fabrication machine for 3-dimensional hydrogel blood vessel biomodels

Yasutomo Shimizu, Hiroshi Yoshida, Tadao Matsunaga, Yoichi Haga, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Analysis of relationship between aneurysmal flow and stent struts by using the lattice Boltzmann method

渡邉和浩, 安西眸, 太田信

計算工学講演会論文集(CD-ROM)　23　4p　2018/06
Publisher: 日本計算工学会
ISSN：1342-145X
脳動脈瘤抽出用ニューラルネットワークにおける,入力画像の表現方法の違いによる判定精度への影響

渡邉和浩, 安西眸, JUCHLER Norman, HIRSCH Sven, BIJLENGA Philippe, 太田信

バイオエンジニアリング講演会講演論文集(CD-ROM)　31st　2018

ISSN：2424-2829
Development of blood vessel model for bionic humanoid

SHIMIZU Yasutomo, ARAI Fumihito, HARADA Kanako, OHTA Makoto, YU Kaihong, TUPIN Simon, YOSHIDA Hiroshi, MATSUNAGA Tadao, MASUDA Taisuke, KIN Taichi, SHOJIMA Masaaki, HAGA Yoichi

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)　2018　(0)　1P1-J03　2018
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmermd.2018.1P1-J03 　

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Blood vessel models for medical training have been developed to represent realistic geometries and mechanical properties of the realistic blood vessels. However, few models were developed for assembling the other organ models. The purpose of this study is to develop a new blood vessel model which can be mounted on the Bionic Humanoid. The geometries and the mechanical properties of realistic cerebral arteries were represented using poly (vinyl alcohol) hydrogel (PVA-H) and silicone. We observed the PVA-H model can be ruptured depending on the force on the catheters and the guidewires during operations. This result cannot be observed using the previous blood vessel models produced from silicone or the other materials, and this observation indicates the PVA-H model can represent the realistic situations in operations.
Fabrication, Observation and Tribological Characterization of Acrylic Composite Materials for Bone Biomodel for Surgical Drilling

Yuta Muramoto, Gaëtan Bouvard, Makoto Ohta, Vincent Fridrici, Philippe Kapsa

30ème Jornées Internationals Francophones de Tribologie (JIFT2018)　2018
バイオエンジニアリング部門：「脳神経血管内治療に関する医工学連携研究会（A-TS02-16）」の紹介(<小特集>脳神経血管内治療に関する医工学連携研究)

太田信, 高嶋一登

日本機械学会誌　121　(1197)　28-29　2018
Publisher: 一般社団法人日本機械学会
DOI： 10.1299/jsmemag.121.1197_28
生体組織モデル工学のすすめ(<小特集>脳神経血管内治療に関する医工学連携研究)

太田信, 清水康智

日本機械学会誌　121　(1197)　30-30　2018
Publisher: 一般社団法人日本機械学会
DOI： 10.1299/jsmemag.121.1197_30
183 Development and evaluation of new fabrication machine for hydrogel blood vessel models

SHIMIZU Yasutomo, YOSHIDA Hiroshi, MATSUNAGA Tadao, HAGA Yoichi, OHTA Makoto

The Proceedings of Conference of Tohoku Branch　2018　(0)　163-164　2018
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2018.53.163 　
Sensory Evaluation of Cerebral Artery Blood Vessel Model using PVA-H

YU Kaihong, TUPIN Simon, SHOJIMA Masaaki, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2018　(0)　2I02　2018
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2018.30.2I02 　
Development of device placement simulator for endovascular treatment:(Visualization of contact state between coil and aneurysm model)

HAYASHIDA Norihiro, SUZUKI Hidenori, TAKASHIMA Kazuto, YOSHINAKA Kiyoshi, YU Kaihong, OHTA Makoto, MORI Koji, TOMA Naoki, SANO Takanori, UMEDA Yasuyuki

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2018　(0)　2I05　2018
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2018.30.2I05 　
Location related variability of permeability characteristics in cancellous bone

Ito Makoto, Tupin Simon, Anzai Hitomi, Suzuki Anna, Ohta Makoto

Proceedings of the 14th International Conference on Flow Dynamics　834-835　2017/11
海綿骨内における浸透率測定

伊藤誠, TUPIN Simon, 安西眸, 鈴木杏奈, 太田信

日本バイオレオロジー学会誌(Web)　31　(2)　2017

ISSN：2186-5663
血管モデルの開発と動物実験

太田信, 大西泰平, TUPIN Simon, 清水康智, 于凱鴻, 安西眸

日本実験動物学会総会講演要旨集　64th　2017
教育用,評価用,プレオペ用血管モデルの開発

太田信, 清水康智, 于凱鴻, TUPIN Simon, 安西眸

日本医学放射線学会秋季臨床大会抄録集　53rd　2017

ISSN：0048-0428
Development of device placement simulator for endovascular treatment:(Evaluation of deformation behavior of coil using blood vessel biomodel)

HAYASHIDA Norihiro, UMEDA Yasuyuki, TAKASHIMA Kazuto, YOSHINAKA Kiyoshi, YU Kaihong, OHTA Makoto, MORI Koji, TOMA Naoki, SUZUKI Hidenori, SANO Takanori

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2017　(0)　2B32　2017
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2017.29.2B32 　
MFM evaluation using a flow rate and pressure controlled in-vitro model

TUPIN Simon, SHIMIZU Yasumoto, OHTA Makoto, ANZAI Hitomi

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2017　(0)　2B34　2017
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2017.29.2B34 　
Verification, Validation, and Standardization of "Bionic Humanoid"

YAMASHITA Juli, OHTA Makoto, CHINZEI Kiyoyuki

The Proceedings of Mechanical Engineering Congress, Japan　2017　(0)　W241004　2017
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2017.W241004 　

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Recently, a wide variety of human organ simulators, such as virtual reality (VR) and 3D printed models, have been developed for medical education and for development of new medical equipment. Although expectations for such simulators to replace animal and human subjects are high, their validation and verification (V&V) processes are not clear yet. Our goal is to define "biofidelity" of organ models, that is the degree of their exactness to real organs with appropriate V&V processes. The result will be submitted to ISO as a new proposal.
Development of Biomodel with Micro particles for Ultrasound Diagnostic System

TAKAHASHI Ren, YAMAGUCHI Tadashi, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2017　(0)　J0240304　2017
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2017.J0240304 　

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Phantoms for ultrasonography have been widely used to improve skills of physicians and techniques of ultrasonic scattering. Several kinds of phantoms for ultrasonography have already been developed using gelatin, Polyacrylamide. In the development of biomodel for ultrasonography that covers human soft tissue, to change the mechanical properties widely is useful. We chose a poly (vinyl alcohol) hydrogel (PVA-H) to mimic human soft tissue. The purpose of this study is to measure the mechanical properties with varieties of concentration of solvent of PVA solution. The ratio of the mixed solution of Dimethyl sulfoxide (DMSO) and water was changed. The measurement of the static viscoelasticity, the dynamic viscoelasticity, and the loss tangent of PVA-H were performed. In addition, we measured the transverse wave velocity for the phantom to which graphite was added. In conclusion, the variety of mechanical properties of PVA-H is shown by the change of solvents, and especially the loss tangent is twice higher than the conventional PVA-H. And the transverse wave velocity has also a relation to the solvents.
Haemodynamic simulation of flow-diverting stent efficacy using porous medium method

LI Yujie, ZHANG Mingzi, SEN Itsu, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2017　(0)　J0230205　2017
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2017.J0230205 　

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Flow-diverting (FD) stent is a commonly adopted devices for the minimally-invasive treatment of intracranial aneurysm (IA). With a FD stent properly deployed across the aneurysm orifice, it may discourage the flow from entering the aneurysm, thereby reducing the chance of aneurysm rupture. Using computational fluid dynamics (CFD) method, the aneurysmal haemodynamcis can be resolved to observe the flow-diversion efficacy and estimate the condition of aneurysm. Modelling the FD stent as a porous medium (PM) in the simulation, as an alternative to the original fully-resolved wire FD stent, is discovered to be an useful and flexible method to obtain the flow-diversion efficacy with improved simulation efficiency. However, current simulations with PM model FD stent tend to define the properties of the PM with consistent value, which fail to represent the different flow resistance result from the specific wire configurations in each stent of interest. Therefore, in this study, we aim to investigate a set of parameters for the calibrated PM stent model to represent a variety of commercially available FD stents and different treatment modes. The sensitivity in flow-diversion effects was observed with regard to the designing of PM model thickness and parameter settings of the PM model properties. Results indicate that the PM model thickness has negligible influence to the aneurysmal haemodynamics as long as the flow resistance are compensated to be identical, while the definition of PM properties, such as the permeability (k) and inertial resistance factor (C2), can induce flow-diversion effects with marked difference.
Introduction of numerical simulation being applied to the study of aneurysm treatment with flow-diverting stent

ZHANG Mingzi, LI Yujie, ANZAI Hitomi, SEN Itsu, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2017　(0)　J0230204　2017
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2017.J0230204 　

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Intracranial aneurysms (IAs) account for a large portion of cerebrovascular disorders and can be treated with flow-diverting (FD) stents. To aid the treating clinicians with determination of a favourable treatment plan, we adopted numerical simulation methods to the optimisation of FD treatment, including the design optimisation of FD stent wire structure, as well as the optimisation of FD stent treatment procedure. Our simulation results suggest that both stent design and stent deployment may drastically affect the FD treatment outcomes; numerical simulation prior to the real treatment may therefore assist the treating clinicians in predicting the treatment outcomes.
Bionic Humanoid: Design of Humanoid Model for Next Generation Surgical Training

ARAI Fumihito, MORI Kensaku, SAITO Nobuhito, AIHARA Makoto, HARADA Kanako, MASUDA Taisuke, OHTA Makoto, FUKUDA Toshio, KIHARA Nobuhiro, YAMASHITA Juli, CHINZEI Kiyoyuki, HAGA Yoichi, MARUYAMA Hisataka

The Proceedings of JSME annual Conference on Robotics and Mechatronics (Robomec)　2017　(0)　2A1-N07　2017
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmermd.2017.2A1-N07 　

ISSN：2424-3124

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Along with technological innovation of rapid prototyping, an artificial organ model with high shape and color reproducibility has become relatively easy to prepare and obtain. However there are few artificial organ models that reproduce physical properties such as hardness, softness, and surface friction characteristics. This study proposes to use "Bionic Humanoid" to quantitatively understand qualitative sensory expressions and quickly deliver technology seeds to society by eliminating trial and error. The Bionic Humanoid is an elaborate model of a human body equipped with sensors, to quantify such sensory expressions. The Bionic Humanoid can be used, for example, to quantify the requirements of medical doctors, assess surgical skills, replicate physical constraints for the development of a medical device, and provide young surgeons with training opportunities. We here describe a design concept and a prototype development of Bionic Humanoid.
Advanced Technologies of Medical Active Catheter:―Minimally Invasive Medicine Considering Friction―

HAGA Yoichi, OHTA Makoto, MATSUNAGA Tadao

JOURNAL OF JAPANESE SOCIETY OF TRIBOLOGISTS　62　(1)　30-36　2017
Publisher: Japanese Society of Tribologists
DOI： 10.18914/tribologist.62.01_30 　

ISSN：0915-1168
皮膚組織を貫通する人工物の癒着強度評価試験のための基礎検討

弓場充, 坪子侑佑, 白石泰之, 井上雄介, 平恭紀, 太田信, 山家智之

人工臓器　45　(2)　S-159　2016/10
Publisher: (一社)日本人工臓器学会
ISSN：0300-0818

eISSN：1883-6097
1D45 TGF-β1 from endothelial cells under shear stress influences smooth muscle cell phenotype in a co-culture model

HAN Xiaobo, Sakamoto Naoya, Tomita Noriko, Hui Meng, Sato Masaaki, Ohta Makoto

2016　(28)　"1D45-1"-"1D45-3"　2016/01/09
Publisher: The Japan Society of Mechanical Engineers

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Vascular smooth muscle cells (SMCs) are suggested to make functional changes under shear stress (SS) stimulation through intercellular communication with endothelial cells (ECs). In the present study, we constructed an EC-SMC co-culture model with phenotype-controlled SMCs, which is similar to normal healthy arterial walls, and then explored relationship between EC gene (TGF-β1) expression and SMC phenotype change under SS conditions. The result shows that the expression of contractile proteins in SMCs were at same level under 0.2, 2,6 or 10 Pa when TGF-β1 expression from EC was knocked down by SiRNA. In our previous experiment, we have reported that a low SS (0.2 Pa) or a high SS (10 Pa) could suppress the expression of contractile proteins in SMCs in a co-cultured model, therefore the present result suggests that TGF-β1 expression from EC could influence SMC response to SS.
低レイノルズ数領域における血液環流フローチャンバーシステムの開発

安西眸, 白石泰之, 山家智之, 太田信

日本バイオレオロジー学会誌(Web)　30　(2)　2016

ISSN：2186-5663
AVEC CFD2016

安西眸, TUPIN Simon, 渡邉和浩, RASHAD Sherif, 太田信

日本バイオレオロジー学会誌(Web)　30　(2)　2016

ISSN：2186-5663
脳血管内治療デバイスと治療の有効性を予測する血管モデルの開発

太田信, TUPIN Simon, 清水康智, 于凱鴻, 安西眸

脳血管内治療(Web)　1　(Supplement)　2016

ISSN：2424-1709
Effect of elasticity on wall shear stress inside cerebral aneurysm at anterior cerebral artery (vol 24, pg 349, 2016)

Lijian Xu, Michiko Sugawara, Gaku Tanaka, Makoto Ohta, Hao Liu, Ryuhei Yamaguchi

TECHNOLOGY AND HEALTH CARE　24　(4)　605-605　2016
Publisher: IOS PRESS
DOI： 10.3233/THC-161242 　

ISSN：0928-7329

eISSN：1878-7401
Development of Artery Biomodel for Endovascular Treatment

Ohta Makoto, Shimizu Yasutomo, Tupin Simon, Onishi Taihei, Muramoto Yuta, Seiller Joanna, Yu Kaihong, Anzai Hitomi

The Proceedings of Mechanical Engineering Congress, Japan　2016　(0)　W021003　2016
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2016.W021003 　

ISSN：2424-2667
2F25 Development of device placement simulator for endovascular treatment : Evaluation of deformation behavior of catheter using PVA-H blood vessel biomodel

OIKE Atomu, TAKASHIMA Kazuto, YOSHINAKA Kiyoshi, YU Kaihong, OHTA Makoto, MORI Koji

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　28th　(0)　_2F25-1_-_2F25-5_　2016
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2016.28._2F25-1_ 　

ISSN：2424-2829

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We have developed a computer-based system to simulate a guidewire and a catheter in blood vessels for surgical planning, intra-operative assistance, and to facilitate the design of new guidewires and catheters. We have also developed an experimental apparatus which can be used not only for the validation of the numerical analyses but also as a simulation system. However, we have not evaluated the catheter motion in the experimental apparatus. Therefore in this study, first we added a mechanism to move the catheter to the experimental apparatus. Second, we evaluated the deformation behaviors of the guidewire and the catheter by the measurement of the 3D position and the contact force between the medical devices and the vessel. Finally, we compared the calculation results with the experimental results. The same tendency was seen in the trajectories and the contact force of both the experimental and calculated guidewire and catheter tips.
2F23 Development of In-vitro Model for Evaluation of Endoleak and Migration on Stent Graft

Onishi Taihei, Li Yujie, Oppata Shusaku, Idei Tadashi, Ohta Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　28th　(0)　_2F23-1_-_2F23-4_　2016
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2016.28._2F23-1_ 　

ISSN：2424-2829

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Stent grafting is one of the treatments for thoracic aortic aneurysm that is less invasive than open surgery. However, it sometimes involves in serious problems: Endoleak and Migration. These problems seem to have a relation to the oversize of stent or wrong position of stent on the arterial wall, and so the evaluation of the problems should be performed quantitatively using in-vitro model with observation of sealing. The purpose of this research is the development of in vitro model made of PVA-H (Poly Vinyl Alcohol Hydrogel) for evaluation of endoleak and migration on stent graft. We used Dip-Coating method to make the model. Dip-Coating is the method which forms a liquid film on the surface of the mold (Nylon12) by dipping the mold in PVA-H. As the result, the method using Nylon12 as a material of the mold enables to make the model with a similar surface roughness to the conventional method. In addition, the model has a high transparency and will be used for PIV.
2F22 The effect of strut position relative to inflow zone of aneurysm neck on flow

WATANABE Kazuhiro, ANZAI Hitomi, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2016　(0)　_2F22-1_-_2F22-4_　2016
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2016.28._2F22-1_ 　

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For the treatment of cerebral aneurysms, flow diverter (FD) stent placement has been attracted. To evaluate a positioning error of stent on aneurysm flow, we analyze an influence of strut positions with relation to the inflow zone. Lattice Boltzmann flow simulation was applied to compute flow velocity in 3-D ideal aneurysm with a curved parent artery. Rectangular solid as a strut model was placed along to the neck plane. The results suggest that the flow velocity in the aneurysm is effectively reduced when the flow in the aneurysm and parent vessel flow are separated by a strut.
Effect of vibration on cooling to ablation catheter

Ohta Makoto, Yu Kaihong, Yamashita Tetsui, Shingyochi Shigeaki, Matsumoto Kazuo

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　28th　(0)　B4　2016
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2016.28.B4 　

ISSN：2424-2829
135 Development of Working Fluid for Matching Viscosity for Evaluation of Ablation Catheter

TAKAHASHI Ren, YU Kaihong, OHTA Makoto

The Proceedings of Conference of Tohoku Branch　2016　(0)　67-68　2016
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2016.51.67 　
脳動脈瘤の生化学的イベントと数値流体解析の応用に関するCutting‐Edge

安西眸, ZHANG Mingzi, PUTRA Narendra Kurnia, 渡邉和浩, 太田信

脳血管内治療(Web)　1　(Supplement)　S47(J‐STAGE)　2016

ISSN：2424-1709
脳動脈瘤内の血液交換

杉山慎一郎, 太田信, 冨永悌二

日本機械学会バイオフロンティア講演会講演論文集　26th　23‐24　2015/10/01

ISSN：1348-2939
PS5-4 CFD analyses for the flow in cancellous bone with LBM(PS5: Poster Short Presentation V,Poster Session)

Sakuma Wataru, Nakayama Toshio, Anzai Hitomi, Nakamura Shuji, Sado Katsuyuki, Kutscher Konstantin, Stiebler Maik, Geier Martin, Krafczyk Manfred, Ohta Makoto

Proceedings of the ... Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics　2015　(8)　302-302　2015/09/16
Publisher: The Japan Society of Mechanical Engineers
PS1-19 Lesion Size Comparison of Catheter Ablation between Open Irrigation and Vibration under No Flow Condition(PS1: Poster Short Presentation I,Poster Session)

Yu Kaihong, Yamashita Tetsui, Shingyochi Shigeaki, Matsumoto Kazuo, Ohta Makoto

Proceedings of the ... Asian Pacific Conference on Biomechanics : emerging science and technology in biomechanics　2015　(8)　240-240　2015/09/16
Publisher: The Japan Society of Mechanical Engineers
CFDで何をみるのか,見えるのか AVEC CFD2015

安西眸, 下權谷祐児, 太田信, 八木高伸, 高尾洋之, 河野健一, 庄島正明

日本バイオレオロジー学会年会プログラム・抄録集　38th　2015
A112 Turnover of blood inside cerebral aneurysms

SUGIYAMA Shin-ichiro, OHTA Makoto, TOMINAGA Teiji

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2015　(0)　23-24　2015
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2015.26.23 　

ISSN：1348-2939
S0220301 Design analysis of optimized stent for intracranial aneurysm using Self-organizing maps

ANZAI Hitomi, YOSHIDA Yuuki, SHIMOYAMA Koji, OBAYASHI Shigeru, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2015　(0)　_S0220301--_S0220301-　2015
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2015._S0220301- 　

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As evaluation of hemodynamics in an aneurysm, a lot of parameters have been introduced. However, the relationship between stent geometry and each hemodynamic parameter is not clear enough. We applied Self-organizing Maps (SOM) to search the detailed relationship between stent strut and hemodynamic parameters. Two thousands of stent design candidates evaluated with five hemodynamic parameters and 25 stent geometry parameters were stored during the optimization process. By using SOM software, 2,000 design candidates were visualized into 30 2D-maps while preserving their own features in the original 30-dimensional design space. Each map was divided into 20 clusters to characterize stent design and flow reduction. By comparing each cluster, critical design for reduction effect of each hemodynamic parameter is suggested. Strut placement on the inflow area is important to reduce maximum shear rate. In addition to the inflow area, strut on the outflow area is required to reduce velocity, vorticity, and average shear rate.
1B44 Study on catheter and guidewire simulator for intravascular surgery : Influence of guidewire shape

OIKE Atomu, TAKASHIMA Kazuto, YOSHINAKA Kiyoshi, YU Kaihong, OHTA Makoto, MORI Koji

