Early detection and treatment are critical for patients with atrial fibrillation (AF), which is known to increase the risk of stroke and total mortality. In recent years, it has become possible to detect AF using electrocardiography and heart rate sensing. However, detection from pulse waveforms remains a difficult technology. Recent studies have shown that orthostatic hypotension (OH) increases the risk of developing AF. In this study, we focused on the effect of orthostasis on the autonomic nervous system and visualized the pulse wave characteristics of patients with chronic AF during orthostasis by simultaneous measurement of electrocardiogram (ECG) and photoplethysmogram (PPG).

スマートウォッチやスマートリングなどのウェアラブルセンサは，心拍数や身体加速度などの生体情報を計測・収集して管理する健康管理機能を有し，運動や睡眠の客観的評価に役立つデバイスとして普及しつつある．そして，我が国が目指すべき未来の目標として，超早期の疾患予測・予防の実現が提唱されており，未病状態から健康な状態に引き戻すための方法の確立と疾患の発症自体の抑制・予防の推進が重要視されている． 非侵襲手法で生体信号時系列データ得られるウェアラブルデバイスは，人間の健康状態の推定や改善に大きく寄与することが期待され，得られたビッグデータを解析する研究が世界中で進展している．米国ではウェアラブルセンサから得られた皮膚体温，心拍数および関連指標と，COVID-19の特徴である発熱，咳，疲労などの症状発現との関連を観察するビッグデータプロジェクトが発足し，生理学的反応検出と罹患予測のアルゴリズム開発を目的として生体情報の収集が進んでいる(TemPredict Study)．体内ウイルスの早期検出は感染症の封じ込めにも重要であり，とりわけ医療従事者は，早期予測によって蔓延危険性を低減することができる． このように，パンデミックとの戦いに貢献しうる容易計測手法が模索され，生体信号処理を用いた生体ビッグデータ研究も発展しつつある．報告者らは，これまでにウェアラブルセンサから得られた生体信号に機械学習技術を応用して疾患の予兆を捉える複数の研究に着手しており，心疾患や精神疾患，睡眠障害のスクリーニングを行うアルゴリズムの研究開発を行ってきた． 本発表では，COVID-19の推定に関する最新研究について具体的に紹介した上で，生体医工学分野における展開可能性について述べる．

Pleasant or unpleasant feeling stimulated by taste usually expressed to describe the acceptance or rejection of food and beverages intake by a human. Since it stimulates the emotional reactions, therefore it also induces other response such as heart rate variations. Traditional sensory tools used only subjective measurement such as self-report, to estimate the feeling of tasting. This method sometimes failed to show some differences between the pleasant and unpleasant type of feelings unconsciously. Previous unconscious measurement methods used the intrusive technique by placing some sensors in contact with the body, which may affect the results of sensory analysis. This study was conducted to avoid the effects of using contact sensors and validate the contact-less method of monitoring heart rate due to emotional changes by extracting plethysmographic signal from the green component of the video images. The videos were recorded while the subject responded to pleasant, unpleasant and neutral stimuli. The findings indicated that the heart rate was significantly related to taste stimuli that also reflected the subjective feelings. The unpleasant-taste influenced heart rate to increase more compared to pleasant-taste and neutral-taste. This proposed approach can be used to remotely detect the feeling/emotion that not overtly express through facial expression, speech or gestures.

近年，健康管理のためにウェアラブル・センサが普及しつつある．例えば，アップル社のApple Watchの最新バージョンでは，光電脈波計ばかりではなく心電計の機能まで具備している．確かに，ウェアラブル・センサは身体に直接装着するため，常時連続的な生体情報取得が可能である．しかし当然であるが，ウェアラブル・センサは，それを購入して「装着（ウェア）」しなければセンシングできない． 一方，パーソナルコンピュータやスマートフォンに内蔵されているビデオカメラの映像信号から脈波（映像脈波）が得られる．ウェアラブル・センサに比べて映像脈波が決定的に優れているのは，何も身に付けず（ウェア“レス”に），遠隔・非接触的なセンシングができる点である． 本稿では，まず，映像脈波の計測方法とその性質について述べた後，映像脈波の幅広い応用可能性について解説する．すなわち，家庭における風呂・トイレなどでの血圧サージの検出，洗面所の鏡やスマートスピーカーでの応用可能性，あるいは自動車内での運転者のモニタリングについて触れ，最も応用可能性の高いものとして，スマートフォンを使ったクラウドサービスの概念を紹介する． 次に，映像脈波の実用上の課題と限界について述べる．すなわち，映像脈波の最大の弱点が，体動と照度変化に極端に弱いことであり，それぞれに関する対策を紹介するとともに，今後を展望する

The risk of cardiovascular diseases is related to the absolute level of blood pressure as well as its fluctuation while sleeping or during daily activities. To assess the risk, a simpler method to monitor daily blood pressure is desirable. In recent years, there has been a focus on developing a method to obtain pulse waves from video images of the human body. This is a promising technique to acquire biometric information without contact. In this study, we propose a new method to estimate the absolute level of blood pressure by using two video images of human hands captured at different heights from the heart. We focus on the amplitude difference of pulse waves obtained from the video images and derive an equation to estimate blood pressure based on the relationship between the internal pressure and the cross-sectional area of the blood vessel. The accuracy of the estimation was evaluated using data obtained from 5 healthy subjects performing cycling exercises that change their blood pressure. The average value of the root mean square error between the real value and the estimated value was 25.7 mmHg, while that of correlation coefficient was 0.66. There were large individual differences, particularly in the estimation of the absolute value of blood pressure. This result suggests the need for individual correction of the compliance curve, which represents the relationship between the internal pressure and the cross-sectional area of the blood vessel.