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2015　(0)　91-92　2015
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2015.27.91 　
1B34 Comparison of flow pattern in cerebral aneurysm among PIV, CFD and MRI

LI Yujie, YONEYAMA Yuuya, ISODA Haruo, KOSUGI Takafumi, KOSUGI Takashi, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2015　(0)　79-80　2015
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2015.27.79 　
脳動脈瘤治療用ステントにおける自己組織化マップを用いた最適形状解析

安西眸, 吉田裕貴, 下山幸治, 大林茂, 太田信

日本機械学会年次大会講演論文集(CD-ROM)　2015　ROMBUNNO.S0220301　2015

ISSN：2424-2667
CFD analysis of flow in cancellous bone

Sakuma Wataru, Nakayama Toshio, Anzai Hitomi, Nakamura Shuji, Sado Katsuyuki, Takagawa Hirokazu, Ohta Makoto

The Computational Mechanics Conference　2014　(27)　366-367　2014/11/22
Publisher: The Japan Society of Mechanical Engineers
ISSN：1348-026X
血行力学的解析を主眼とする脳動脈瘤データベースの構築

杉山慎一郎, 太田信, 中山敏男, 清水宏明, 冨永悌二

東北大学流体科学研究所共同利用・共同研究拠点流体科学研究拠点活動報告書　2013　157-158　2014/10
脳動脈瘤治療用ステントにおける数値解析を用いた最適設計

安西眸, CHOPARD Bastian, 中山敏男, ZHANG Mingzi, 吉田裕貴, 太田信

計算工学講演会論文集(CD-ROM)　19　ROMBUNNO.D-3-2　2014/06/11
Publisher: 日本計算工学会
ISSN：1342-145X
Method for Numerical modelling of bone marrow flow around puncture needle

佐久間航, 太田信, 中山敏男

計算工学講演会論文集 Proceedings of the Conference on Computational Engineering and Science　19　3p　2014/06
Publisher: 日本計算工学会
2F46 Study on catheter and guidewire simulator for intravascular surgery : Three-dimensional tracking of guidewire in blood vessel model

TSUZUKI Shotaro, TAKASHIMA Kazuto, YOSHINAKA Kiyoshi, YU Kaihong, OHTA Makoto, MORI Koji

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2014　(0)　517-518　2014
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2014.26.517 　
2F43 Development of System for Evaluation of Electrode Temperature on Ablation Catheter

YU Kaihong, YAMASHITA Tetsui, SHINGYOCHI Shigeaki, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2014　(0)　511-512　2014
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2014.26.511 　
326 Development of guidewire simulator for intravascular surgery : Comparison between experimental results using PVA-H blood vessel biomodel and simulation results

TSUZUKI Shotaro, TAKASHIMA Kazuto, YOSHINAKA Kiyoshi, YU Kaihong, OHTA Makoto, MORI Koji

The Proceedings of Conference of Kyushu Branch　2014　(0)　_326-1_-_326-2_　2014
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmekyushu.2014.67._326-1_ 　
S0220202 Influence of Surface Treatment of Ni-Ti Wire under the Shear Stress Environment on Endothelialization

MATSUMOTO Sho, Han XIAOBO, KOBAYASHI Hisatoshi, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2014　(0)　_S0220202--_S0220202-　2014
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2014._S0220202- 　

ISSN：2424-2667

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Stent placement for stenosis has possibility of restenosis by intimal excessive proliferation with denudation of intima by stent placement. The goal of stent treatment is to cover the layer of endothelial cells (EC) on and around the stent. Intimal excessive proliferation is not occurred in the area with ECs. So, cell adhesive treatment for stent will suppress restenosis. To investigate the effect of surface treatment of Ni-Ti wire for stent under flow on endothelialization on implanted stent, we measured the density of ECs on and around the wire which was implanted on cultured ECs under shear stress (SS) environment. The treatment of collagen immobilization on Ni-Ti wire effects on the cell density on and around the wire. On collagen immobilized wire, ECs are attaching on lager area on wire than on wire without surface treatment. This mean that cell adhesive treatment by collagen immobilization promoted endothelialization.
CFD analysis of flow in cancellous bone

Sakuma Wataru, Nakayama Toshio, Anzai Hitomi, Nakamura Shuji, Sado Katsuyuki, Takagawa Hirokazu, Ohta Makoto

The Proceedings of The Computational Mechanics Conference　27th　(0)　366-367　2014
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmecmd.2014.27.366 　

ISSN：2424-2799
1204 Design Optimization of intracranial stent to encourage blood coagulation in aneurysm

Yoshida Yuuki, Anzai Hitomi, Ohta Makoto

Proceedings of the Optimization Symposium　2014　(0)　_1204-1_-_1204-3_　2014
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeopt.2014.11.0__1204-1_ 　

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Flow diverter stent (FD) is one of an efficient medical device or intracranial aneurysm. FD is a cylindrical device woven from metallic wires. It blocks the inflow entering an aneurysm to make blood coagulation in the aneurysm. But the device has a risk of blood coagulation as well in the parent artery attributable to chemical reactions between metal and blood. Therefore, we have developed the optimization program for mesh design of FD with simulated annealing and computational fluid dynamics to improve the treatment effect maintaining low wire density. In this report, we investigate the relationship between hemodynamic parameters and mesh design to determine the objective function for FD optimization.
Design Optimization of intracranial stent to encourage blood coagulation in aneurysm

吉田裕貴, 安西眸, 太田信

日本機械学会最適化シンポジウム(CD-ROM)　11th (Web)　3p　2014
Publisher: 日本機械学会
医療機器開発と最適化手法の接点(トピックス)

太田信

日本機械学会誌　117　(1150)　634-634　2014
Publisher: 一般社団法人日本機械学会
DOI： 10.1299/jsmemag.117.1150_634 　

ISSN：0021-4728

eISSN：2424-2675
血行力学的解析を主眼とする脳動脈瘤データベースの構築

杉山慎一郎, 太田信, 中山敏男, 清水宏明, 冨永悌二

東北大学流体科学研究所共同利用・共同研究拠点流体科学研究拠点活動報告書　2012　109-110　2013/10
S022023 Study on guidewire simulator for intravacular surgery : Improvement of simulation model based on experimental results

TAKASHIMA Kazuto, TSUZUKI Shotaro, YOSHINAKA Kiyoshi, HOSHINO Yusuke, OHTA Makoto, MORI Koji

The Proceedings of Mechanical Engineering Congress, Japan　2013　(0)　_S022023-1-_S022023-3　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2013._S022023-1 　

ISSN：2424-2667

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We have developed a system to simulate a guidewire in blood vessels for surgical planning,intra-operative assistance and the design of new guidewires.In this study,we compared the simulation results with the experimental results for validation of the simulation system and evaluated the parameters of guidewire model.The model of the guidewire is constructed with viscoelastic springs and segments.The proximal part of the guidewire model is constrained by the catheter model,which is fixed and assumed to be a rigid tube.The motion of the guidewire in torus-shaped blood vessel model was calculated when the proximal part of the guidewire model was pushed and twisted.Collisions between the guidewire and the vessel are calculated and the contact forces are determined according to the stiffness of the vessel wall.The same tendency was seen in the trajectory of the both guidewire tips.The viscous term,the friction,the number of the segments affected the motion of the guidewire tip.
S021015 Change of MMP production by vascular smooth muscle cells in a co-culture model exposed to fluid shear stress

Han Xiaobo, Sakamoto Naoya, Tomita Noriko, Hui Meng, Sato Masaaki, Ohta Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2013　(0)　_S021015-1-_S021015-4　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2013._S021015-1 　

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Vascular smooth muscle cells(SMCs) are suggested to make functional changes under shear stress(SS) stimulation through intercellular communication with endothelial cells(ECs).In the present study,we constructed an EC-SMC coculture model with phenotype-controlled SMCs,which is similar to normal healthy arterial walls,and then explored relationship between SS and matrix metalloproteinases-2(MMP-2) production from SMC in the model.The result shows that application of a physical level SS of 2 Pa to endothelial cells in the model suppressed the expression of activated MMP-2 by SMCs compared to the statically cultured model,while MMP-2 production by SMCs did not decrease under a low SS of 0.2 Pa or a high SS of 10 Pa.Since MMP-2 could degrade extracellular matrix(ECM),activity of MMP-2 under low or high SS might be related to pathological remodeling of blood vessels.These results could help better understanding of relationship between the local hemodynamics and the development of vascular diseases.
3C08 Design optimization of flow diverter stent using realistic aneurysm

ANZAI Hitomi, FALCONE Jean-Luc, CHOPARD Bastien, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2013　(0)　535-536　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2013.25.535 　
3C07 Classification of cerebral aneurysm on parent artery configuration and optimized stent strut pattern

NAKAYAMA Toshio, JEONG Shinkyu, SRINIVAS Karkenahalli, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2013　(0)　533-534　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2013.25.533 　
2C16 The relationship between geometrical change based on inlet pressure and blood flow pattern in a stenotic vessel

SHIMIZU Yasutomo, LIU Lei, SHIDA Shuya, FUNAMOTO Kenichi, HAYASE Toshiyuki, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2013　(0)　343-344　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2013.25.343 　
2C14 Phenotypic responses of vascular smooth muscle cells in a co-culture model exposed to fluid shear stress

Han Xiaobo, Sakamoto Naoya, Tomita Noriko, Hui Meng, Sato Masaaki, Ohta Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2013　(0)　339-340　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2013.25.339 　
1F11 Study on guidewire simulator for intravascular surgery : Comparison between simulation and experimental results using blood vessel model

TSUZUKI Shotaro, YOSHINAKA Kiyoshi, HOSHINO Yusuke, OHTA Makoto, MORI Koji, TAKASHIMA Kazuto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2013　(0)　199-200　2013
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2013.25.199 　
Computational fluid dynamics of carotid arteries after carotid endarterectomy or carotid artery stenting based on postoperative patient-specific medical data

Hayase Hitoshi, Date Isao, Tokunaga Koji, Nakayama Toshio, Sugiu Kenji, Nishida Ayumi, Arimitsu Seiji, Hishikawa Tomohito, Ono Shigeki, Ohta Makoto

Okayama Igakkai Zasshi (Journal of Okayama Medical Association)　125　(1)　5-7　2013
Publisher: Okayama Medical Association
DOI： 10.4044/joma.125.5 　

ISSN：0030-1558
Optimization of intracranial stent design for flow reduction

Ohta Makoto, Anzai Hitomi, Nakayama Toshio

NCTAM papers, National Congress of Theoretical and Applied Mechanics, Japan　62　(0)　200-200　2013
Publisher: National Committee for IUTAM
DOI： 10.11345/japannctam.62.0.200.0 　

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The design optimization of stents (or flow diverters) from the view point of fluid dynamics has attracted attentions in recent years. However, the conventional optimization requires huge time and efforts to generate geometries and meshes. Therefore we have introduced the possibility to use lattice Boltzmann (LB) flow simulations in combination with simulated annealing (SA) optimization that explore the design of stents for 2-D aneurysms, in a fully automated way.This report demonstrates the optimization for 3-D aneurysm with two different objectives. As the result, optimum stent varies with the objectives.
脳動脈瘤における動脈硬化性変化と血行動態との関係

杉山慎一郎, 中山敏男, 太田信, 清水宏明, 藤原悟, 冨永悌二

日本神経放射線学会プログラム・抄録集　42nd　144　2013
血行力学的解析を主眼とする脳動脈瘤データベースの構築

杉山慎一郎, 太田信, 中山敏男, 清水宏明, 冨永悌二

東北大学流体科学研究所共同利用・共同研究拠点流体科学研究拠点活動報告書　2011　85-86　2012/10
脳動脈瘤用フローダイバータステントモデル化に対する圧力勾配と瘤内流れに関する研究

三浦幸久, 安西眸, 中山敏男, 太田信

日本機械学会東北支部総会・講演会講演論文集　47th　20‐21　2012/03/13
Micro‐CTによる脳動脈瘤コイルモデルの可視化に関する研究

久世政範, 太田信

日本機械学会東北支部総会・講演会講演論文集　47th　34‐35　2012/03/13
脳動脈瘤の形状による分類とステントの最適化

中山敏男, JEONG Shinkyu, SRINIVAS Karkenahalli, 太田信

バイオエンジニアリング講演会講演論文集　24th (CD-ROM)　ROMBUNNO.7F26　2012/01/06

ISSN：1348-2920
格子ボルツマン法を用いた脳動脈瘤治療用ステントの形状最適化プログラムの開発

安西眸, FALCONE Jean‐Luc, CHOPARD Bastien, 太田信

バイオエンジニアリング講演会講演論文集　24th (CD-ROM)　ROMBUNNO.7F24-_7F24-2_　2012/01/06
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2012.24._7f24-1_ 　

ISSN：1348-2920

eISSN：2424-2829
血管壁の動きを考慮したPVA脳動脈瘤バイオモデル内拍動流れのPIV計測

信太宗也, 太田信

バイオエンジニアリング講演会講演論文集　24th (CD-ROM)　ROMBUNNO.8F35　2012/01/06

ISSN：1348-2920
医療デバイス周りの血流流体力学的見地からの血栓形成

太田信, WETZEL S., 安西眸, 中山敏男, HAN Xiaobo, 清水康智, 小澤桂, 冨田典子

日本バイオマテリアル学会シンポジウム予稿集　2012　2012
S021022 Automated Optimization of Strut Position for Intracranial Aneurysm

ANZAI Hitomi, FALCONE Jean-Luc, CHOPARD Bastien, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2012　(0)　_S021022-1-_S021022-3　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2012._S021022-1 　

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To produce an optimal design of stents for cerebral aneurysm is attracted for reducing the flow in the aneurysm efficiently. This report demonstrates the optimization for 3-D aneurysm with two different objectives. As the result, the optimum stent for the maximum velocity has denser struts on distal of the neck. On the other hand, the optimum stent for average velocity has denser struts on proximal of the neck.
S021021 Study on development of stent using optimization to stent strut patternr

NAKAYAMA Toshio, JEONG Shinkyu, SRINIVAS Karkenahalli, OHTA Makoto

The Proceedings of Mechanical Engineering Congress, Japan　2012　(0)　_S021021-1-_S021021-5　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecj.2012._S021021-1 　

ISSN：2424-2667

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Stent implantation in intracranial arteries is termed as endovascular treatment. The number of such cases has been increasing worldwide because the surgical damage resulting from stenting seem to be less than that of other treatments. A side wall type idealized aneurysm shape reconstructed by straight pipe and half sphere were used, Z-type stent was used. CFD analysis was performed each aspect ratio aneurysm and stent strut pattern. The optimization by the process of Multi-Objective Genetic Algorithm and Kriging was performed to the CFD results From the results, we report the development of new stent strut pattern in cerebral aneurysm using the computational fluid dynamics (CFD) and optimization.
114 Visualization of coil biomodel for cerebral aneurysm using Micro-CT.

KUZE Masanori, OHTA Makoto

The Proceedings of Conference of Tohoku Branch　2012　(0)　34-35　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2012.47.34 　
107 Relationship between Pressure Gradient and Flow in Aneurysm for Modeling Flow Diverter Stent in Cerebrl Aneurysm

MIURA Yukihisa, ANZAI Hitomi, NAKAYAMA Toshio, OHTA Makoto

The Proceedings of Conference of Tohoku Branch　2012　(0)　20-21　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2012.47.20 　
A104 Effect of cooling time of Thickness distribution of arterial wall for Poly (vinyl alcohol) Hydrogel Biomodel

Ohtake Masahi, Ohta Makoto

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2012　(0)　7-8　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2012.23.7 　

ISSN：1348-2939
8F36 Influence of plaque stiffness on steady flow with blood vessel stenosis biomodel

SHIMIZU Yasutomo, SHIDA Shuya, HAYASE Toshiyuki, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2012　(0)　_8F36-1_-_8F36-2_　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2012.24._8F36-1_ 　
8F35 PIV measurement of pulsatile flow in PVA biomodel with compliant wall of cerebral aneurysm.

SHIDA Shuya, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2012　(0)　_8F35-1_-_8F35-2_　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2012.24._8F35-1_ 　
8E23 Development of the Thickness Control Mechanism of the PVA-H Blood Vessel Biomodel

KIYOMITSU Chihaya, KOSUKEGAWA Hiroyuki, KUROKI Kanju, TAKASHIMA Kazuto, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2012　(0)　_8E23-1_-_8E23-2_　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2012.24._8E23-1_ 　
7F26 Optimization of Stent Strut Pattern for Classified Cerebral Aneurysm.

NAKAYAMA Toshio, JEONG Shinkyu, SRINIVAS Karkenahalli, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2012　(0)　_7F26-1_-_7F26-2_　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2012.24._7F26-1_ 　
7F24 Development of optimization program for flow diverters based on lattice Boltzmann method

ANZAI Hitomi, FALCONE Jean-Luc, CHOPARD Bastien, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2012　(0)　_7F24-1_-_7F24-2_　2012
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2012.24._7F24-1_ 　
脳動脈瘤に対するステントストラット位置の自動最適化に関する研究

安西眸, FALCONE Jean‐Luc, CHOPARD Bastien, 太田信

日本機械学会年次大会講演論文集(CD-ROM)　2012　ROMBUNNO.S021022　2012

ISSN：2424-2667
Hemodynamic of an Unruptured Cerebral Aneurysm before Its Rupture : Predicting the Risk of a Cerebral Aneurysm Rupture Using Computational Fluid Dynamics

IRIE Keiko, OHTA Makoto, ANZAI Hitomi, NEGORO Makoto, HIROSE Yuichi

CI研究　33　(2)　119-125　2011/09/30

ISSN：0918-7073
未破裂脳動脈瘤の破裂リスクに関する3次元可視化システムを用いたCFD解析の試み

入江恵子, 太田信, 安西眸, 中山敏男, 根來真, 廣瀬雄一

日本バイオレオロジー学会年会プログラム・抄録集　34th　53　2011/06/03
次世代の画像解析ソフトウェアサブトラクションソフトによる脳動脈瘤の評価―ソフトウェアの開発評価とその展望

茅野伸吾, 黒田英隆, 梁川功, 高橋明, 太田信

Innervision　26　(3)　18-21　2011/02/25

ISSN：0913-8919
NBCA-Lipiodol混合液による動脈塞栓効果の基礎的検討

高澤千晶, 清治和将, 松永賢一, 高瀬圭, 高橋昭喜, 松橋俊夫, 信太宗也, 太田信

日本医学放射線学会学術集会抄録集　70回　S316-S316　2011/02
Publisher: (公社)日本医学放射線学会
ISSN：0048-0428
血流数値解析の3次元可視化による効果的な脳動脈瘤ステント配置の予測

安西眸, 中山敏男, 入江恵子, 太田信

バイオエンジニアリング講演会講演論文集　23rd　253-254　2011/01/07

ISSN：1348-2920
最適化設計法による脳動脈瘤用ステントのストラットパターンの開発

中山敏男, JEONG Shinkyu, SRINIVAS Karkenahalli, 太田信

バイオエンジニアリング講演会講演論文集　23rd　251-252　2011/01/07

ISSN：1348-2920
A210 Evaluation of thermal distribution of ablation catheter using PVA biomodel

TAKAHASHI Ryotaro, YAMASHITA Tetsui, OHTA Makoto

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2011　(0)　97-98　2011
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2011.22.97 　

ISSN：1348-2939
8B-03 Friction Properties on Stent Metallic Alloy and Blood-vessel-like Soft Matter

KOSUKEGAWA Hiroyuki, FRIDRICI Vincent, KAPSA Philippe, STOIMENOV Boyko, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2010　(0)　17-18　2011
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2010.23.17 　
8F-14 Development of Stent Strut Pattern for Cerebral Aneurysm using Optimization Design Method

NAKAYAMA Toshio, JEONG Shinkyu, SRINIVAS Karkenahalli, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2010　(0)　251-252　2011
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2010.23.251 　
8F-15 Prediction of effective position for intracranial stent using 3D visualization of numerical analysis of blood flow

ANZAI Hitomi, NAKAYAMA Toshio, IRIE Keiko, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2010　(0)　253-254　2011
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2010.23.253 　
脳動脈瘤内の血流を低下させるためのステントストラットの探索結果

中山敏男, JEONG Shinkyu, KARKENAHALLI Srinivas, 太田信

バイオエンジニアリング講演会講演論文集　22nd　334　2010/01/08

ISSN：1348-2920
血管バイオモデルを用いたPIVによる瘤内コイル周りの血流解析

太田信, 野田茂穂, 深作和明, 姫野龍太郎, 松本薫

日本バイオレオロジー学会年会プログラム・抄録集　33rd　2010
ブドウ球菌の2成分性毒素γヘモリジンが形成するヘテロヘプタマー膜孔複合体の立体構築とサブユニット間配置の定量的解析

冨田典子, 安西眸, 阿部和代, 金子淳, 神尾好是, 太田信

日本農芸化学会大会講演要旨集　2010　2010
0211 Mechanical Analysis of Blood Vessel Biomodeling Wall Made of Poly (vinyl alcohol) Hydrogel

KOSUKEGAWA Hiroyuki, SHIDA Shuya, HASHIDA Yoko, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2009　(0)　20-20　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2009.22.20 　
0839 Finding stent strut position for reduction of blood flow in cerebral arterial aneurysm

NAKAYAMA Tsoshio, JEONG Shinkyu, KARKENAHALLI Srinivas, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2009　(0)　334-334　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2009.22.334 　
Development of Blood-Mimicking Fluid for Particle Image Velocimetry of Flow in Vascular Biomodel

Shida Shuya, Kosukegawa Hiroyuki, Hashida Yoko, Ohta Makoto

日本流体力学会年会講演論文集　2010　217-217　2010
Publisher: 日本流体力学会

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An in-vitro work fluid to apply to Poly (vinyl alcohol) hydrogel (PVA) model integrated in a circulation system are developed using glycerol. The index of refraction of the fluid is matched to that of PVA model and the model is connected to the circulation system with a pulsatile pump. The viscosity can also be changeable for matching the blood. Since the compliance of PVA model is similar to the arterial wall, the circulation system with PVA model will be helpful for comparison of flow dynamics in rigid wall or for evaluation of medical devices such as stent or coil touching on the artery. These topics are also strong relationship with the rupture of cerebral aneurysm that usually causes subarachnoidal hemorrhage (SAH) and sever morbidity.
197 Measurement of the Thickness of Poly (vinyl alcohol) Hydrogel Biomodel

KIYOMITSU Chihaya, KOSUKEGAWA Hiroyuki, HASHIDA Yoko, OHTA Makoto

The Proceedings of Conference of Tohoku Branch　2010　(0)　194-195　2010
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2010.45.194 　
脳動脈瘤コイル塞栓後の血流変化の計算機流体力学による評価

深作和明, 根来真, 野田茂穂, 松本薫, 太田信, 奈良一成, 高木周, 姫野龍太郎

J Neuroendovascular Ther　3　(4)　263　2009/11/01

ISSN：1882-4072
コイルを留置させた脳動脈瘤モデルでの血流の定量的測定法の開発

松本薫, 野田茂穂, 深作和明, 姫野龍太郎, 太田信

J Neuroendovascular Ther　3　(4)　257　2009/11/01

ISSN：1882-4072
3D visualization of numerical simulation of blood flow on intracranial stent

安西眸, 竹島由里子, 中山敏男, 太田信

日本機械学会年次大会講演論文集　2009　(Vol.6)　177-178　2009/09/12
Hemodynamic studies of coiling in cerebral aneurysm model

松本薫, 野田茂穂, 深作和明, 姫野龍太郎, 太田信

日本機械学会年次大会講演論文集　2009　(Vol.6)　171-172　2009/09/12
ステントストラット配置が脳動脈瘤モデル内の流れに与える影響

奥野健二郎, 中山敏男, RUEFENACHT Daniel A, 太田信

バイオエンジニアリング講演会講演論文集　21st　61-62　2009/01/22

ISSN：1348-2920
脳動脈瘤内の血流減少における最適な箇所の探索

中山敏男, JEONG Shinkyu, KARKENAHALLI Srinivas, RUEFENACHT Daniel A, 高橋明, 太田信

バイオエンジニアリング講演会講演論文集　21st　63-64　2009/01/22

ISSN：1348-2920
ブドウ球菌の2成分性毒素γヘモリジンが形成するヘテロヘプタマー膜孔複合体の立体構造解析

冨田典子, 安西眸, 金子淳, 神尾好是, 太田信

日本ブドウ球菌研究会プログラム・講演要旨集　54th　2009
J0203-1-2 Hemodynamic studies of coiling in cerebral aneurysm model

MATSUMOTO Kaoru, NODA Shigeho, FUKASAKU Kazuaki, HIMENO Ryutaro, OHTA Makoto

The proceedings of the JSME annual meeting　2009　(0)　171-172　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2009.6.0_171 　

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The coil embolization for cerebral aneurysm is one of the effective treatments. However, sometimes blood flow may induce recanalization or growth of the aneurysm. Therefore, the measurements of flow speed with coils in aneurysm are necessary for analyzing the effect of coil on the flow in the aneurysm. However, the method for quantitative measurement using an optical image based velocimetry such as PIV has not been established because coil makes shades in flow field. In this study, we tried to identify the shades by coils and the traces by particles by superimposing consecutive images. Several parts of coils are placed on out of aneurysm cavity and it placement may induce that the speed in inflow zone with coils is larger than that of no coil model. These results will clarify the relationship between coil formation at the neck and the flow in aneurysm.
206 Effect of stent strut position of flow pattern in an ideal cerebral aneurysm model

OKUNO Kenjiro, NAKAYAMA Toshio, RUFENACHT Daniel A., OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2008　(0)　61-62　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2008.21.61 　
207 Search of Most Decreasing Position of Blood Flow Speed in Aneurysm

NAKAYAMA Toshio, JEONGS Shinkyu, KARKENAHALLI Srinivas, RUFENACHT Daniel A., TAKAHASHI Akira, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2008　(0)　63-64　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2008.21.63 　
327 Evaluation of Mechanical Properties of Poly (vinyl alcohol) Hydrogel for the Development of Blood Vessel Biomodeling

KOSUKEGAWA Hiroyuki, MAMADA Keisuke, LIU Lei, KUROKI Kanju, INOUE Kosuke, HAYASE Toshiyuki, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2008　(0)　355-356　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2008.21.355 　
428 Development of Oral Mucosa Model Using Poly (Vinyl Alcohol) Hydrogel

MAMADA Keisuke, KOSUKEGAWA Hiroyuki, FRIDRICI Vincent, OIKAWA Naoto, KATAKURA Yuji, SHIBATA Yukihiko, KUROKI Kanju, OHTA Makoto

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2008　(0)　389-390　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2008.21.389 　
J0203-1-5 3D visualization of numerical simulation of blood flow on intracranial stent

ANZAI Hitomi, TAKESHIMA Yuriko, NAKAYAMA Toshio, OHTA Makoto

The proceedings of the JSME annual meeting　2009　(0)　177-178　2009
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2009.6.0_177 　

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The effect of stent on the flow reduction in cerebral aneurysm has been reported in CFD studies showing the stent position or the strut shape may affect the flow reduction. The 3D visualization may help easily to specify the inlet zone from parent artery to aneurysm and to find the relationship between the effective strut position and the flow pattern. Then we simulated adding a strut to a stent model on the inlet zone after specifying the zone using 3D visualization system. After moving the strut and repeating the visualization of results, we found a strut on the zone may reduce the flow into aneurysm effectively. The results may suggest the 3D visualization is useful for the assessment of strut position with effective reduction of flow into aneurysm.
803 Blood Flow Analysis of a Before-and-after CAS operation for Carotid Stenosis

MORI Futoshi, KAYANO Shingo, TAKAHASHI Akira, OHTA Makoto, MATSUZAWA Teruo

The Computational Mechanics Conference　2008　(21)　325-326　2008/11/01
Publisher: The Japan Society of Mechanical Engineers
ISSN：1348-026X
脳動脈瘤用ステントの血流減少効果を解析するために

太田信

日本機械学会誌　111　(1075)　538-538　2008/06
Development of a catheter and guidewire simulator for interventional therapy

TAKASHIMA Kazuto, OTA Shinzo, OHTA Makoto, YOSHINAKA Kiyoshi, MUKAI Toshiharu

Journal of Japanese Society of Biorheology　22　(1)　12-18　2008/03/25
Publisher: JAPANESE SOCIETY OF BIORHEOLOGY
DOI： 10.11262/jpnbr1987.22.1_12 　

ISSN：0913-4778

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We have developed a catheter and guidewire simulator for interventional therapy. This system was developed to predict the course of approach to a lesion and to present numerical results and animation for surgical planning, intra-operative assistance, the analysis of the structure of the guidewire and the design of a new guidewire. The model of the guidewire is constructed with viscoelastic springs and segments as the dynamic deformation of a flexible structure. The proximal part of the guidewire is inserted into the catheter model. The vessel is an elastic circular cylinder, whose shape is defined by the centerline and the radii. Collisions between the guidewire and the vessel are calculated and the contact forces are determined according to the stiffness and friction of the vessel wall. In this article, we introduce our simulator and several examples of the simulation results.
企業とのwin-win共同研究によるPVAハイドロゲル外科手術練習用口腔粘膜模型の開発

太田信

歯科技工　36　(3)　316-318　2008/03
歯科技工技術と新材料の融合により生体の触感・質感・形状に近づく外科手術練習用口腔模型(口腔粘膜＆骨模型)の開発―医療分野における歯科技工技術応用の可能性拡大の模索から

及川直人, 片倉裕司, 柴田幸彦, 太田信

歯科技工　36　(3)　305-315　2008/03
脳動脈瘤ネットにおけるステントストラットパターンと瘤内の血行動態に関する研究

中山敏男, 太田信, RUEFENACHT Daniel A, 高橋明

バイオエンジニアリング講演会講演論文集　20th　33-34　2008/01/24

ISSN：1348-2920
頸部内頸動脈狭窄症におけるCEAとCAS術後の医用画像を用いた患者特異的モデルと仮想モデルの流体力学シミュレーション

早瀬仁志, 中山敏男, 徳永浩司, 杉生憲志, 西田あゆみ, 有光帥二, 菱川朋人, 小野成紀, 太田信, 伊達勲

日本脳神経外科学会総会抄録集(CD-ROM)　67th　2008

ISSN：1347-9040
脳動脈瘤用ステントの血流減少効果を解析するために(トピックス)

太田信

日本機械学会誌　111　(1075)　538-538　2008
Publisher: 一般社団法人日本機械学会
DOI： 10.1299/jsmemag.111.1075_538 　

ISSN：0021-4728

eISSN：2424-2675
117 Study on Stent Strut Pattern in Neck and Hemodynamics in Cerebral Aneurysm

NAKAYAMA Toshio, OHTA Makoto, RUFENACHT Daniel A., TAKAHASHI Akira

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2007　(0)　33-34　2008
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2007.20.33 　
701 Effect of each stent strut on the hemodynamics in cerebral aneurysm

NAKAYAMA Toshio, OHTA Makoto, RUFENACHT Daniel A., TAKAHASHI Akira

The proceedings of the JSME annual meeting　2008　(0)　17-18　2008
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2008.6.0_17 　

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In this research, we report the effect of each stent strut in aneurysm neck on hemodynamics using the computational fluid dynamics (CFD). The stent strut that deleted a part of it was constructed and that stent was stenting in aneurysm neck, CFD was performed using its shape. By comparing the results of removal stent strut case, the normal stenting case, and the no stenting case, the effect on hemodynamics by each stent strut was researched. From the results, we showed the wall shear stress distribution's greatly changing.
B408 Fabrication of Anisotropic Vessel Model Using PVA-H and Mesh Materials

LIU Lei, KOSUKEGAWA Hiroyuki, OHTA Makoto, HAYASE Toshiyuki

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2008　(0)　145-146　2008
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2008.19.145 　

ISSN：1348-2939
128 Development of oral mucosal model using Poly (vinyl alcohol) gel and paired comparison evaluation of the mechanical properties

MAMADA Keisuke, KOSUKEGAWA Hiroyuki, YAMAGUCHI Koji, OIKAWA Naoto, KATAKURA Yuji, SHIBATA Yukihiko, KUROKI Kanju, OHTA Makoto

The Proceedings of Conference of Tohoku Branch　2008　(0)　57-58　2008
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2008.43.57 　
Blood Flow Analysis of a Before-and-after CAS operation for Carotid Stenosis

MORI Futoshi, KAYANO Shingo, TAKAHASHI Akira, OHTA Makoto, MATSUZAWA Teruo

日本流体力学会年会講演論文集　2008　408-408　2008
Publisher: 日本流体力学会

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The carotid artery is a part to which arteriosclerosis is done easily most in the artery of the whole body. There is stent treatment as a treatment method of this disease. The stent treatment is a less-invasive therapy for Carotid Artery Stenosis (CAS). There are various stent research, however, dynamics factor i.e., the influence of the change in the blood flow and Wall Shear Stress (WSS) which may express the possibility of thrombus growth after stent treatment have not been clarified. In this research, we pay attentions to stent expand aspect because the different of stent expand aspect concerned with a new disease. And reconstructed a before-and-after carotid artery and analyzed it.
803 Blood Flow Analysis of a Before-and-after CAS operation for Carotid Stenosis

MORI Futoshi, KAYANO Shingo, TAKAHASHI Akira, OHTA Makoto, MATSUZAWA Teruo

The Proceedings of The Computational Mechanics Conference　21st　(0)　325-326　2008
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmecmd.2008.21.325 　

ISSN：2424-2799
Development of oral mucosa and bone models for surgical training simulation

及川直人, 柴田幸彦, 片倉裕司, 山口晃史, 熱海啓一, 熊谷康宏, 太田信

日本歯科技工学会雑誌　28　(2)　268-268　2007/12/20

ISSN：0914-7713
ステントによる脳動脈瘤内血流の減少シミュレーション

太田信, 小助川博之, 間々田圭祐, 奥野健二郎, 黒木完樹, 中山敏男

日本バイオマテリアル学会大会予稿集　29th　55　2007/11/26
ネックにおけるステントデザインがおよぼす脳動脈瘤内の血行動態への影響

中山敏男, 太田信, 奥野健二郎, 高橋明, ダニエルルフナハト

J Neuroendovascular Ther　1　(2)　140　2007/11/01

ISSN：1882-4072
Development of oral mucosa and bone models for surgical training simulation

OIKAWA N, SHIBATA Y, KATAKURA Y, YAMAGUCHI K, ATSUMI K, KUMAGAI Y, OHTA M

日本歯科技工学会学術大会 : プログラム : 講演内容抄録　29　51-51　2007/09/22
力学特性を付与した脳動脈瘤モデル開発のためのPoly(vinyl alcohol)hydro‐gelの物性評価

小助川博之, 間々田圭祐, 劉磊, 黒木完樹, 早瀬敏幸, 太田信

日本バイオレオロジー学会年会プログラム・抄録集　30th　69　2007/06/06
実形状ステントを設置した脳動脈瘤内の血流シミュレーション

中山敏男, 太田信, RUEFENACHT Daniel A, 高橋明

バイオエンジニアリング講演会講演論文集　19th　84-85　2007/01/06

ISSN：1348-2920
頸部内頸動脈狭窄症におけるCEAとCASの術前後の3D-CTA,3D-DSA画像を使った生体力学シミュレーション

早瀬仁志, 徳永浩司, 中山敏男, 西田あゆみ, 杉生憲志, 小野成紀, 小野田惠介, 太田信, 伊達勲

日本脳神経外科学会総会抄録集(CD-ROM)　66th　2007

ISSN：1347-9040
Development of Computer-Based Simulator for Catheter Navigation in Blood Vessels (2nd Report, Evaluation of Torquability of Guidewire):2nd Report, Evaluation of Torquability of Guidewire

TAKASHIMA Kazuto, OTA Shinzo, OHTA Makoto, YOSHINAKA Kiyoshi, MUKAI Toshiharu

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C　73　(735)　2988-2995　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaic.73.2988 　

ISSN：0387-5024

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We have developed catheter simulation system in blood vessels for surgical planning and intraoperative assistance. In this study, we evaluated the torquability of the guidewire model for the simulation system. The model of the guidewire is constructed with viscoelastic springs and segments as the dynamic deformation of a flexible structure. The vessel is an elastic circular cylinder, whose shape is defined by the centerline and the radii. Collisions between the guidewire and the vessel are calculated and the contact forces are determined according to the stiffness and friction of the vessel wall. Using these models, the trajectory of the guidewire tip was calculated when the proximal part of the guidewire model was twisted at a constant speed. When the friction coefficient between the guidewire and the vessel is large, the guidewire tip vibrates. When the guidewire is twisted, there is a lag before the guidewire tip starts rotating and friction obstructs this rotation. Besides the friction coefficient, the shape of the blood vessel also affects the motion of the guidewire tip. When the guidewire becomes stiffer, the torquability of guidewire tip increases. This simulator would be useful for the analysis of the structure of the guidewire and may help guide the design of new guidewire.
317 Computational Simulation of Hemodynamics in Cerebral Aneurysm with Geometric Data of a Real Stent

NAKAYAMA Toshio, OHTA Makoto, RUFENACHT Daniel A., TAKAHASHI Akira

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2006　(0)　84-85　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2006.19.84 　
340 Development of linear actuator as a peristaltic motion assist device

Sekine Kazumitsu, Nakazawa Fumio, Shiraishi Yasuyuki, Yambe Tomoyuki, Saijo Yoshifumi, Ohta Makoto, Hori Yoshio, Matsuki Hidetoshi, Sato Fumihiro, Maeda Tsuyoshi

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2006　(0)　336-337　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2006.19.336 　
1128 3-D reconstruction of intracranial artery of rats using micro-CT

OHTA Makoto, NAKAYAMA Toshio, HE Chuan, TAKAHASHI Akira

The proceedings of the JSME annual meeting　2007　(0)　95-96　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2007.6.0_95 　

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The cerebral arteries in rats are reconstructed and the blood flow dynamics are performed by micro-CT for investigating cerebral aneurysms such as mechanism of generation, growing, and rupture of aneurysm. The cerebral arteries in rats were extracted from the brain by using cast techniques. The 3-D reconstruction of arteries by micro-CT indicates the possibilities of computational flow dynamics (CFD). The contrast media was injected from the external carotid artery into the cerebral arteries. The blood flow flushing the contrast media in cerebral arteries observed by micro-CT may allow the trace of blood flow using the cinematic angiography method, if the time resolution increases.
156 Measurement of Frictional Characteristics of Red Blood Cells Moving on the Plates Coated with DLC or MPC Polymer Using Inclined Centrifuge Microscope

KANDORI Takashi, INOUE Kousuke, HAYASE Toshiyuki, TAKAGI Toshiyuki, TAKENO Takanori, OHTA Makoto, TAKEDA Motohiro

The Proceedings of Conference of Tohoku Branch　2007　(0)　111-112　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2007.42.111 　
158 The development of blood flow measurements using the cinematic angiography applied with the optical flow

ONDA Kazuhisa, OHTA Makoto

The Proceedings of Conference of Tohoku Branch　2007　(0)　115-116　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2007.42.115 　
161 Basic Study for Development of Numerical Model of the Pulse Diagnosis

NARUMI Kentarou, NITTA Shin-ichi, NAKANISHI Tsutomu, LIU Lei, SHIRAI Atsushi, HAYASE Toshiyuki, OHTA Makoto, KONNO Satoshi, KAWATA Hiroshi, MARUYAMA Mitsuya

The Proceedings of Conference of Tohoku Branch　2007　(0)　121-122　2007
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmeth.2007.42.121 　
脳動脈瘤内の血流に対するステントデザインの影響

中山敏男, 太田信, RUEFENACHT Daniel A, 高橋明

日本生体医工学会大会プログラム・論文集(CD-ROM)　46th　ROMBUNNO.PS1-6-6　2007
Development of Computer-based Simulator for Catheter Navigation in Blood Vessels : 1st Report, Evaluation of Fundamental Parameters of Guidewire and Blood Vessel

TAKASHIMA Kazuto, OTA Shinzo, OHTA Makoto, YOSHINAKA Kiyoshi, IKEUCHI Ken

Transactions of the Japan Society of Mechanical Engineers C　72　(719)　2137-2145　2006/07/25
Publisher: The Japan Society of Mechanical Engineers
ISSN：0387-5024

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We have developed catheter simulation system in blood vessels for surgical planning and intraoperative assistance. In this study, we evaluated the effect of the fundamental parameters of the guidewire and blood vessel models for the simulation system. The model of the guidewire was constructed with viscoelastic springs and segments to avoid complicated mathematical procedures as the dynamic deformation of a flexible structure. The vessel is an elastic circular cylinder, whose shape is defined by the centerline and the radii. Collisions between the guidewire and the vessel are calculated and the contact forces are determined according to the stiffness, damping and friction of the vessel wall. Using these models, the trajectory of the guidewire tip and the reaction force were calculated. When friction coefficient between the guidewire and the vessel is large, the guidewire tip vibrates. When deformation property of the vessel is changed, the trajectory of guidewire tip also changes. Bending of the guidewire tip decreases the reaction force at bending points of the vessel. When the guidewire becomes stiffer, the deformation of the vessel becomes large. These findings should facilitate determination of the parameters of the simulation system.
Development of Computer-based Simulator for Catheter Navigation in Blood Vessels (1st Report, Evaluation of Fundamental Parameters of Guidewire and Blood Vessel):1st Report, Evaluation of Fundamental Parameters of Guidewire and Blood Vessel

TAKASHIMA Kazuto, OTA Shinzo, OHTA Makoto, YOSHINAKA Kiyoshi, IKEUCHI Ken

TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C　72　(719)　2137-2145　2006
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/kikaic.72.2137 　

ISSN：0387-5024

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We have developed catheter simulation system in blood vessels for surgical planning and intraoperative assistance. In this study, we evaluated the effect of the fundamental parameters of the guidewire and blood vessel models for the simulation system. The model of the guidewire was constructed with viscoelastic springs and segments to avoid complicated mathematical procedures as the dynamic deformation of a flexible structure. The vessel is an elastic circular cylinder, whose shape is defined by the centerline and the radii. Collisions between the guidewire and the vessel are calculated and the contact forces are determined according to the stiffness, damping and friction of the vessel wall. Using these models, the trajectory of the guidewire tip and the reaction force were calculated. When friction coefficient between the guidewire and the vessel is large, the guidewire tip vibrates. When deformation property of the vessel is changed, the trajectory of guidewire tip also changes. Bending of the guidewire tip decreases the reaction force at bending points of the vessel. When the guidewire becomes stiffer, the deformation of the vessel becomes large. These findings should facilitate determination of the parameters of the simulation system.
528 Fundamental study on catheter simulator for intravascular surgery

TAKASHIMA Kazuto, OTA Shinzo, OHTA Makoto, YOSHINAKA Kiyoshi, IKEUCHI Ken

The Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME　2005　(0)　355-356　2006
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebio.2005.18.355 　
B105 Fundamental study on catheter simulator for intravascular surgery : 2nd report, evaluation of calculation method of contact force

TAKASHIMA Kazuto, OTA Shinzo, OHTA Makoto, YOSHINAKA Kiyoshi, MUKAI Toshiharu

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2006　(0)　49-50　2006
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2006.17.49 　

ISSN：1348-2939
B108 Development and Experimental Validation of Mathematical Model for Acquisition of Information in Pulse Diagnosis

NARUMI Kentarou, SHIRAISHI Mitsuya, NITTA Shin-ichi, NAKANISHI Tsutomu, LIU Lei, INOUE Kosuke, SHIRAI Atsushi, HAYASE Toshiyuki, OHTA Makoto, KONNO Satoshi, KAWATA Hiroshi

The Proceedings of the JSME Conference on Frontiers in Bioengineering　2006　(0)　55-56　2006
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmebiofro.2006.17.55 　

ISSN：1348-2939
822 Three Dimensional Geometry Measurements of Cerebral Aneurysms and Vessel Sizes for Analytical Geometry(1)

OHTA Makoto, RUFENACHT Daniel A.

The Proceedings of the Fluids engineering conference　2006　(0)　_822-a_　2006
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmefed.2006._822-a_ 　

ISSN：1348-2882
822 Three Dimensional Geometry Measurements of Cerebral Aneurysms and Vessel Sizes for Analytical Geometry(2)

OHTA Makoto, RUFENACHT Daniel A.

The Proceedings of the Fluids engineering conference　2006　(0)　_822-1_-_822-4_　2006
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmefed.2006._822-1_ 　

ISSN：1348-2882

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Our goal is to find the range of size of cerebral aneurysms, neck sizes, and vessel diameters based on a 3D rotational angiography (3D-RA). Measurement of 1st (A), 2nd, and 3rd axes of aneurismal cavity, the maximum and the minimum diameter of neck (N), and the diameter of parent vessel (P) were obtained from 43 cerebral aneurysms in 33 patients with use of 3D-RA (Philips Medical Systems). The most frequent place where cerebral aneurysms were found in the 43 is ICA (9) and AcomA (9). The long diameter of neck is the almost same as the short one or 1.75-fold longer than that of shorter neck. The form of aneurysm cavity was an ellipsoid which allowed calculating the volume with the three axes. The 1st axis is 0.77-fold longer than the 2nd axis and is 0.70-fold longer than the 3rd length.
1307 Numerical Experiment and Experimental Application of Ultrasonic-Measurement Integrated-Simulation with PVA Straight Pipe Model(2)

LIU Lei, INOUE Kosuke, HAYASE Toshiyuki, OHTA Makoto

The Proceedings of the Fluids engineering conference　2006　(0)　_1307-1_-_1307-4_　2006
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmefed.2006._1307-1_ 　

ISSN：1348-2882

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Thoracic aortic dissection has a high fatality rate, and the number of fatalities has tendency to increase with advancing age. Because of our fast-aging society, it is a problem calling for immediate solution. It is difficult to recognize the exact structure of the 3D blood flow with measurement existing. Besides, because we cannot set precise boundary condition of living body, computer simulation is not a complete tool to analyze real blood flows. Our research group had propounded a new solution, integrating together ultrasonic-measurement and CFD to investigate blood flows, which is called Ultrasonic-Measurement-Integrated (UMI) Simulation. Usability of UMI simulation has been confirmed by numerical experiment in former studies. In this report, experimental system consisting of a PVA hydro-gel straight pipe model and constant head flow tank was developed, and fundamental experiment to confirm the performance of the ultrasound measurement device was performed. In parallel with experiment, a numerical experiment with axisymmetric straight pipe model was performed. In this report, we confirmed characteristics of the ultrasound measurement to the PVA model in experiment and usability of the UMI simulation in numerical experiment.
Three Dimensional Geometry Measurements of Cerebral Aneurysms and Vessel Sizes for Analytical Geometry

太田信, RUEFENACHT Daniel A

日本機械学会流体工学部門講演会講演論文集(CD-ROM)　84th　ROMBUNNO.822　2006

ISSN：1348-2882
The role of engineering for treatments

Makoto OHTA

Sendaishi ishikai kaiho　497　3-7　2005/11
Publisher: Sendai shi Ishikai
モデルを用いた,脳動脈瘤内の血流変化におけるステントの影響

太田信, 藤村直子, AUGSBURGER Luca, WETZEL Stephan, YILMAZ Hasan, ABDO German, LOVBLOD Karl‐Olof, BARATH Krisztina, RUEFENACHT Daniel A

日本流体力学会年会講演論文集　2005　224　2005/09/05

ISSN：1342-8004
Aim to an engineering with facing to treatments

Makoto OHTA

Manabino mori　32　(Summer)　4-5　2005/06/30
Publisher: Tohoku Univ.
1107 Development of Flow Speed in Cerebral Aneurysm by using Cinematic Angiography

OHTA Makoto, FUJIMURA Naoko, IWATA Hiroo, TSUTSUMI Sadami, RUFENACHT Daniel A.

The proceedings of the JSME annual meeting　2005　(0)　87-88　2005
Publisher: The Japan Society of Mechanical Engineers
DOI： 10.1299/jsmemecjo.2005.5.0_87 　

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Image guided minimally invasive treatments for cerebral aneurysms have been popular for last decade. The implantation such as coil or stent reduces the flow in the cavity and the cinematic angiography (CA) has a potentiality for measuring the flow speed during a treatment. In this paper, we applied the CA with 25f/s to a real cerebral aneurysm to take successive images and measured the flow speed in the cavity. Two usual angles of Posteroanterior (PA) and Lateral (LA) projections were selected and images are taken simultaneously. The condition of CA was 60kV and 300mA. The left-convolution flow was observed form the viewpoint of PA and around 50mm/s. The inflow from the parent artery was rotated with the counterclockwise in the aneurysm. The speed of inflow was 359mm/s and reduced in the cavity. The CA is possible to measure the flow speed in aneurysm.
AM05-17-008 Imapct of stent on blood flow in a model of cerebral aneurysm

OHTA Makoto, FUJIMURA Naoko, AUGSBURGER Luca, WETZEL Stephan, YILMAZ Hasan, ABDO German, LOVBLOD Karl-Olof, BARATH Krisztina, RUEFENACHT Daniel A.

日本流体力学会年会講演論文集　2005　224-224　2005
Publisher: 日本流体力学会

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Endovascular stent implantation is used for treating cerebral aneurysms by reducing flow in the cavity and the evaluation of stent will be performed by measurements of flow speed. The impact of stent on the blood flow may depend on the design of stent strut. In this study, two stents (Stent A has larger slit and bigger diameter of the strut than Stent B) with similar geometries were prepared. The inflow zone was created at the distal neck and the zone of Stent B included the stent struts, whereas the inflow zone of Stent A was in their two struts. The flow speed measured by SVC method exhibits the speed of stent B was decreased, while that of Stent A was higher than no stent. The capability of the stent for reducing flow into the cavity will depend on the strut diameter and the opened cell on the inflow zone.
AM05-17-011 Experimental Apparatus to Simulate Blood Flow in Aorta for Validation of Ultrasonic-Measurement-Integrated Simulation

LIU Lei, Inoue KOSUKE, HAYASE Toshiyuki, OHTA Makoto

日本流体力学会年会講演論文集　2005　227-227　2005
Publisher: 日本流体力学会

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Thoracic aortic dissection has a high fatality rate, and the number of fatalities is tendency to increase with advancing age. Because of our fast-aging society, it's a problem calling for immediate solution. It's difficult to recognize the exact structure of the 3D blood flow with measurement existing, and that makes having an elucidation of mechanism adversity. Our research group had propounded a new solution; integrate together ultrasonic-measurement and CFD to investigate blood flow, which is called Ultrasonic-Measurement-Integrated (UMI) Simulation. Usability of UMI simulation has been confirmed by numerical experiment in former studies. In this paper,_<in-vitro> system for fluid flow experiment to verify UMI simulation was fabricated and pilot study was performed. Thoracic aneurysm models in this system, based on CT scan data and duplicated its original configuration precisely, were made of Silicone rubber and PVA-polymer. The letter models has elasticity like real vessels is a point worthy of special mention.
28aWD-1 Analysis of stent characteristics in saccular-cerebral-aneurysm flows

Hirabayashi Miki, Ohta Makoto, Rufenacht Daniel A., Chopard Bastien

Meeting Abstracts of the Physical Society of Japan　59　(0)　282-282　2004
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.59.1.2.0_282_3 　

ISSN：1342-8349
Numerical analysis of flow reduction mechanism of stented saccular cerebrai aneurysms

Hirabayashi Miki, Ohta Makoto, Rufenacht Daniel A., Bastien Chopard

Meeting Abstracts of the Physical Society of Japan　58　(0)　277-277　2003
Publisher: The Physical Society of Japan
DOI： 10.11316/jpsgaiyo.58.1.2.0_277_1 　

ISSN：1342-8349
Wear Properties and Mechanical Properties of Slightly Cross-Linked Ultra-High Molecular Weight Polyethylene Crystallized under Uniaxial Compression(Special Issue on Polymer Materials)

OHTA Makoto, Suong-Hyu HYON, Yu-Bong KANG, OKA Masanori, TSUTSUMI Sadami, MURAKAMI Syozo, KOHJIYA Shinzo

Journal of the Society of Materials Science, Japan　49　(12)　1301-1305　2000/12/15
Publisher: The Society of Materials Science, Japan
ISSN：0514-5163

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In order to improve the wear properties of artificial joints, a slightly cross-linked ultra high molecular weight polyethylene(UHMWPE)was compressed at molten state and crystallized by cooling to room temperature. The molecular chain of the UHMWPE was orientated to the direction of deformation.Density and melting point of the mold article were increasd in accordance with compression ratio.The α_c peak of loss modulus was shifted to higher temperature compared with the non-compressed sample.And it was also revealed that the weight loss of the compressed UHMWPE was remarkably less than that of a non-compressed sample from the result of the pin-on-disc wear test.
Measurement of Tissues Elastic Modulus Using MR Elastography

SUGA Mikio, OSHIRO Osamu, MINATO Kotaro, MATSUDA Tetsuya, TAKAHASHI Takashi, OHTA Makoto, TSUTSUMI Sadami, OKAMOTO Jun, TAKIZAWA Osamu

医療情報学連合大会論文集　20　532-533　2000/11/23
Motion Analysis of Mandible with Turbo-FLASH MR Imaging System

AZUMA Takashi

日本臨床バイオメカニクス学会誌 = Proceedings of ... Annual Meeting of Japanese Society for Clinical Biomechanics and Related Research　21　489-496　2000/10/01

ISSN：1340-9018
Measurement and Evaluation of Elastic Modulus Using MR Elastography

SUGA Mikio, OSHIRO Osamu, MINATIO Kotaro, MATSUDA Tetsuya, OHTA Makoto, TSUTSUMI Sadami, TAKAHASHI Takashi, OKAMOTO Jun, TAKIZAWA Osamu

Med Imag Tech　18　(4)　385-386　2000/07/25

ISSN：0288-450X
DEVELOPMENT AND MEASUREMENTS OF ELASTIC MODULI WITH PVA GELS AS STANDARD MATERIALS FOR SOFT TISSUES

OHTA Makoto, TSUDA Yuko, AZUMA Takashi, NAMBU Toshiyuki, HYON Suong-Hyu, TSUTSUMI Sadami, IMAI Maki, KOMORI Masaru, MATSUDA Tetsuya, TAKHASHI Takashi, SUGA Mikio, MINATO Kotaro

Medical Imaging Technology　18　(4)　393-394　2000/07/25

ISSN：0288-450X
A MEASUREMENT SYSTEM EMPLOYING LOW FREQUENCY RESONANCE METHOD FOR VISCO-ELASTICITY OF SOFY LIVING TISSUES

MINOURA Tetsuji, SAKAI Nobuyuki, NAGATA Izumi, OHTA Makoto, TSUDA Yuko, TSUTSUMI Sadami

Medical imaging technology　18　(4)　395-396　2000/07/25

ISSN：0288-450X
"MREを用いた剛性率と粘性率の計測",Medical Imaging Technology Peer-reviewed

大城理, 菅幹生, 太田信, 松田哲也, 堤定美, 湊小太郎, 千原國宏, 高橋隆

1998
Improvement of Wald's method for detection of weak ultrasonic echo signal

OHTA Makoto, NISIMURA Eizo, TSUTSUMI Sadami

IEICE technical report. Ultrasonics　96　(320)　53-58　1996/10/22
Publisher: The Institute of Electronics, Information and Communication Engineers

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We improved the conventional Wald's method which has two thresholds so that it is known to be effective for weak ultrasonic echo signals. We employed a new algorithm in which the signals are successively added and divided until the detection ratio becomes 1. Thus, we could significantly reduce the number of observations and found that the improved method works well when the S/N ratio is higher than 5.5db.
3)仮想現実感技術を応用した教育用シミュレータの開発 : 歯科臨床における医療技術伝承のための試み(ヒューマンインフォメーション研究会)

南部敏之, 阿部昌代, 太田信, 西村営三, 提定美

テレビジョン学会誌　50　(2)　319-319　1996/02/20
Publisher: 一般社団法人映像情報メディア学会
ISSN：0386-6831
Computer-aided-instruction by virtual reality in clinical dentistry : Virtual reality simulator for practical training in clinical dentistry

Nambu Toshiyuki, Abe Masayo, Ohta Makoto, Nishimura Eizo, Tsutsumi Sadami

ITE Technical Report　19　(47)　13-18　1995
Publisher: The Institute of Image Information and Television Engineers
DOI： 10.11485/tvtr.19.47_13 　

ISSN：0386-4227

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In this age of advanced and complicated clinical dentistry, knowledge acquisition through books and training methods using mannikins cannot provide adequate training results. With Virtual Reality (VR) system, our approach is to develop a "therapeutic simulator" whereby the skill of remedy of expert dentists can be inherited intuitively by dental trainees. The digitizer has 7 links with 7 degrees of freedom like the human arm, and an electric rotary encoder was set to evaluate the movement of the handpiece with accuracy better than 0.5mm. The application of virtual reality provides the advantages of 1) supplementing intermediate and mannikin-based training in the process of practical education, 2) enables training in abnormal cases as when the patient's tongue moves suddenly, and 3) enables three-dimensional recording of the process of tooth cutting, which can be played back later for review. This study was supported by the Grant-in-Aid for Scientific Research from the Ministry of Education, Science and Culture in Japan (No. (A) (1) 05507004).

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Books and Other Publications 5

New trend of Intervention

Ohta, M, Tsutsumi S, Rüfenacht DA

Institute of advanced treatment and technology　2004/09
Safety and Bio compatibility of Bio materials and Medical devices

Ohta M, Handa A, Rüfenacht D, Tsutsumi S

CMC publisher　2003/11/28
Computational Science-ICCS

M. Hirabayashi, M. Ohta, D. A. Ruefenacht, B. Chopard

P.M.A　2003/01
Joint Arthroplasty

M. Oka, S.-H. Hyon, Makoto Ohta, T. Nakamura, Y. Ushio, J.Toguchida

Springer-Verlag Tokyo　1999/01
Adv. in Polym. Biomate. Sci

Suong-Hyu Hyon, Makoto Ohta, Masanori Oka, Sadami Tsutsumi

1997/01

Presentations 381

超音波検査用バイオモデル材料のPVA-H 3Dプリンタへの応用

小池隼太, Shiddiq Hashuro, 小林直裕, Simon Tupin, 小助川博之, 戸塚厚, 太田信

日本機械学会東北支部第56期総会・講演会　2021/03/12
脳血管確率アトラスに基づく脳血管自動ラベル付けプログラムの開発（第１報、中心線に基づく確率アトラスのラベル付け精度の評価）

神容慶, 北村洸, 太田信, 安西眸, 麦倉俊司, 森菜緒子

第54回日本生体医工学会東北支部大会,　2021/01/23
Optimization of stent structure based on blood flow simulation Invited

Hitomi Anzai, Mingzi Zhang, Narendra Kurnia Putra, Makoto Ohta

2ND INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL BIOFLUID 2020　2020/12/16
CFD analysis of AVF for hemodialysis

Kazuki Takeda, Hitomi Anzai, Mingzi Zhang, Kohei Mitsuzuka, Wang Haoran, Ai Kajiyama, Makoto Ohta

2ND INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL BIOFLUID 2020　2020/12/16
The influence brought by specific boundary conditions on vascular simulations

Fangjia Pan, Makoto Ohta, Hitomi Anzai, Shunji Mugikura, Naoko Mori

2ND INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL BIOFLUID 2020　2020/12/16
WSS and Frequency Characteristics in Patient-Specific Aneurysm in MCA

Ryuhei Yamaguchi, Tomoaki Yamazaki, Nadia Shaira Shafii, Gaku Tanaka, Makoto Ohta

2ND INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL BIOFLUID 2020　2020/12/16
A study on Optical Flow Method for Hemodynamics Estimation

Yutaro Kohata, Hitomi Anzai, Makoto Ohta, Meghane Decroocq, Carole Frindel, Simon RIT

2ND INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL BIOFLUID 2020　2020/12/16
One way characteristics in Patient Specific Aneurysm in MCA

Nadia Shaira Shafii, Ryuhei Yamaguchi, Ahmad Zahran, Md Khudzari, Makoto Ohta, Kahar Osman

2ND INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL BIOFLUID 2020　2020/12/16
Flow characteristics in Full-scale Patient Specific Aneurysm in Basilar Artery

Tomoaki Yamazaki, Ryuhei Yamaguchi, Gaku Tanaka, Makoto Ohta

2020/12/16
血管内治療デバイス留置シミュレータの開発 (デバイスパラメータの影響)

太田寛人, 高嶋一登, 芳賀洋一, 戴晨鳴, 太田信, 庄島正明

日本機械学会第31回バイオフロンティア講演会
Development and Eveluation of PVA-H 3D Printed Blood Vessel Biomodels with Several Stiffness

Naohiro Kobayashi, Ryota Nagano, Makoto Ito, Yasutomo Shimizu, Simon Tupin, Makoto Ohta

International Mechanical Engineering Congress and Exposition IMECE2020
Implementation of Computer Simulation to Assess Flow−Diversion Treatment Outcomes— Systematic Review and Meta−Analysis Invited

Mingzi Zhang, Simon Tupin, Hitomi Anzai, Yutaro Kohata, Massaki Shojima, Kosuke Suzuki, Yoshihiro Okamoto, Katsuhiro Tanaka, Takanobu Yagi, Soichiro Fujimura, Makoto Ohta
CFD Analysis of The Effect of Flush Flow Condition on Angiopscopy Visibility

Kohei Mitsuzuka, Yujie Li, Toshio Nakayama, Hitomi Anzai, Wang Haoran, Makoto Ohta, Simon Tupin

17th International Conference on Flow Dynamics,
Permeability-Microstructure Relationship in Cancellous Bone

Simon Tupin, Makoto Ito, Makoto Ohta

17th International Conference on Flow Dynamics,
生体組織モデルを用いた医療機器開発へ参加のお誘い Invited

太田信, Tupin Simon, 安西眸, 于凱鴻, Zhang Mingzi, 戸塚厚, 小助川博之

第61回日本脈管学会総会
Implementation of Computer Simulation to Assess Flow−Diversion Treatment Outcomes — Systematic Review and Meta−Analysis Invited

Mingzi Zhang, Simon Tupin, Hitomi Anzai, Yutaro Kohata, Massaki Shojima, Kosuke Suzuki, Yoshihiro Okamoto, Katsuhiro Tanaka, Takanobu Yagi, Soichiro Fujimura, Makoto Ohta

CFD-Bio, 日本機械学会バイオエンジニアリング部門制御と情報－生体への応用研究会脳神経血管内治療に関する医工学連携研究会　2020/10/05
Development of Transparent PVA-H Model with Scattering Ability for Ultrasound Usage

Muhammad Shiddiq Sayyid Hashuro, Simon Tupin, Daisuke Goanno, Makoto Ito, Kosuke Inoue, Toshiyuki Hayase, Makoto Ohta

14th International Symposium on Advanced Biomedical Ultrasound 2020　2020/09/23
マイクロセンサを搭載した血管モデル

戴晨鳴, 吉田洋, 松永忠雄, 鶴岡典子, 于凱鴻, 清水康智, 太田信, 庄島正明, 高嶋一登, 原田香奈子, 益田泰輔, 新井史人, 芳賀洋一

生体医工学シンポジウム2020　2020/09/18
(骨)モデルの国際標準を進めるWG14への参加の勧め Invited

太田信

医用立体モデルコンソーシアム 2020年度総会・講演会　2020/07/30
Flow characteristics in a deformable full-scale patient-specific cerebral aneurysm

Gaku Takizawa, Tomohiro Yamazaki, Nadia S. Shafii, Ryuhei Yamaguchi, Gaku Tanaka, Simon Tupin, Shiddiq Hashuro, Kahar Osman, Makoto Ohta

2020 Summer Biomechanics, Bioengineering and Biotransport Conference (SB³C2020)　2020/06/18
Endothelial Cells Distribution on the Stent Strut with Surface Treatment after the Flow Exposure

Zi Wang, Narendra Kurnia Putra, Kako Yamasaki, Naofumi Ohtsu, Hisatoshi Kobayashi, Makoto Ohta
Numerical simulation of flow behavior in basilar bifurcation artery aneurysms based on 4D-CTA

山崎智皓, 岡崎陽大, 田中学, 太田信, 石田藤麿, 山口隆平

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　2020
Behavior of flow in a middle cerebral aneurysm with deformation

池谷直紀, 山崎智皓, 田中学, 太田信, 山口隆平

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　2020
Development of Device Placement Simulator for Endovascular Treatment (Evaluation of Coil Contact Force and Catheter Motion)

大石卓弥, 高嶋一登, 葭中潔, YU Kaihong, 太田信, 森浩二, 当麻直樹

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　2020
Cerebrovascular Model Equipped with Microsensors

芳賀洋一, 芳賀洋一, 吉田洋, 松永忠雄, 清水康智, 太田信, 太田信, 庄島正明, 益田泰輔, Yu Kaihong, Simon Tupin, Dai Chenming, 新井史人, 原田香奈子

電気学会論文誌 E　2020
コイル塞栓術における脳血管内治療医の注視点の特徴と経験症例数との関係

岡本吉弘, 庄島正明, 新妻邦泰, 太田信, 植松美幸, 迫田秀行, 配島由二

人工臓器(日本人工臓器学会)　2020
バイオニックヒューマノイドプラットフォームと要素技術の成果

益田泰輔, 小俣誠二, 相原一, 森田明夫, 金太一, 齊藤延人, 山下樹里, 鎮西清行, 福田敏男, 太田信, 芳賀洋一, 光石衛, 原田香奈子, 新井史人

日本生体医工学会大会プログラム・抄録集(Web)　2019
PARTICLE IMAGE VELOCIMETRY ANALYSIS OF FLUSH FLOW DURING INTRAVASCULAR ENDOSCOPY

三塚康平, TUPIN Simon, LI Yujie, 中山敏男, 太田信

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　2019
Normalization of Basilar Artery Structure with MRA Images

北村洸, 麦倉俊司, 太田信, 安西眸

日本機械学会バイオフロンティア講演会講演論文集(CD-ROM)　2019
脳動脈瘤コイル留置のシミュレーション-目的と課題-

当麻直樹, 高嶋一登, 太田信, 森浩二

脳血管内治療(Web)　2019
脳動脈瘤コイル留置のシミュレーション-手法と応用例-

高嶋一登, 当麻直樹, 太田信, 森浩二

脳血管内治療(Web)　2019
Behavior of flow in patient-specific cerebral aneurysm with wall elasticity

滝澤岳, 田中学, TUPIN Simon, 太田信, 山口隆平

バイオエンジニアリング講演会講演論文集(CD-ROM)　2019
Research on Arterial Stiffness in Type 2 Diabetic Patients Based on Pulse Wave Analysis

Gaoyang Li, Xiaorui Song, Aike Qiao, Makoto Ohta

15th ICFD (Internatinal Conference of Fluid Dynamics　2018/11
Hemodynamic Study on Coronary Artery Aneurysms with Bypass Surgery

Haoran Wang, Hitomi Anzai, Makoto Ohta, Youjun Liu

15th ICFD (Internatinal Conference of Fluid Dynamics)　2018/11
Permeability studies for the improvement of medical devices

Simon Tupin, Makoto Ito, Makoto Ohta

15th ICFD (Internatinal Conference of Fluid Dynamics)　2018/11
Compliance effect on the flow condition in vascular in vitro experiments

Masami Matsuura, Simon Tupin, Makoto Ohta

ASME 2018 International Mechanical Engineering Congress and Exposition　2018/11
3Dプリンタを用いたPVA‐H血管モデル作製用複合機の開発(第一報)

長野凌太, 清水康智, 吉田洋, 松永忠雄, 葛迫淳一, 木原信宏, 芳賀洋一, 芳賀洋一, 太田信, 太田信

日本シミュレーション外科学会会誌　2018/10
バイオニックヒューマノイドの開発と評価

山下樹里, 原田香奈子, 太田信, 鎮西清行

ヒューマンインタフェースシンポジウム論文集(CD-ROM)　2018/09/05
Characteristics of Elasticity on Flow Behavior in Middle Cerebral Aneurysm Model

Ryuhei Yamaguchi, Gaku Tanaka, Taihei Kotani, Kahar Osman, Nadia Shafii, Hitomi Anzai, Makoto Ohta

8th World Congress of Biomechanics　2018/07
Dose hypertension history affect morphology or hemodynamic characteristics of Cerebrobasilar System? Retrospetive study of 249 patients diagnosed with hypertension.

Yujie Li, Mingzi Zhang, Ko Kitamura, Hitomi anzai, Shuji Mugikura, Makoto Ohta

8th World Congress of Biomechanics　2018/07
PIV MEASUREMENT IN AN IDEAL ANEURYSMAL MODEL USING A TRANSPARENT COIL MODEL

Makoto OHTA, Masanori KUZE, Simon TUPIN, Kaihong YU, Yasutomo SHIMIZU, Hitomi ANZAI

Conference on Modelling Fluid Flow (CMFF’18)　2018/07
FBGセンサによる非侵襲多機能バイタルサイン検知原理の解明

ウェアラブルバイタルサイン測定システム開発プロジェクト，第一回公開講演会　2016/12/09
脳血管内治療デバイスと治療の有効性を予測する血管モデルの開発

脳神経血管内治療学会，ものづくりコモンズジョイントシンポジウム　2016/11/26
脳動脈瘤の生化学的イベントと数値流体解析の応用に関するCutting-Edge International-presentation

脳神経血管内治療学会，機械学会バイオエンジニアリング部問共同研究会「脳神経血管内治療に関する医工学連携研究会」，国際頭蓋内ステント学会共同シンポジウム　2016/11/26
In Vitro Experimental Evaluation for Radiofrequency Ablation: Electrode Temperature and Lesion Size of Ablation with Open Irrigation Cooling International-presentation

3rd Biomedical Science and Technology Symposium (Macquarie-Tohoku Symposium)　2016/11/09
BioModels International-presentation

3rd Biomedical Science and Technology Symposium (Macquarie-Tohoku Symposium)　2016/11/05
Modeling of cerebral vascular diseases International-presentation

3rd Biomedical Science and Technology Symposium (Macquarie-Tohoku Symposium)　2016/11/05
Stent Evaluation in vitro: Towards Next Generation of Biomodels International-presentation

3rd Biomedical Science and Technology Symposium (Macquarie-Tohoku Symposium)　2016/11/05
An Investigation on the Effect of Vessel Wall Deformation on Blood Flow and Wall Shear Stress International-presentation

13th International IntraCranial Stent Meeting　2016/11
Blood Flow Into Basilar Tip Aneurysms A Predictor for Recanalization After Coil Embolization International-presentation

13th International IntraCranial Stent Meeting　2016/11
Computer simulation of intracranial stent deployment International-presentation

13th International IntraCranial Stent Meeting　2016/11
Correlating MR Wall Enhancement and Wall Shear Stress: Does CFD work to predict aneurysm instability? International-presentation

13th International IntraCranial Stent Meeting　2016/11
Exploring the relationship between the inflow zone and strut positions within the aneurysm orifice: a hemodynamic simulation study (P35) [ International-presentation

13th International IntraCranial Stent Meeting　2016/11
Haemodynamic Simulation of Aneurysm Treated with Virtual Flow Diverter International-presentation

13th International IntraCranial Stent Meeting　2016/11
Hemodynamic Simulation for Cerebrovascular Stent International-presentation

3rd Biomedical Science and Technology Symposium (Macquarie-Tohoku Symposium)　2016/11
Which Stent Diameter and Compaction Ratio Would Benefit the Patient the Most? A Computer Simulation of Virtual Stent Deployment for Treatment Rehearsal International-presentation

3rd Biomedical Science and Technology Symposium (Macquarie-Tohoku Symposium)　2016/11
Development of an In Vitro Test Platform for the Quantitative Evaluation of Stent Devices and their Deployment International-presentation

Thirteenth International Conference on Flow Dynamics　2016/10/11
Comparison Study of Blood Flow Pattern Changes due to the Blood Vessel Deformation during Intravascular Stent Deployment International-presentation

TFC ELyT Workshop 2016　2016/10
Drilling under constant feed rate for bone biomodel made of acrylic composites International-presentation

TFC ELyT Workshop 2016　2016/10
Evaluation of Tissue Heating for Radiofrequency Ablation Using a Vibrating Catheter International-presentation

TFC ELyT Workshop 2016　2016/10
Hemodynamic Behaviors under Blood Vessel Deformation by Stent Struts: Two Dimensional Study. International-presentation

Thirteenth International Conference on Flow Dynamics　2016/10
In-vitro evaluation of the effect of a multi-layer stent device deployment on the aorta-renal artery bifurcation hemodynamics International-presentation

ElyT workshop 2017　2016/10
Radiofrequency Ablation: Lesion Size Measurement on Agar Phantom International-presentation

TFC ELyT Workshop 2016　2016/10
Introduction of Evaluation of Endoleak in Ink Flow Study

生体医工学シンポジウム2016　2016/09
Material Investigation for the study of drilling bone biomodel International-presentation

3rd International Conference on BioTribology (ICoBT 2016)　2016/09
擬似血液を用いた振動カテールアブレション周りのPIV計測

LIFE2016　2016/09
血管内治療のための血管モデル開発

日本機械学会 2016 年度年次大会　2016/09
流れ中における内皮化促進のための表面処理に関する研究

日本流体力学会年会2016　2016/09
力学的、熱力学的機能性を付与した生体組織モデル（バイオモデル）の開発と応用

第１２回東北大学 REDEEM シンポジウム　2016/09
Introduction of a flow rate and pressure controlled in vitro model to evaluate stent deployment effects to blood flow

東北大学-信州大学共催シンポジウム　2016/08/03
医療デバイス設計のための形状最適化とCFD

第20回流体科学におけるバイオ・医療に関する講演会　2016/06/15
AVEC CFD 2016

第39回日本バイオレオロジー学会年会　2016/06
Development of In-vitro Model for Evaluation of Endoleak and Migration on Stent Graft International-presentation

VII European Congress on Computational Methods in Applied Sciences and Engineering　2016/06
低レイノルズ数領域における血液環流フローチャンバーシステムの開発

第39回日本バイオレオロジー学会年会　2016/06
Distribution on Endothelial Cells Downstream of a Stent Strut: An In-vitro Study International-presentation

VII European Congress on Computational Methods in Applied Sciences and Engineering　2016/05/09
Optimal Interval of two struts relative to aneurysm inflow International-presentation

VII European Congress on Computational Methods in Applied Sciences and Engineering　2016/05/09
Endothelialization on NiTi wire with immobilization of collagen using HMDI International-presentation

10th World Biomaterials Congress　2016/05
Impact of Mechanical Vibration RF Ablation Compared with Conventional RF Ablations International-presentation

Heart Rhythm Society’s 37th Annual Scientific Sessions　2016/05
振動カテーテルを用いてカテーテルアブレーション中の接触力による影響

第53回日本伝熱シンポジウム　2016/05
血管モデルの開発

医工連携セミナー（先端医用機器開発）　2016/03/17
Development of a new catheter for selective venous sampling International-presentation

ECR, 2016]　2016/03
カテーテルアブレーション評価に用いる血液の粘度を考慮した作動流体の開発

機械学会東北支部　2016/03
Material and Surface Design for Medical Application International-presentation

JSPS Core-to-core program, International research core on smart layered materials and structures for energy saving　2016/01/20
ステントグラフトのエンドリークおよびマイグレーション評価用 in-vitro モデルの開発

第28回バイオエンジニアリング講演会　2016/01
せん断応力を負荷した内皮細胞の TGF-β1 が共存培養モデル内平滑筋細胞の形質に与える影響

第28回バイオエンジニアリング講演会　2016/01
動脈瘤ネックの流入領域に対するストラットの相対位置が瘤内流れに与える影響

第28回バイオエンジニアリング講演会　2016/01
非侵襲血圧計測機器開発のための血管モデル

ウェアラブルバイタルサイン測定システム開発プロジェクト特別講演会　2015/12/07
Comparsion of Drilling Behavior of Acrylic Materials Measured by Tribometer International-presentation

Beijing-Tohoku Biomechanics Symposium　2015/11/25
Development of in-vitro and in-silico model for evaluating medical devices International-presentation

Beijing-Tohoku Biomechanics Symposium　2015/11/25
Optimization of Flow Diverter design International-presentation

Beijing-Tohoku Biomechanics Symposium　2015/11/25
Biofluid Control International-presentation

Proceedings of 2nd Biomedical Symposium and 1st Biomedical Engineering Symposium　2015/11/16
Co-relationship between Hemodynamics and Optimal Stent Structure International-presentation

Proceedings of 2nd Biomedical Symposium and 1st Biomedical Engineering Symposium　2015/11/16
Hemodynamics Study with In-Vitro Aneurysm Phantom International-presentation

Proceedings of 2nd Biomedical Symposium and 1st Biomedical Engineering Symposium　2015/11/16
Introduction to Graduate School of Engineering (GSE) at Tohoku University International-presentation

Proceedings of 2nd Biomedical Symposium and 1st Biomedical Engineering Symposium　2015/11/16
In-Vitro Model and Cell Behaviors International-presentation

Proceedings of 2nd Biomedical Symposium and 1st Biomedical Engineering Symposium　2015/11/16
Towards the Patient-specific Design of Intracranial Stents for Advanced Flow Diversion Efficacy International-presentation

Proceedings of 2nd Biomedical Symposium and 1st Biomedical Engineering Symposium　2015/11/16
In-Vitro Model with Flow for Surface Treatment for Endothelialization International-presentation

Interdisciplinary Cerebrovascular Symposium (Intracranial Stent Meeting 2015)　2015/11/14
The Parent Artery Configuration can Induce Flow Pattern and its Stent Pattern International-presentation

Interdisciplinary Cerebrovascular Symposium (Intracranial Stent Meeting 2015)　2015/11/14
Analysis of Relationship Between Stent Structure and Flow Stagnation Using Self-Organizing Maps for Realistic Aneurysm International-presentation

Interdisciplinary Cerebrovascular Symposium (Intracranial Stent Meeting 2015)　2015/11/13
Development of Evaluation System for Cardiac Ablation Catheter on Electrode Cooling and Tissue Temperature International-presentation

International Workshop on Flow Dynamics and Spintronics　2015/11/12
血流から考える脳動脈瘤用最適化ステントの開発

第 9 回 CVC 千葉血管障害の原点を考える会　2015/11/05
Comparison Between CFD and MRI with 2D Velocity Vector Field and 3D Streamline in the Cerebral Aneurysm International-presentation

Interdisciplinary Cerebrovascular Symposium (Intracranial Stent Meeting 2015)　2015/11
Visualization of Flow Patterns through the Aneurysmal Orifice after Flow Diverter Optimizations with Different Objective Functions International-presentation

Interdisciplinary Cerebrovascular Symposium (Intracranial Stent Meeting 2015)　2015/11
医療機器の開発に向けた海綿骨内の数値流体力学解析

東北大学-信州大学共催シンポジウム　2015/10/23
Cell density distribution around the wire with flow condition International-presentation

The Fifteenth International Symposium on Advanced Fluid Information　2015/10
Development of a New Catheter with Innovative Concepts for Selective Venous Sampling - Preliminary CFD Study International-presentation

The Fifteenth International Symposium on Advanced Fluid Information　2015/10
Development of a Program for Blood flow and Cell Behaviors Based on LBM Method (third report) International-presentation

AFI-TFI　2015/10
Research of Friction and Drilling on Bio-composite Model (third report) International-presentation

AFI-TFI　2015/10
CFD Alanyses for the flow in Cancellous Bone with LBM International-presentation

The 8th Asian-Pacific Conference on Biomechanics　2015/09
Lesion Size Comparison of Catheter Ablation between Open Irrigation and Vibration under No Flow Condition International-presentation

Eighth Asian-Pacific Conference on Biomechanics　2015/09
Study of mechanical properties of acrylic composite for drilling bone biomodel International-presentation

International Tribology Conference　2015/09
脳動脈瘤治療用ステントにおける自己組織化マップを用いた最適形状解析

日本機械学会2015年度年次大会　2015/09
平均および最大流速の最適脳動脈瘤用ステントデザイン Optimized Intracranial Stent Designs with Average and Maximum Velocities

流体力学会年会2015　2015/09
Searching for valuable hemodynamic parameters for applying to optimization study International-presentation

9th European Solid Mechanics Conference　2015/07/07
Surface treatment on wire for increasing endothelialization International-presentation

9th European Solid Mechanics Conference　2015/07/06
医療機器の治験前評価法の開発

機械的補助循環が凝固・線溶因子に与える影響、基礎と臨床　2015/07/02
Comparison of the velocity vector field under different boundary conditions in a complex geometry with different experimental methods and numerical simulation International-presentation

China-Japan Joint Workshop on Flow Dynamics and Transport Phenomena　2015/06/24
Comparison of the velocity vector field in a cerebral aneurysm with different methods of PIV,CFD and MRI International-presentation

Beijing University of Technology　2015/06/23
Design analysis using optimization International-presentation

Beijing University of Technology　2015/06/23
CFDで何をみるのか，見えるのか AVEC CFD 2015 Analysis and Visualization Exhibition of Cerebral aneurysms using CFD

第38回日本バイオレオロジー学会年会　2015/06
Introduction of Optimization of Design using Combination of Lattice Boltzmann Method as CFD and Simulated Annealing for Reduction of Flow Speed International-presentation

1st NUAA-Tohoku University Joint Symposium on Fluid Science, Aerospace Engineering and Smart Structure Technology　2015/06
Manufacture-Oriented Design Optimization for a Flow Diverter Stent Using Lattice Boltzmann Method and Simulated Annealing International-presentation

11th World Congress of Structural and Multidisciplinary Optimization (WCSMO-11)　2015/06
Mechanical properties for drilling bone biomodel International-presentation

27ème Jornées Internationals Francophones de Tribologie (JIFT2015)　2015/05
Comparison of intra-aneurysmal velocity magnitude in a patient-specific model among PIV, CFD and MRI International-presentation

2015 ELyT lab Workshop　2015/02/20
Flow in cancellous bone International-presentation

2015 ELyT lab Workshop　2015/02/20
Optimization of endovascular prosthesis for the treatment ofcerebral aneurysms International-presentation

2015 ELyT lab Workshop　2015/02/20
The Effect of Vibration Ablation Catheter on the Temperature of the Electrode under 30 gf International-presentation

2015 ELyT lab Workshop　2015/02/20
Introduction of Three Strut Optimization Strategies towards the Design of Efficient Flow-Diverter Stents International-presentation

2015 ELyT lab Workshop　2015/02
Tohoku-Lyon collaboration, past and future International-presentation

France-Japan research collaboration seminar(5th SciVal user conference)　2015/01/21
PIV, CFD, およびMRIにおける動脈瘤内流れ分布の比較

日本機械学会第27回バイオエンジニアリング講演会　2015/01
Discussions of pressure distribution in artery with stenosis and aneurysm International-presentation

ElyT　2014/02
Introduction of Design Optimization for Intracranial Stent International-presentation

Japan-China Joint Workshop on Bio, Material and Flow Dynamics　2014/02
Model Study of Single Ventricular Heart Syndrome and its Treatment International-presentation

ElyT　2014/02
Study of blood flow in cerebral aneurysm with coil International-presentation

ElyT　2014/02
The Effect of Vibration Ablation Catheter on the Temperature of the Electrode under 0.1 m/s Flow International-presentation

ElyT　2014/02
太田研紹介

信州大学・東北大学共催シンポジウム～感性工学と医工学の未来に向けて～　2014/02
外科用インプラント並びにこれに関連する器具及び計装装置の検査等に用いる力学的安全性評価用模擬骨の国際標準化

ＩＳＯ／ＴＣ１５０（外科用インプラント）とバイオセラミックスの国際標準化の状況　2014/01/28
アブレーションカテーテルの電極温度評価用システムの開発

第26回バイオエンジニアリング講演会　2014/01
A Study on Multiscale Model in the presence of Systemic-to-Pulmonary Shunt utilizing Open-source CFD software Palabos International-presentation

5TH ASIA PACIFIC CONGRESS ON COMPUTATIONAL MECHANICS & 4TH INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL MECHANICS　2013/12
Hemodynamic Numerical Simulation in Artery Complicated with both Stenosis and Aneurysm in Different Shape and Position International-presentation

5TH ASIA PACIFIC CONGRESS ON COMPUTATIONAL MECHANICS & 4TH INTERNATIONAL SYMPOSIUM ON COMPUTATIONAL MECHANICS　2013/12
Observation of filling process in injection molding for fabrication of bone biomodel International-presentation

ICBME　2013/12
Analysis of Relationship between Lipid Environment and Protein Nanopore Properties- Toward Creation of Red Blood Cell Model with Various Membrane Strength- International-presentation

AFI/TFI　2013/11/27
Optimized Stent International-presentation

The 10th ICFD　2013/11/27
Membrane Channel Dynamics Depended on Lipid Environment International-presentation

The 10th ICFD　2013/11/26
Channel Properties of Membrane Proteins on Lipid Bilayers International-presentation

AFI/TFI　2013/11
Classification of blood flow in cerebral aneurysm considering the parent artery curves International-presentation

ASME 2013 International Mechanical Engineering Congress & Exposition　2013/11
Classification of flow pattern in neck based considering the parent artery curves and stent implantation International-presentation

ICS 2013　2013/11
Development of a Program for Blood flow and Cell Behaviors Based on LBM Method International-presentation

AFI/TFI　2013/11
Development of Visualization System for Injection Molding by using PVA International-presentation

The 10th ICFD　2013/11
Influence of Ni-Ti Wire under the Shear Stress Environment on Endothelialization International-presentation

The 10th ICFD, Sendai　2013/11
Introduction of IFS Liaison Office Activities International-presentation

10th ICFD　2013/11
Optimization of stent design to increase the porosity International-presentation

ICS 2013　2013/11
PIV ANALYSIS FOR FLOW PATTERN AROUND ABLATION CATHETER TO OBSERVE THE FLOW EFFECT ON ELECTRODE International-presentation

ASME 2013 International Mechanical Engineering Congress & Exposition　2013/11
Research of Friction and Drilling on Bio-composite Model International-presentation

AFI/TFI　2013/11
Stagnant Blood Flow in Intracranial Aneurysms: A Possible Association with Atherosclerosis International-presentation

The 10th ICFD　2013/11
The Effect of Vibration of Ablation Catheter on the Temperature of the Electrode International-presentation

The 10th ICFD　2013/11
Guidewire Simulator for Intravacular Surgery International-presentation

2013 UPM-Kyutech Symposium of Applied Engineering and Sciences　2013/10
Optimization of blood flow for intracranial stent International-presentation

International Workshop on Flow Dynamics related to Energy, Aerospace and Material Processing KTH　2013/09/10
Density change of smooth muscle cells in co-culture model under shear stress with spatial gradient related to the development of cerebral aneurysm International-presentation

The EMBO meeting 2013　2013/09
Electrophysiological properties of engineered FhuA ΔC/Δ4L protein nanopore affected by lipid bilayer environment International-presentation

The EMBO meeting 2013　2013/09
Friction of Medical Materials on PVA Hydrogel in Physiological Lubrication International-presentation

World Tribology Congress 2013　2013/09
せん断応力を負荷した共存培養モデル内の血管平滑筋細胞からのMMPの産生量の変化

日本機械学会2013年度年次大会　2013/09
Comparison of flow patterns around stenotic area in elastic PVA-H model and in rigid-like silicone model International-presentation

PIV 2013 Conference　2013/07
Correlation between Reynolds number and stenosis morphology in eccentric and concentric artery models International-presentation

PIV 2013 Conference　2013/07
Application of optimization for design of intracranial stent with blood flow reduction as objective function International-presentation

World Congress on Structural and Multidisciplinary Optimization　2013/05
Microbial Pore-Forming Protein Properties Depended on Lipid Environment International-presentation

NIH-Tohoku UNiversity JSPS Symposium　2013/05
Friction of Medical Materials in Contact with PVA Hydrogel in Physiological Conditions International-presentation

2013 annual ElyT workshop　2013/03
血流低減を目的とした脳動脈瘤用ステントデザインの最適設計

第62回理論応用力学講演会　2013/03
Study of the coil effect within an intracranial aneurysm International-presentation

2013 annual ElyT workshop　2013/03
Evaluation for Drilling Properties of Bone Models International-presentation

2013 annual ElyT workshop　2013/03
親血管形状による動脈瘤の分類に対するステントストラットパターンの最適化に関する研究

第25回バイオエンジニアリング講演会　2013/01
実形状動脈瘤を用いたステント形状最適化プログラム開発に関する研究

安西眸，Jean-Luc Falcone，Bastien Chopard，太田信　2013/01
せん断応力を負荷した共存培養モデル内の血管平滑筋細胞の形質変化

第25回バイオエンジニアリング講演会　2013/01
血管内ガイドワイヤシミュレータの研究

第25回バイオエンジニアリング講演会　2013/01
医療デバイス周りの血流流体力学的見地からの血栓形成

日本バイオマテリアル学会大会シンポジウム2012　2012/11/27
FLOW ANALYSIS OF STENOSIS AND ANEURYSM USING HYDROGEL FOR SOFT TISSUE SIMULATION International-presentation

Syracuse University –Tohoku University Seminar　2012/11/08
血管狭窄の硬さが血管拡張と狭窄下流部の血流に与える影響

2012年日本脳神経血管内治療学会　2012/11
骨組織を模擬したモデル材料におけるドリリング特性の評価

日本バイオマテリアル学会大会シンポジウム2012　2012/11
Flow analysis of stenosis and aneurysm using hydrogel for comparison to computational simulation International-presentation

MECHANICAL ENGINEERING and MATERIALS SCIENCE, Pittsburgh University　2012/10/11
Stent designs for efficient reduction of intra-aneurismal flow with various aneurysms International-presentation

The 9th International Iterdisciplinary cerebrovascular Symposium (ICS12)　2012/10
Modeling Flow Diverter Stent using Porous Media International-presentation

The 9th International Iterdisciplinary cerebrovascular Symposium (ICS12)　2012/10
Classification of Flow pattern in neck based on parent artery configuration and optimized stent implantation International-presentation

The 9th International Iterdisciplinary cerebrovascular Symposium (ICS12)　2012/10
PVA-H 血管バイオモデルの冷却時間と厚さ制御に関する研究

第23回バイオフロンティア講演会　2012/10
Hemodynamics Effect of Y-Configuration Stenting on Basilar Tip Aneurysm International-presentation

The 9th International Iterdisciplinary cerebrovascular Symposium (ICS12)　2012/10
Experimental Validation of FEA-Based Workflow to Simulate Flow Diverting Stent Deployment in Intracranial Aneurysms International-presentation

The 9th International Iterdisciplinary cerebrovascular Symposium (ICS12)　2012/10
Efficacy of Mechanical Vibration on Radiofrequency Catheter Ablation International-presentation

The 5th Asia-Pacific Heart Rhythm Society Scientific Session In Conjuction with 8th Asia-Pacific Atrial Fibrillation Symposium　2012/10
Localization of Disturbed Blood Flow in Intracranial Aneurysms : A Possible Association with Atherosclerosis International-presentation

The 9th International Iterdisciplinary cerebrovascular Symposium (ICS12)　2012/10
Effect of the Aspect Ratio of Cerebral Aneurysms on Blood Flow Reduction after Optimized Stent Placement International-presentation

Ninth International Conference on Flow Dynamics　2012/09/20
Electrophysiological Properties of Bacterial Membrane Channel Proteins Depending on Lipid Component and Bilayer Stability International-presentation

Ninth International Conference on Flow Dynamics　2012/09/20
Ultrasound Radiation Force Driven B-Flow Twinkling Sign for Microcalcification Detection International-presentation

The 12th International Symposium on Advanced Fluid Information and Transdisciplinary Fluid Integration (AFI/TFI-2012)　2012/09/20
Development of stent for cerebral aneurysm using fluid dynamics International-presentation

2012 Beijing International Symposium on Biomechanics　2012/09/04
Comparison between Agarose gel and PVA-H Biomodels for Evaluation of Ablation Catheter International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Flow Analysis in Cerebral Aneurysm Model with Transparent Coils Placement International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Relationship between Fluid Shear Stress and the Phenotype Change of Smooth Muscle Cells in a Co-culture Model International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Size Validation of an Adrenal Vein Model for Development of an In Vitro Model with Realistic Geometrical Structure International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Friction and thermal Properties in Drilling of Bone Biomodels International-presentation

Ninth International Conference on Flow Dynamics　2012/09
脳動脈瘤に対するステントストラット位置の自動最適化に関する研究

日本機械学会2012年度年次大会　2012/09
Channel Properties of Membrane Proteins on Lipid Bilayer International-presentation

AFI/TFI-2012　2012/09
Characterization of Design of Stent Strut Positioning using LBM Method International-presentation

AFI/TFI-2012　2012/09
Neumerical and Experimental Study of Flow in Stenosis models with Several Mechanical Properties International-presentation

Ninth International Conference on Flow Dynamics　2012/09
ステントストラットパターンの最適化を持ちたステント開発に関する研究

日本機械学会2012年度年次大会　2012/09
Measurement of Pressure Drop for Modeling Intracranial Flow Diverter Stent Using Porous Medium International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Tribology of Medical Materials on PVA-H Biomodel International-presentation

AFI/TFI-2012　2012/09
Optimum Design of Flow Diverter Stent Associated with Arterial Geometries International-presentation

Ninth International Conference on Flow Dynamics　2012/09
A Development of Lattice Boltzmann Model and Lumped Parameter Model Connection for Cardiovascular Multiscale Analysis International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Simulation of Hemodynamics in Artery with Aneurysm and Stenosis International-presentation

Ninth International Conference on Flow Dynamics　2012/09
Oscillatory and Stagnant Flow in Intracranial Aneurysms: A Possible Association with Atherosclerosis International-presentation

AFI/TFI-2012　2012/09
テーラーメイド医療ステントの開発から医療機器の国際標準規格まで

第4回流体科学におけるバイオ・医療に関する講演会　2012/07/26
Flow measurement using soft material for comparison of computational simulation International-presentation

German Research School for Simulation Sciences GmbH　2012/07/12
PIV Measurement of Inflow through Cerebral Aneurysmal Neck of PVA-H Biomodel with Compliant Wall International-presentation

8th European Solid Mechanics Conference　2012/07
The Design Characteristics Extracted From an Optimal Flow Diverter in an Ideal Side-wall Aneurysm Using Lattice Boltzmann Method International-presentation

8th European Solid Mechanics Conference　2012/07
軟組織内微細石灰化のB-Flow

日本超音波医学会　2012/05
Characterization and image analysis of heteroheptameric structure on staphylococcal gamma-hemolysin transmembarne pore International-presentation

Eighth International Conference on Flow Dynamics　2011/11/09
Effect of Aspect Ratio of Cerebral Aneurysm on flow reduction wuth stent International-presentation

Eighth International Conference on Flow Dynamics　2011/11/09
Methodology of Evaluation for Medical Devices Using In-vitro/In-silico Biomodel International-presentation

MHS,2011 International Symposium on Micro-NanoMechatronics and Human Science　2011/11/06
Control of wallthickness of blood vessel biomodel made of poly (vinyl alcohol) hydrogel by a three-dimentional rotating spin DIP-coating method International-presentation

ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION　2011/11
Crystal Structure of the Octameric Pore of Staphylococcal γ-hemolysin International-presentation

Eighth International Conference on Flow Dynamics　2011/11
Detection of Microcalcification in Soft Tissue Employing B-Flow International-presentation

Eighth International Conference on Flow Dynamics　2011/11
Development of a methodology for adaptation of refractive index under controlling kinematic viscosity for PIV International-presentation

ASME INTERNATIONAL MECHANICAL ENGINEERING CONGRESS AND EXPOSITION　2011/11
Effect of Initial Conditions of Stent Geometry on Optimized Design of Flow Diverters International-presentation

Eighth International Conference on Flow Dynamics　2011/11
Friction Analysis of Biometal on PVA Biomodel International-presentation

Eighth International Conference on Flow Dynamics　2011/11
Influence of Plaque Movement on Blood Flow and Blood Vessel around Stenosis Area International-presentation

Eighth International Conference on Flow Dynamics　2011/11
Involvement of ERK in Morphological Response of Endothelial Cells to Spatial Gradient of Shear Stress International-presentation

Eighth International Conference on Flow Dynamics　2011/11
Local Blood Flow Instability and Oscillatory Shear in Intracranial Aneurysms International-presentation

Eighth International Conference on Flow Dynamics　2011/11
Observation of Behavior of Injection for Composite Material using Micro-CT International-presentation

Eighth International Conference on Flow Dynamics　2011/11
PIV Mesurement of Steady Flow in PVA Model with Compliant Wall as Cerebral Aneurysm International-presentation

Eighth International Conference on Flow Dynamics　2011/11
微細石灰化を含んだ乳房組織を模擬したPVA phantomの実験的研究

第49回人工臓器学会　2011/11
Friction of Medical Metallic Alloys on Soft Tissue Biomodel International-presentation

International Tribology Conference　2011/10
PVAバイオモデルを用いたアブレーションカテーテルの温度分布の評価に関する研究

第22回バイオフロンティア講演会　2011/10
Assessment of stent using in vitro/-silico biomodelling International-presentation

8th International Interdisciplinary cerebrovascular Symposium and 11th Oriental Conference of Interventional Neuroradiology and 6th East Asian Conference of Neurointervention　2011/09/08
Analysis of cell adhesion on PVA-H for developing vessel bio-model with dynamical and biological responses International-presentation

24th European Conference on Biomaterials The Annual Conference of the European Society for Biomaterials　2011/09
Development ofthe design of flow diverters using automated optimization based on lattice boltzmann method International-presentation

8th International Interdisciplinary cerebrovascular Symposium and 11th Oriental Conference of Interventional Neuroradiology and 6th East Asian Conference of Neurointervention　2011/09
Friction Behavior of Medical Metallic Alloys against Biomimetic Poly (vinyl alchol) Hydrogel International-presentation

24th European Conference on Biomaterials The Annual Conference of the European Society for Biomaterials　2011/09
Influence of plaque stiffness on hemodynamics based on experimental studies with vitro PVA biomodel International-presentation

8th International Interdisciplinary cerebrovascular Symposium and 11th Oriental Conference of Interventional Neuroradiology and 6th East Asian Conference of Neurointervention　2011/09
Optimization of Stent Strut Pattern for Cerebral Aneurysm International-presentation

8th International Interdisciplinary cerebrovascular Symposium and 11th Oriental Conference of Interventional Neuroradiology and 6th East Asian Conference of Neurointervention　2011/09
Study on Effect of Blood Flow Reducing by Stent International-presentation

8th International Interdisciplinary cerebrovascular Symposium and 11th Oriental Conference of Interventional Neuroradiology and 6th East Asian Conference of Neurointervention　2011/09
PIV MEASURED HEMODYNAMIC STUDY WITH SEVERAL STENTS IN A CEREBRAL ANEURYSM MODEL FOR NEW STENT DESIGN International-presentation

AJK2011　2011/07
未破裂脳動脈瘤の破裂リスクに関する3次元可視化システムを用いたCFD解析の試み

第34回日本バイオレオロジー学会年会,　2011/06
脳動脈瘤用ステントデザインの設計方法

京都大学再生医科学研究所セミナー　2011/04/21
フローダイバーターの脳動脈瘤ステント設計

SMAシンポジウム2010　2010/11/26
多機能なカテーテル評価のためのPVA-Hモデルを用いた循環路システムの開発

日本人工臓器学会,　2010/11/19
壁厚制御されたPVA-H血管バイオモデルの開発

日本人工臓器学会　2010/11/19
Development of in vitro system for intracranial stent evaluation International-presentation

Swiss/Japan International Seminar on Medical Emgineering Based on Vessel Biology　2010/11/15
Development of vessel biomodel with dynamic and biological properties by cell attachment on PVA-H International-presentation

Swiss/Japan International Seminar on Medical Emgineering Based on Vessel Biology　2010/11/15
欧州研究枠組みを利用して -FP6@neuroIST project-

J-Bilat 第5回セミナー　2010/11/11
Analyzing Blood Flow in Bifurcated Artery with Cerebral Aneurysm Using Two Stents International-presentation

Seventh international Conference on Flow Dynamics　2010/11
Characterization of γ-Hemolysin on Liposome International-presentation

AFI/TFI 2010　2010/11
Development of Cell-Matrix Adhesion Techniques on Transparent PVA-H for Vessel Biomodeling International-presentation

Seventh international Conference on Flow Dynamics　2010/11
Development of PVA-H stenosis model International-presentation

Swiss/Japan International Seminar on Medical Emgineering Based on Vessel Biology　2010/11
Development of PVA-H Stenosis Model for PIV Measurement International-presentation

Seventh international Conference on Flow Dynamics　2010/11
Development of Stent for Cerebral Aneurysm based on Optimization International-presentation

AFI/TFI 2010　2010/11
Friction Properties of PVA-H for Biomodel and Steel Ball for Medical Devices International-presentation

AFI/TFI 2010　2010/11
Mechanical Properties and Microstructure of Injected Biomodeling International-presentation

Seventh international Conference on Flow Dynamics　2010/11
PIV measured hemodynamic study with several stents in a cerebral aneurysm model International-presentation

Swiss/Japan International Seminar on Medical Emgineering Based on Vessel Biology　2010/11
Tribological study on metallic alloy used for stent against blood vessel biomodel International-presentation

Swiss/Japan International Seminar on Medical Emgineering Based on Vessel Biology　2010/11
歯科インプラント手術トレーニング用骨バイオモデリングの力学的特性に関する研究

日本人工臓器学会　2010/11
透明Poly (vinyl alcohol) Hydrogel バイオモデル上への血管細胞の効果的付着技術の開発

日本バイオマテリアル学会2010　2010/11
Cell adhesion on PVA-H for development of biomodel with biological response International-presentation

International Mini Symposium for Biomechanics and Intracranial Stent　2010/10/20
4次元CTによる新しい血量速度計測用の開発と基礎的検討

日本放射線技術学会　2010/09/22
State-of-the-Art CT Imaging Techniques for Cerebrovascular Disease

画像処理研究会　2010/09/22
Cell Adherence on Transparent PVA-H Coated with Extracellular Matrix International-presentation

23th European Conference on Biomaterials,　2010/09/12
血管バイオモデル内流れのPIV計測のための疑似血液流体開発

日本流体力学学会年会 2010　2010/09/10
Computational Design of Intracranial Stent Using 3D Visualization System International-presentation

Live International Neuroradiology Conference (Inconjunction with the 7th ICS)　2010/09
Flequency-Dependence of Blood Vessel Biomodel Made of Poly(vinyl alcohol) Hydrogel International-presentation

23th European Conference on Biomaterials　2010/09
Subunit arrangement analysis of staphylococcal γ-hemolysin heteroheptameric transmembrance pore

生物物理 supplement2　2010/09
Towards the Simulations of Endovascular Treatment for Cerebral Aneurysm International-presentation

The 6th Beijing International Symposium on biomechanics　2010/08/26
Development of Blood-Mimicking Fluid with Ajusted Refractive Index and Kinematic Viscosity for Applying to Particle Image Velometry International-presentation

6th World Congress of Biomechanics　2010/08/03
Simulations of Endovascular Treatment for Cerebral Aneurysm International-presentation

6th World Congress of Biomechanics　2010/08/02
Analysis of Mechanical Properties and Microstructure for Development of Bone-Biomodeling International-presentation

6th World Congress of Biomechanics　2010/08
Development of Fundamental Techniques of Cell Adhesion on Transparent PVA-H for Biomodeling International-presentation

6th World Congress of Biomechanics　2010/08
Modification of transparent poly(vinyl alcohol) hydrogel with extracellular matrix promotes effective cell adhesion for biomodeling International-presentation

International Conference on Cellular & Molecular Bioengineering　2010/08
Molecular Architecture Analysis of Staphylococcal hemolysin Heteroheptameric Transmembrance Pore : Construction of Three-Dimenational Structure with Subunit Arrangement Mismatch Based on High-resolution Electron Microscopic Image International-presentation

6th World Congress of Biomechanics,　2010/08
Analysis of Three-dimetional Structure and Subunit Mismatch in Staphylococcal γ-Hemolysin Heterohepameric Transmembrance Pore International-presentation

Microscopy and Microanalysis　2010/08/01
脳動脈用ステントにおける流体力学的理論解析の試み

第16回日本血管内治療学会総会　2010/07/23
脳動脈用ブレブ部分の流れの数値解析とその血管撮影による検証

第16回日本血管内治療学会総会　2010/07/23
Biomodel for Development of Intracranial Stent International-presentation

SIRIC International Symposium 2010　2010/07/02
Computational Simulation of Intracranial Stent using 3D visualization system International-presentation

SIRIC International Symposium 2010　2010/07/02
血管バイオモデルを用いたＰＩＶによる瘤内コイル周りの血流解析

第1回国際バイオレオロジーシンポジウム,第33回日本バイオレオロジー学会年会　2010/06/03
ブドウ球菌の2成分性毒素γヘモリジン膜孔複合体における分子配置解析と立体構造予測

日本顕微鏡学会第66回学術講演会　2010/05/24
Development of Bone-Biomodeling for Surgical Simulations International-presentation

2010 Annual ELyt Workshop　2010/03
Development of Stent Designing for Cerebral Aneurysm International-presentation

2010 Annual ELyt Workshop　2010/03
In-virto blood flow circulation system using PVA model for evaluating medical devices International-presentation

2010 Annual ELyt Workshop　2010/03
Present Study of Poly(vinyl alcohol) Hydrogel Based Biomodel for Endovascular Treatment International-presentation

2010 Annual ELyt Workshop　2010/03
PVAバイオモデルの壁厚測定

日本機械学会東北支部第45期総会・講演会　2010/03
Tribology of PVA biomodel (Biocath project) International-presentation

2010 Annual ELyt Workshop　2010/03
ブドウ球菌の2成分性毒素γヘモリジンが形成するヘテロヘプタマ−膜孔複合体の立体構築とサブユニット間配置の定量的解析

日本農芸化学会2010年度（平成22年度）大会　2010/03
Rheology-Fluid Dynamics of Blood Flow Modelling and Simulation-Basics of Fluid International-presentation

The Australasian College of Phlebology, 13th Annual Scientifc Meeting & Workshops　2010/02/06
FROTTEMENT LUBRIFIE DU CONTACT PVA / ACIER International-presentation

le comitee; scientifique de JIFT 2010　2010/02
Jet-Fluid Effects on the Stented-Flow Structure in the Cavity of Cerebral Aneurysm International-presentation

Biophysical Society, 54th annual meeting　2010/02
Development of stent for Cerebral Aneurysm International-presentation

the Ninth International Symposium on Advanced Fluid Information and Transdisciplinary fluind Integration(ATI/TFI 2009),　2009/11
Experimental Study on a Catheter Movement for Evaluating Catheter Designs Using an In-Vitro Tracking System International-presentation

Sixth International Conference on Flow Dynamics(ICFD),　2009/11
コイルを留置させた脳動脈瘤モデルでの血流の定量的測定法の開発

第25回日本脳神経血管内治療学総会　2009/11
ポリビニルアルコールハイドロゲルを用いた3次元血管モデルの構築と力学的特性の計測

第３１回日本バイオマテリアル学会大会　2009/11
脳動脈瘤コイル塞栓後の血流変化の計算機流体力学による評価

第25回日本脳神経血管内治療学総会　2009/11
Analysis of Drilling Bone Biomodeling International-presentation

International Bone-Tissue-Engineering Congress　2009/10
Three-dimensional structure analysis of staphylococcal γ-hemolysin heteroheptameric transmembrance pore complex

日本生物物理学会第47回年会講演　2009/10
3次元可視化システムを用いた血流数値解析の可視化

日本機械学会2009年度年次大会　2009/09/14
3D Observation of Expansion of Stent and Elastic Recoil using Micro-CT International-presentation

World Congress on Medical Physics and Biomedical Engineering　2009/09
Catheter and guidewire simulator for intravascular surgery (Comparison between simulation results and medical images) International-presentation

The World Congress on Medical Physics and Biomedical Engineering 2009　2009/09
Development of Particle Image Velocimetry System for intra-aneurysmal flow in arterial biomodel made of Poly (vinyl alcohol) hydrogel International-presentation

Third Switzerland-Japan workshop on Biomechanics 2009(SLB 2009),　2009/09
Friction properties of PVA-H / steel ball contract International-presentation

World Tribology Congress 2009　2009/09
Molecular architecture analysis of Staphylococcal γ-hemolysin heteroheptameric transmembrane pore complex International-presentation

Third Switzerland-Japan workshop on Biomechanics 2009(SLB 2009),　2009/09
Poly (vinyl alcohol)動脈瘤バイオモデル内流れのParticle Image velocimetry 計測における作動流体開発

計測自動制御学会東北支部４５周年記念学術講演会　2009/09
Poly(vinyl alcohol) Hydrogel with Controlled Wall Thickness for Blood Vessel Biomodelilng International-presentation

Third Switzerland-Japan workshop on Biomechanics 2009(SLB 2009),　2009/09
コイルが留置された脳動脈瘤モデル内の流れに関する研究

日本機械学会２００９年度年次大会　2009/09
ブドウ球菌の2成分性毒素γヘモリジンが形成するヘテロヘプタマー膜孔複合体の立体構造解析

第54回日本ブドウ球菌研究会　2009/09
生体材料を活用した管内MR流体流動の動的応答と高機能化

日本混相流学会年会講演会2009　2009/08/07
Evaluation of Poly (vinyl alcohol) Hydrogel Biomodeling by Using Ultrasound International-presentation

International Intracranial Stent Meeting 2009　2009/08/04
3D Visualization of numerical simulation of blood flow on intracranial stent International-presentation

International Intracranial Stent Meeting 2009　2009/08
A parametric model for side wall and bifurcation cerebral aneurysms International-presentation

International Intracranial Stent Meeting 2009　2009/08
Computational Fluid Dynamics of Carotid Arteries after Carotid Endarterectomy or Carotid Artery Stenting based on Postoperative Patient-specific Data International-presentation

International Intracranial Stent Meeting 2009　2009/08
Development of Bone Biomodeling for drilling International-presentation

International Intracranial Stent Meeting 2009　2009/08
Experimental Study on a Catheter Movement for evaluating Catheter Designs International-presentation

International Intracranial Stent Meeting 2009　2009/08
Improvement of Dynamic Four-dimensional CT Angiography (DFA) and apply to the Computational Fluid Dynamics International-presentation

International Intracranial Stent Meeting 2009　2009/08
Measurement of Flow Speed of In Vitro Aneurysm Models with Coils Using Particle Image Velocimetry (PIV) International-presentation

International Intracranial Stent Meeting 2009　2009/08
Numerical Analysis on Characteristic Effects of Stent in Cerebral Vessels International-presentation

International Intracranial Stent Meeting 2009　2009/08
Optical properties measurement of Poly (vinyl alcohol) hydrogel biomodel for applying Particle Image Velocimetry International-presentation

International Intracranial Stent Meeting 2009　2009/08
黄色ブドウ球菌の2成分血球崩壊毒素γヘモリジンが形成する膜孔複合体の立体構造解析

日本顕微鏡学会第65回学術講演会　2009/05
Study on the Development of Blood Vessel Biomodeling with Realistic Mechanical Properties by Using Poly (vinyl alcohol) Hydrogel International-presentation

4th Asian Pacific Conference on Biomechanics　2009/04/17
Measurement of Dynamic Viscoelasticities and Sensory Evaluations of Poly (Vinyl Alcohol) Hydrogel for Development of Oral Mucosa Model International-presentation

4th Asian pacific Conference on Biomechanics　2009/04/15
Study on a Catheter Movement with Poly (vinyl alcohol) Hydrogel for the Development of an In-Vitro Tracking System International-presentation

Fourth Asian Pacific Conference on Biomechanics　2009/04/15
血管内カテーテル/ガイドワイヤシミュレータ（計算結果と医用画像との比較）

第48回日本生体医工学会大会　2009/04
Blood flow in cerebral aneurysm; Computational simulations and biomodels International-presentation

ヨンセイ大学　2009/03/30
Blood flow in cerebral aneurysm; Computational simulations and biomodels International-presentation

Special lecture in Yonsei University　2009/03/30
Computational Studies on Characteristic fluid behavior in the stented Cerebral Aneurysm International-presentation

American Physical Society March meeting　2009/03/18
医療デバイス開発のための要素技術開発-バイオモデルとシミュレーション-

低侵襲医療機器実現化フォーラム「脳外科領域の血管内治療」　2009/03/12
Tribological behavior of PVA hydrogel for biological model of arteries International-presentation

International Conference on Bioengineering & Biomaterials　2009/03
The Effect of Computational Simulation on EndovascularTreatments of Cerebral Aneurysm International-presentation

the Third International Symposium on Biomechanics,Human Function and Information Science　2009/02/21
Study of Searching Method for Position of Stent Strut to Decrease Blood flow in Cerebral Aneurysm International-presentation

the Third International Symposium on Biomechanics,Human Function and Information Science　2009/02/20
Evaluation of After CAS Operation by Flow and Wall Shear Stress Using CFD Simulation International-presentation

the Third International Symposium on Biomechanics,Human Function and Information Science　2009/02
The Effect of Computational Simulation on EndovascularTreatments of Cerebral Aneurysm International-presentation

the Third International Symposium on Biomechanics,Human Function and Information Science　2009/02
Poly(Vinyl Alcohol)Hydrogelを用いた口腔粘膜モデルの開発

第21回バイオエンジニアリング講演会　2009/01
ステントストラット配置が脳動脈瘤モデル内の流れに与える影響

第21回バイオエンジニアリング講演会　2009/01
血管バイオモデリング開発を目的としたポリビニルアルコールハイドロゲルの力学的特性評価

第21回バイオエンジニアリング講演会　2009/01
脳動脈瘤内の血流減少における最適な箇所の探索

第21回バイオエンジニアリング講演会　2009/01
Development for Catheter Motion Tracking System Using Poly(vinyl alcohol) Hydro-gel Biomodel International-presentation

The Eighth International Symposium on Advanced Fluid Information and Transdiciplinary Fluid Integration　2008/12
Development of PVA-H as a biomodel International-presentation

ELyT Lab Workshop　2008/12
Evaluation of Compliance of Poly(Vinyl Alcohol) Hydrogel for Development of Arterial Biomodeling International-presentation

13th International Conference on Biomedical Engineering　2008/12
64列MDCTのCine Dynamis Scan による拍動嚢状動脈瘤モデルの壁運動描出

第24回日本脳神経血管内治療学会総会　2008/11
Introduction of JSPS Core to Core Program: Establishment of International Research Consortium for Advanced Biommedical Engineering in Interface Flow Dynamics for Blood Flows, Blood Vessels, and Biomaterials International-presentation

Fifth International Conference on Flow Dynamics　2008/11
The Effect of Neck Shape on Flow Pattern in Cerebral Aneurysm using Computational Fluid Simulation with Idealized Models International-presentation

Fifth International Conference on Flow Dynamics　2008/11
脳血管内カテーテル・ガイドワイヤシュミレータ

第24回日本脳神経血管内治療学会総会　2008/11
PVAハイドロゲルとメッシュ材料を用いた異方性血管モデルの制作

第19回バイオフロンティア講演会　2008/09
脈診用脈波計測装置、物性と形状を兼ね備えたバイオモデル

東北大学イノベーションフェア　2008/09
各ステントストラットが瘤内の血行動態へ及ぼす影響

機械学会 2008年度年次大会　2008/08
脳動脈ステントの動向

第6回「医療・福祉・環境における形状記憶合金の高機能化および応用に関する分科会　2008/08
脳動脈瘤用ステントによる血流制御と治療アセスメント

第33回CG・可視化研究会　2008/08
Heat Diffusion Characteristics of Magnetite Nanoparticles Dispersed Hydro-gel in AC Magnetic Field International-presentation

Intrenational Symposium on Nanotoxicology Assessment and Biomedical,Environmental Application of Fine Particles and Nanotubes　2008/06
Heat Diffusion Characteristics of Magnetite Nanoparticles Dispersed Hydro-gel in AC Magnetic Field International-presentation

The 7th International Conference on the Scientific and Clinical Applications of Magnetic Carriers　2008/05
Observation of Motion of Blood Vessel Biomodeling Made of Poly (Vinyl Alcohol) Gel with Ultrasound International-presentation

The 5th International Intracranial Stent Symposium　2008/05
Obsevation of Three-Dimentional Elastic Recoil of Balloon-Expandable Stent International-presentation

The 5th International Intracranial Stent Symposium　2008/05
Sensory Evaluation of Poly (Vinyl Alcohol) Gel for Surgical Operation of Soft Tissue International-presentation

The 5th International Intracranial Stent Symposium　2008/05
Several Stent Struts Increase Blood Flow Speed in Cerebral Aneurysm International-presentation

The 5th International Intracranial Stent Symposium　2008/05
The Effect of Neck Shape of Aneurysm on Inflow Zone at the Neck Using Computational Fluid Simulation International-presentation

The 5th International Intracranial Stent Symposium　2008/05
64列MDCTのCine Dynamic Scanによる拍動嚢状動脈瘤モデルの壁運動描出

日本放射線技術学会第64回総会学術大会　2008/04
The Effect of Boundary Condition with Ultrasound Measurement on Blood Flow Simulation in Carotid Artery International-presentation

the 2nd Interantional Symposium on Biomechanics, Healthcare and Information Science　2008/03/15
Poly (vinyl alcohol) gelを用いた口腔粘膜モデルの開発と一対比較法による物性評価

日本機械学会東北支部第43期総会・講演会　2008/03
Three Dimensional Behavior of Balloon-Expandable Stent using Micro-CT International-presentation

the 2nd Interantional Symposium on Biomechanics, Healthcare and Information Science　2008/03
脳動脈瘤ネックにおけるステントストラットパターンと瘤内の血行動態に関する研究

第20回バイオエンジニアリング講演会　2008/01
バイオモデリングと脳動脈瘤用ステント

日本生体医工学会専門別研究会第120回研究会　2007/11/12
Effest of Stenting Rotational Positions on Hemodynamics in a Cerebral Aneurysm International-presentation

AMERICAN SOCIETY OF NEURORADIOLOGY　2007/06

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Nakayama,T. Ohta,M. Rufenachat,D.A. Takahashi,A.
Cinematic Angiography for Assesments of blood Flow in Cerebral Aneurysm with Stents International-presentation

AMERICAN SOCIETY OF NEURORADIOLOGY　2007/06

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Ohta,M. Fujimura,N. Augsburger,L. Barath,K. Yilmaz,H Abdo,G. Ruefenachat,D.A.
The Effect to Hemodynamics of an Intracranial Aneurysm by a Difference of Stent Struct Design International-presentation

The 4th International Intracranial Stent Meeting　2007/04

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Toshio Nakayama, Makoto Ohta, Daniel A.Rufenachat Akira Takahashi
Optimisation of Stents for Aneurysm International-presentation

The 4th International Intracranial Stent Meeting　2007/04

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K. Srinivas, M Ohta, T. Nakayama, S. Obayashi T. Yamaguchi
Studies on Funstional Biomodeling of Cerebral Artery with Mechanical Properties using Poly (vinyl alcohole) Hydro-gel International-presentation

The 4th International Intracranial Stent Meeting　2007/04

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Hiroyuki KOSUKEGAWA, Keisuke MAMADA, Lei LIU, Kanju KUROKI, Toshiyuki HAYASE, Makoto OHTA
Quantification of Flow in aneurysm for Development of Intracranial Stent International-presentation

The 4th International Intracranial Stent Meeting　2007/04
From Micro-CT to Numerical Simulation:The Effect of Intracranial Stent on Hemodynamics in Cerebral Aneurysm International-presentation

The Third B-J-K symposium on Biomechanics　2007/03

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Toshio Nakayama, Makoto Ohta, Daniel A. Rufenachat, Akira Takahashi
In-vitro model of artery based on Poly vinyl alcohol (PVA) hydrogel (PVA-H) with low friction International-presentation

The 4th LYON-TOHOKU ENGINEERING & SCIENCE FORUM　2007/02
Bio-tribology of a catheter/biomodel vessel contact International-presentation

The 4th LYON-TOHOKU ENGINEERING & SCIENCE FORUM　2007/02
The Effect of Stenting with Difference Positions on Hemodynamics in a Cerebral Aneurysm International-presentation

The 9th International Symposium on Future Medical Engineering Based on Bio-nanotechnology　2007/01

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Toshio Nakayama, Makoto Ohta, Daniel A.Rufenachat Akira Takahashi
Development of fundamental technologies with use of in-vitro and in-silico models for endovascular treatments International-presentation

kick-off meeting of @neurIST　2006/02/08
Development of fundamental technologies with use of in-vitro and in-silico models for endovascular treatments International-presentation

Daniel A, RÜFENACHT, Pedro LYLYK, Toshiyuki HAYASE, Akira TAKAHASHI

Fifth International Symposium on Advanced Fluid Information (AFI-2005) —IFS-JAXA Joint Symposium—　2005/12/08
Subtracted Vortex Centres Path line method with Cinematic Angiography for evaluating flow in stented cerebral aneurysm International-presentation

Naoko Fujimura, Krisztina Barath, Stephan G. Wetzel, Luca Augsburger, Edouard Fonck, Hasan Yilmaz, German Abdo, Karl-Olof Lovblad, Nikos Stergiopulos, Daniel A. Rüfenach

The 2nd Japan-Switzerland workshop on biomechanics　2005/09/12
血管モデルと血流ダイナミクス

IVR学会夏期学術セミナー　2005/07/30
医療における工学の関わり～脳動脈瘤の血管内治療を例に～

宮城県脳ドック研究会　2005/07/26
Computer simulation, In-Vitro simulation and Patient data International-presentation

Intra Cranial Stent Meeting 2005　2005/03/16
16)Rheological changes after stenting of a cerebral aneurysm: a finite element modeling approach International-presentation

M. Ohta, S. Wetzel, P. Dantan, H. Yilmaz, K. O. Loevblad, P. Flaud, D. A. Rüfenacht

Cardiovascular and Interventional Radiological Society of Europe　2004/09
Experience in In-vitro Modeling of Intracranial Aneurysms International-presentation

OHTA M, HANDA A, AUGSBURGER L, WETZEL S, ABDO G, IWATA H, TSUTSUMI S, FASEL J, RÜFENACHT DA

International Workshop on Flow and Motion　2004/07
14)How to validate computer flow simulation results? – On the use of patient data based vascular model production and in-vitro model flow analysis. International-presentation

OHTA Makoto, AUGSBURGER Luca, FUJIMURA Naoko, WETZEL Stephan, IWATA Hiroo, TSUTSUMI Sadami, RÜFENACHT Daniel A

4th international symposium on future medical engineering　2004/06
13)Hemodynamic Studies of Coiling in Cerebral Aneurysm by Using Particle Image Velocemetry (PIV) Method International-presentation

Makoto OHTA, Vincent GARITEY, Olivier LEVRIER, Régis RIEU, Francis CASSOT, Daniel A, RUEFENACHT

42nd American Society of Neuroradiology Annual meeting　2004/05
超音波血管撮像用PVA-Hモデルの開発

M. S. S. Hashuro, Simon Tupin, 井上浩介, 早瀬敏幸, 太田信

超音波血管撮像用PVA-Hモデルの開発

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Industrial Property Rights 6

マウスガード及びマウスガード用乾燥ゲルの製造方法

堤定美, 太田信, 玄丞烋, 岡野仁夫

Property Type: Patent
マウスガードとその製造方法

堤定美, 太田信, 玄丞烋, 岡野仁夫

Property Type: Patent
PCT出願標準血管生成装置、血管評価装置、標準血管生成プログラム、血管評価プログラム、標準血管生成方法及び血管評価方法

Property Type: Patent
多機能体内留置ステント

山家智之, 太田信, 松木英敏, 佐藤文博, 堀義生, 白石泰之, 前田剛, 関根一光, 三浦英和, 角張泰之, 荒井真輔

Property Type: Patent
骨模型

太田信, 柴田幸彦, 及川直人, 片倉裕司

Property Type: Patent
生体模型のための粘膜材

太田信, 柴田幸彦, 及川直人, 片倉裕司

Property Type: Patent

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Research Projects 26

合併症を再現できる内視鏡手技シミュレータを展開し、有効な学習プログラムを構築する

菅野武, 太田信, 荒田悠太郎

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(C)

Institution: 東北大学

2022/04/01 - 2025/03/31
Effect of wall elasticity on hemodynamics inside patient-specific cerebral aneurysm

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2022/04/01 - 2025/03/31
慢性関節炎の微小血管塞栓術に関する基礎実験

小黒草太, 高瀬圭, 石幡浩志, 権田幸祐, 太田信, 中村保宏, 大田英揮, 佐藤友美, 鎌田裕基

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 東北大学

2022/04/01 - 2025/03/31
Establishment of a prediction model for aneurysm development by mathematical vascular branching pattern classification and vascular travel standardisation.

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2022/04/01 - 2025/03/31
TiO2 layer formation on super elastic NiTi alloy via anodization

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Kitami Institute of Technology

2021/04/01 - 2024/03/31
Visualization of stroke risk using standard model of MRA vascular course and wall stress

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2021/04/01 - 2024/03/31
アイトラッキングによるカテーテル術者の目線解析と訓練に役立つ目線パターンの解明

庄島正明, 小泉聡, 太田信, 岡本吉弘

Offer Organization: 日本学術振興会

System: 科学研究費助成事業基盤研究(C)

Category: 基盤研究(C)

Institution: 埼玉医科大学

2021/04/01 - 2024/03/31

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実臨床データの収集と解析：脳血管内治療を実施する術者の経験と相関する目線パラメータを明らかにするために、実臨床データの収集を行った。3年間で30症例のデータ取得と解析を予定しているが、2021年度は、9件の血管内治療中の目線データの取得をおこなった。埼玉医科大学で7件、帝京大学で2件のデータ取得を行った。血管内治療手技の内訳は、脳動脈瘤コイル塞栓術が2件、フローダイバーター留置術が3件、脳動静脈奇形塞栓術が2件、脳腫瘍栄養血管塞栓術が1件、慢性硬膜下血腫に対する血管塞栓術が1件だった。非臨床実験：経験レベルの低い術者の目線データを収集・解析するために、血管モデルを作成し、模擬手術を実施中の術者の目線データを3年間で30被検者より収集することを予定している。2021年度は血管モデルの作成に取りかかった。当初は、半年かけて完成させる予定だったが、研究場所の変更と時期が重なってしまい、実施が遅れた。2021年度は血管モデルのCADモデルを作成し、それをプリントしてくれる業者（Bluepractice社）と打ち合わせをおこなった。いまだ血管モデルの細部の微調整を継続している。
Development of the implant for the reduction of vascular stenosis of AV fistula of hemodialysis patients

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2021/04/01 - 2024/03/31
Study of Structural and Thermal Properties of PVA as 3D Printing Material for Body Parts Modeling

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2020/04/01 - 2023/03/31
Characteristics of elasticity on suppression for progress and rupture in cerebral aneurysm

yamaguchi ryuhei

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2019/04/01 - 2022/03/31

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Mechanisms underlying growth and rupture of aneurysms are poorly understood. Although wall shear stress (WSS) in elastic aneurysms is examined using fluid structure interaction, it has not been sufficiently validated using experimental modalities, such as particle image velocimetry (PIV) or phase contrast magnetic resonance imaging. We investigated pulsatile flow in elastic patient-specific cerebral aneurysm using PIV. Phantom model was carefully fabricated using a specialized technique by silicone. We explored WSS and kinetic energy cascade (KEC) in elastic compared with a rigid models, at apex of bifurcation of middle cerebral artery in vitro. Effects of elasticity on WSS, WSS gradient, and tensile strength of aneurysm wall were also investigated, in addition to effect of wall elasticity on KEC compared to a rigid wall. Although WSSG around stagnation point had a large positive value, wall elasticity suppressed WSS magnitude around stagnation point and attenuated KEC.
Development of efficient nonclinical evaluation system for innovative medical equipment flow diverte

OKAMOTO YOSHIHIRO

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: National Institute of Health Sciences

2017/04/01 - 2022/03/31

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The shape of the flow diverters when implanted was evaluated, and it was found that the change in vessel shape before and after implantation was minimal.The objective was to predict post-implantation shape, but due to the difficulty of obtaining the device, the objective was changed to evaluating the pressure load on the vessel when the intravascular device is used. The basic characteristics of semi-compliant and compliant balloons during balloon catheter dilation were evaluated. We constructed an evaluation system to measure the relationship between the internal pressure of the balloon and the pressure applied to the blood vessel, and succeeded in clarifying the relationship between the internal pressure of the balloon and the pressure applied to the blood vessel, which had not been understood until now.
Development of a novel arterial lesion vessel model for pulsatile cerebrovascular circulatory simulation Competitive

Yusuke Tsuboko, Yoshihiro Okamoto, Makoto Ohta

Offer Organization: Institute of Fluid Science, Tohoku University

System: Collaborative Research Project of the Institute of Fluid Science, Tohoku University

Institution: Waseda University

2021/04 - 2022/03
Fluid mechanical basic research for the treatment of dissecting aortic aneurysms with multi-layered blood flow control stents

YUSUKE SUZUKI

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2018/04/01 - 2021/03/31

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A dissected blood vessel model was created. We designed a pulsatile flow circulation circuit incorporating a pseudo-dissected blood vessel model. Hemodynamic analysis was performed before and after placing the MFM stent in the true lumen. As a result, a pulsating water flow was observed in the false lumen before the MFM stent was placed, and an accelerated water flow was observed in the entry part. On the other hand, after the MFM stent was placed, the laminar flow was almost laminar, and no accelerated water flow was observed. From the above, it was considered that the water flow into the false lumen remains, but the water flow flowing into the false lumen through this MFM stent is rectified, the turbulence is reduced, and the shear stress applied to the false lumen wall is reduced. These results indicate that the MFM stent may be useful as a treatment for dissecting aortic aortic aneurysm.
Wearable Vital Sign System for Health Care Clothing based on FBG sensor

Ishizawa Hiroaki

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)

Category: Grant-in-Aid for Scientific Research (A)

Institution: Shinshu University

2016/04/01 - 2021/03/31

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By applying the Fiber Bragg Grating (FBG) sensor and thermocouple sensor, we have opened up the possibility of smart textiles that can continuously measure the vital signs such as blood glucose level, blood pressure vales, respiratory rate, and body temperature. From the characteristics of the pulse wave patterns measured at the pulsation point, it was clarified that continuous measurement of blood glucose level and blood pressure is possible. For application to washable textiles, plastic fiber optic FBGs can be used, and quartz-based FBG structural yarns and this weaving technology make it possible to introduce these sensors to elbow supporters and underwear. It revealed that the prototype-developed textiles can measure and evaluate the wearing condition and the physiological condition of the users. Furthermore, we have approached the detection principle of these sensors. Therefore, this research project has opened up the possibility of establishing a healthcare-clothing environment.
Development of new stent for the treatment of intracranial fusiform aneurysms to cure the aneurysmal wall and preserve perforators

Endo Hidenori

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2017/04/01 - 2020/03/31

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Using the data obtained from the human cases, we performed computational fluid dynamics (CFD) analysis. We calculated wall shear stress, oscillating shear index, relative residence time of the aneurysm to standardize these parameters. Then, We calculated the appropriate condition to cure the pathology of the aneurysmal wall and to preserve the perforators based on the theory of fluid engineering. We developed the design of the stent which can meet above mentioned condition based on the CFD data. We tried to create prototype stent to deploy into the aneurysm animal model to validate the proper design of the stent.
Pulmonary blood flow analysis based on morphological and functional images in chronic thromboembolic pulmonary hypertension

Ota Hideki

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2016/04/01 - 2019/03/31

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This study analyzed pulmonary blood flow with the use of 4-dimensional flow MRI and dual-energy CT in patients with chronic thromboembolic pulmonary hypertension. 1) Iodine-contrast-enhanced dual energy CT demonstrated significant changes of CT density in the lung parenchyma reflecting changes of distribution in pulmonary blood flow before and after balloon pulmonary angioplasty; the degree of changes were significantly correlated with mean pulmonary arterial pressure. 2) 4-dimensional flow demonstrated significant elevation of the wall shear stress after balloon pulmonary angioplasty; the degree of which was also correlated with the change of mean pulmonary arterial pressure.
Analysis of the mechanism of aortic diameter enlargement of Stanford type B dissection and development of prediction method

Yoshioka Ichiro

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2016/04/01 - 2019/03/31

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Before starting the FSI analysis, we reevaluated the results of treatment for type B aortic dissection. It is reconfirmed that it is difficult to predict the aortic expansion only by the morphological assessment. We attempted to analyze wall shear stress using finite element analysis (FSI analysis) from the topography of the aorta obtained from CT data and flow velocity conditions obtained from MRI examination. However, with regard to the movement of intimal flaps in aortic dissection, 4D MRI shows that movement is much greater in acute than in chronic, and it is difficult to incorporate this in fluid analysis. It turns out that it is difficult to make a prediction of aortic expansion in the early term of aortic dissection.
Research on endotheliaisation of optimal stent struts under blood flow(Fostering Joint International Research)

Ohta Makoto, Sen Itsu, Hirsh Sven, Fridrici Vincent

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Fund for the Promotion of Joint International Research (Fostering Joint International Research)

Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)

Institution: Tohoku University

2016 - 2018

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Based on the international collaborations with three places, we developed a smart deployment program of stent, a high efficient method for finding an aneurysm and a new material for biomodel. Also, we found a replying of cells from the wall shear stress. Especially, we successfully developed a new chamber with a strut and the results have a consistency to the previous results saying wall shear stress replying. This means that we find a optimal strut. This results is opened in international conference on 2019 and journal paper. These findings show the possibility of a pipeline from diagnosis of aneurysm to design of optimal stent.
stent optimization for endothelialization with flow condition

OHTA MAKOTO, Iwata Hiroo, Kobayashi Hisatoshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2013/04/01 - 2016/03/31

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The most effective results in this project is development of program for optimization of stent design and the success of endothelialization using improvement of surface of stent. Next generation of stent is necessary for avoiding restenosis and recanalization. To solve these problems, this project was performed for optimization of stent designs and surface treatment. The results show that the development of program leads the optimization of stent for thrombosis.
Prediction of the wall property and rupture risk of cerebral aneurysms based on the computational fluid dynamics

Niizuma Kuniyasu, SUGIYAMA SHIN-ICHIRO, NAKAGAWA ATSUHIRO, HAYASE TOSHIYUKI, OHTA MAKOTO, FUNAMOTO KENICHI, ARAFUNE TATSUHIKO, WASHIO TOSHIKATSU

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (A)

Category: Grant-in-Aid for Young Scientists (A)

Institution: Tohoku University

2013/04/01 - 2016/03/31

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The purpose of this study was to build a large-scale cerebral aneurysm database including computational fluid dynamics (CFD) analysis, and to predict wall property and rupture risk. In the 3 years around 500 cases were included. Based on the database, we reported that the yellowish wall can be predicted by CFD. In addition, we revealed that rupture risk or recanalization after coil embolization could be predicted by CFD. Further analysis based on the database and outpatient clinic system are planned.
Development of a new catheter for segmental adrenal venous sampling

Seiji Kazumasa, Takase Kei, Morimoto Rei, Oota Makoto, Haga Yoichi, Nakamura Yasuhiro

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2012/04/01 - 2016/03/31

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Segmental venous sampling is essential for diagnosis and localization of aldosterone producing adenomas. In segmental adrenal venous sampling (S-AVS), blood samples are obtained with microcatheters inserted into the target venous tributary. However, it sometimes happen that blood samples cannot be obtained through catheters. In such cases, it is assumed that suction pressure deforms venous wall, then catheter tip is considered to be occluded. To our knowledge, there has been no study concerning hemodynamics in venous catheter blood sampling. The purpose of this study is to simulate the blood flow in venous blood sampling using synthetic very small blood vessel or Computational Fluid Dynamics method and to search the catheter tip shape suitable for the procedure. The prototype of microcatheter whose tip was shaped suitable for S-AVS was created. And then, the performance of the microcatheter was evaluated in an animal study.
Study on the next generation stent construction for cerebral aneurysm

NAKAYAMA Toshio, OHTA Makoto

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)

Category: Grant-in-Aid for Scientific Research (C)

2012/04/01 - 2015/03/31

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In this study, the purpose is the development method construction of the next generation stent for cerebral aneurysm. First, the classification method of cerebral aneurysm based on fluid dynamics using consideration curvature of the parent artery in addition to Aspect Ratio was developed. Therefore, it becomes possible to design of the effective stent using this classification method. The fluid-structural interaction analysis was introduced in the development of stent design method. The vessel wall and cerebral aneurysm wall are varied due to the influence of the blood flow. The simulation accuracy is higher than conventional numerical fluid dynamics analysis and it is possible to develop the stent adapting for cerebral aneurysm. From study results, it is possible to find the development method construction of next generation stent.
Development of minimally-invasive interventional radiological therapy of primary aldosteronism based on adrenal venous sampling.

TAKASE KEI, OOTA Makoto, MORIMOTO Ryou, SEIJI Kazumasa, SATOU Fumitoshi, SATOU Miho

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2011/04/01 - 2014/03/31

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Real-size vascular model including adrenal venous tributaries was generated, which was utilized for simulation of catheterization. Experimental study using bovine adrenal gland showed that 3 insertion patterns of bipolar needles enables complete ablation of adrenal adenoma with 10 to 25-mm in diameter. Adjacent organ with 5-mm intervening adipose tissue was preserved. Initial clinical interventional radiological treatment achieved normalization of plasma aldosterone level and amount in 24-hour urine specimen. Cost-effectiveness of this treatment was also proven.
Time-dependent blood flow analysis with measurement coupled simulation

HAYASE Toshiyuki, SHIRAI Atsushi, OHTA Makoto

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2007 - 2009

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This research was performed to develop a method for accurate reproduction of in vivo blood vessels and blood flow state by computer simulation to give feedback from the measurements of a medical ultrasonic diagnostic equipment even if the blood vessels in vivo conditions are unknown. The goal of this research is to contribute to the elucidation of the mechanism of cardiovascular diseases and treatments by analyzing the time dependence of the human body. Indicated possibilities can accurately assess the cardiovascular diseases of aging new combinations can predict atherosclerosis and vascular stenosis diagnosis indices became clear.
シネマティックアンギオを用いた脳動脈瘤内の血流フローダイナミクス計測法の開発

太田信

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 若手研究(B)

Institution: 東北大学

2006 - 2007

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脳動脈瘤の血管内治療では、血流速度を減少させ、治癒を行うことが一般的となっている。血流速度を測定することは、治療方法の策定および検証に非常に大切である。しかしながら、治療中治療後も含めて血流速度を測定できる方法は今まで皆無であった。本研究では、治療中、治療後も同一の条件で使用する血管造影装置からの連続画像を用いたVortex Center Path line method (VCP)法を考案し、実用プログラムの作成を行い、その有効性を検証した。具体的には,治療の際に用いられる血管造影装置で得られた画像から,流体力学と画像情報処理に基づいた血管造影剤の渦軌跡を追跡することにより,動脈瘤内の血流速度を計測する方法を開発した。このような流体力学の手法と画像処理といった工学的なアプローチを適用したことに本研究の特色がある。本結果は第4回国際イントラクラニアルステント学会(京都)において、「Quantification of Flow in aneurysm for Development of Intracranial Stent」と題して招待講演に選ばれた。さらに、実際の臨床の現場において、脳動脈瘤の発生・成長に関する血流の影響を調べるため、血流数値流体解析との組み合わせ、血流状態を調べる新たな共同研究を行った。この結果は第32回日本脳神経血管内治療学会(神戸)において発表され、演者がポスター賞(銀賞)を受賞するなど、基礎医学だけでなく、実際の臨床現場にも多大な影響与え貢献をした。
Biomedical Engineering Competitive

System: International Joint Research Projects

2001/09 -

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Social Activities 7

第9回CVC 千葉血管障害の原点を考える会

2015/11/04 -

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講演会
みやぎ県民大学

2014/08/29 -

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血液の流れを講演する
宮城県民大学

2009/09/25 -

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血流の流れ
みやぎ県民大学

2009/09/11 -

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みやぎ県民大学で，公開講座を行った
仙台市出前授業

2005/12/19 -

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仙台市立松森小学校に出前授業を行った
仙台市の出前授業

2005/12/15 -

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仙台市立川前小学校に出前授業に行った
みやぎ県民大学

2005/09/08 -

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みやぎ県民大学で，公開講座を行った

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Media Coverage 6

Blue Practice 血管内手技の向上を支援

日刊工業新聞

2022/02/22

Type: Newspaper, magazine
東北大発新興、センサー搭載の血管モデル医師の練習用

日本経済新聞

2022/02/22

Type: Internet
コロナ感染者を車で運ぶにはエアコンは外気導入で窓を閉める東北大学の研究 Myself

khb東日本放送

2022/02/15

Type: TV or radio program
車内の感染リスク･･･運転席を「閉めた方」が有効感染が疑われる家族を乗せ運転する場合は？ Myself

仙台放送

2022/02/09

Type: TV or radio program
Blue Practice 血管内手技の向上

日刊工業新聞

2022/01/17

Type: Newspaper, magazine
感触，実物そっくり歯科向け口腔模型を開発

河北日報

2007/06/04

Type: Newspaper, magazine

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感触，実物そっくり歯科向け口腔模型を開発

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Academic Activities 7

Frontiers

Activity type: Peer review

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査読
Cardiovascular Engineering and Technology

Activity type: Peer review

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査読
PLOS ONE

Activity type: Peer review

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査読
International Journal for Numerical Methods in Biomedical Engineering

Activity type: Peer review

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査読
Evaluation of aneurysm rupture risk based upon flowrate-independent haemodynamic parameters: a multi-centre pilot study

Activity type: Peer review

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査読
Technology and Health care

Activity type: Peer review
日本機械学会学術誌

Activity type: Academic society, research group, etc.

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新学術誌編修委員会委員査読

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Other 40

大動脈瘤用ステントグラフトのインビトロ試験

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大動脈瘤用ステントグラフトのインビトロ試験を行う
骨髄液流れ

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骨髄液の流れをモデル化する
ステント内流れ計測

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ステント内の流れをMRI,PIV,CFDで計測する
歯垢除去法の開発

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歯垢除去法の開発
コイルモデル内ながれの可視化

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コイルモデル内の流れの可視化実験
副腎診カテ吸引試験

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副腎に用いる診カテの吸引能力を調べる
足モデルの開発

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ストッキングの締め付けを測定する足型のモデルを開発する
骨ドリルモデルの開発

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骨のドリル試験に用いる模擬骨の解析
measurement of temperature distribution using ablation catheter with biomodel

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アブレーションカテーテルの生体組織への温度分布測定
analysis of staphylococcal γ-hemolysin heteroheptameric transmembrance pore complex for blood cell weakness

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ブドウ球菌の2成分性毒素γヘモリジンが形成するヘテロヘプタマー膜孔複合体血球脆弱化に関する研究
Measurement of Flow Speed of In Vitro Aneurysm Models with Coils Using Particle Image Velocimetry (PIV)

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コイルが留置された脳動脈瘤モデル内の流れに関する研究
Optimized design of intracranial stent

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脳動脈瘤用ステントの最適化設計
Study on a Catheter Movement with Poly (vinyl alcohol) Hydrogel for the Development of an In-Vitro Tracking System

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カテーテルの挙動に関する研究
Tribology of PVA hydrogel

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PVAハイドロゲルの摩擦特性に関する研究
blood flow analysis for stenosis

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狭窄血流に関する研究
3D Visualization of numerical simulation of blood flow on intracranial stent

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3次元可視化システムを用いた血流数値解析の可視化
The development of oral mucosa model

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歯科模型を開発する
Development of catheter motion capture system

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カテーテルの挙動に関する研究
PIV measurement in cerebral aneurysm with coil

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コイル後の脳動脈瘤内の血流に関する研究
Friction measurement of biomodel

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血管モデルの摩擦に関する研究
Friction measurement of oral mucosa biomodel

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口腔粘膜モデルの摩擦に関する研究
optimization of stent

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ステントの最適化
Development of intracranial stent as flow diverter

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血流阻害用脳動脈瘤用ステントの開発
Instruction of flow simulation in stenosis

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血管狭窄内の血流に関する技術提供
医薬品・医療機器等レギュラトリーサイエンス総合研究事業医療機器・医用材料のリスクアセスメント手法開発に関する研究

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医療機器・医用材料のリスクアセスメント手法開発に関する研究
The development of oral mucosa model

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歯科模型を開発する
Blood flow analysis of carotid

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頸動脈中の血流を測定と数値流体解析で整合性を調べる
validation of blood flow computational simulation

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血流の数値流体解析の整合性を調べる
脳動脈瘤および脳内疾患における手術シミュレーションの研究開発

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脳動脈瘤および脳内疾患における手術シミュレーションについて研究および開発することを目的とする．3次元プリンターを用いた構造創製を目指し，サブミリでの制御を目指す．
collaboration of dental issue

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歯科バイオモデリングに関する共同研究
diffusion of contrast

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脳動脈瘤内の造影剤の拡散についてシミュレーションを行う
heat measurement of nano particle

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ナノ粒子の熱測定を行う
development of esophagus stent with PVA mucosa

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PVA粘膜型食道ステントの開発を行う
collaboration of medical issue

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バイオモデリングの開発
Blood measurement in cerebral aneusyrms by PIV

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PIVによる脳動脈瘤バイオモデリング内の血流測定
biomodelling of cerebral aneurysm

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脳動脈瘤のバイオモデリングを作成する
movment of aneurysm

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動脈瘤の動きについて，測定する
computer simulation of micro catheter

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マイクロカテーテルのコンピュータシミュレーションによる，動作予測を行う．
evaluation of image quality of 4D-CT

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4D-CTの画像評価を行う方法を開発する
biomodelling for arotic aneurysm with PVA hydrogel

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PVAを用いた大動脈瘤のバイオモデリングを開発する

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