近年，ビデオカメラからの映像を用いて非接触で生体情報を取得する研究が盛んに行われている．ヘモグロビンの吸光度が緑色の波長帯域で高いという原理に基づいて，身体映像中の緑色輝度値の変化から脈波（映像脈波と呼ぶ）を計測することができる．本研究では映像脈波を用いて，血圧の絶対値を推定する手法を提案する．映像脈波は血管内の血液量変化を反映するため，血管の断面積と相関していると考えられる．そこで血管内圧と断面積の関係式を用いて，心臓からの高さが異なる2ヶ所で計測した映像脈波の振幅値の比から血管内圧を推定する式を導出した．健常な5名の被験者を対象として，安静とぺダリング運動を交互に行い血圧を変化させる実験を行った．実験の結果，実際の血圧値と推定値の相関係数は平均で0.64，推定値誤差は平均で42.7 mmHgであったが，最も良い被験者では相関係数0.89，推定値誤差は7.15 mmHgであった．誤差の原因としては，提案式に含まれる定数項の値が被験者毎に異なっているためであると考えられることから，今後，この定数値を安定的に求める方法の確立が必要である．

A non-contact measurement method for estimating blood pressure using video pulse waves has been developed. During fluctuation in blood pressure caused by respiratory arrest, the video pulse waves were measured by using a video camera to calculate the pulse transit time difference (PTTD) from a proximal part to a distal part with respect to the heart. Blood pressure was estimated by a multivariate regression model with the PTTD, heart rate and the pulse amplitude (PA) as explanatory variables. It was suggested that the variation among individuals could be suppressed by using correlation between the model parameters and the changes in the PA.

Recently, driving methods for synchronizing ventricular assist devices (VADs) with heart rhythm of patients suffering from severe heart failure have been receiving attention. Most of the conventional methods require implanting a sensor for measurement of a signal, such as electrocardiogram, to achieve synchronization. In general, implanting sensors into the cardiovascular system of the patients is undesirable in clinical situations. The objective of this study was to extract the heartbeat component without any additional sensors, and to synchronize the rotational speed of the VAD with this component. Although signals from the VAD such as the consumption current and the rotational speed are affected by heartbeat, these raw signals cannot be utilized directly in the heartbeat synchronization control methods because they are changed by not only the effect of heartbeat but also the change in the rotational speed itself. In this study, a nonlinear kernel regression model was adopted to estimate the instantaneous rotational speed from the raw signals. The heartbeat component was extracted by computing the estimation error of the model with parameters determined by using the signals when there was no effect of heartbeat. Validations were conducted on a mock circulatory system, and the heartbeat component was extracted well by the proposed method. Also, heartbeat synchronization control was achieved without any additional sensors in the test environment.

BACKGROUND: Radial artery (RA) pulse diagnosis has been used in traditional Asian medicine. Blood pressure (BP) and pulse rate related to heart rate variability (HRV) can be monitored via the RA. The fluctuation in these parameters has been assessed using fast Fourier transform (FFT) analytical methods that calculate power spectra. METHODS: We measured blood flow volume (Volume) in the RA and evaluated its fluctuations. Normal participants (n = 34) were enrolled. We measured the hemodynamics of the right RA for approximately 50 s using ultrasonography. RESULTS: The parameters showed the center frequency (CF) of the power spectrum at low frequency (LF) and high frequency (HF). More than one spectral component indicated that there were fluctuations. The CF at LF for Volume was significantly different from that for vessel diameter (VD); however, it was significantly correlated with blood flow velocity (Velocity). On the other hand, the CF at HF for Volume was significantly different from that for Velocity; however, it was significantly correlated with VD. CONCLUSION: It is suggested that fluctuation in the Volume at LF of RA is influenced by the fluctuation in Velocity; on the other hand, fluctuation in the Volume at HF is influenced by the fluctuation in VD.

<p>Recently, it has been attracting attention that biological signal can be extracted from the changes in skin color tone of facial video image which obtained by an ordinary camera (e.g. web cam or phone camera). The aim of this study is to investigate the changes in features of pulse wave computed from facial image during cardiovascular regulation. In this study, right and left cheeks and lip sides were selected as regions of interest and video images of the ROIs were recorded at a frame rate of 250fps. Pulse waveform of each ROI was extracted from the changes in green color intensity of the ROI. In result, some indices such as difference of pulse transit time between two positions changed significantly under heating and exercising conditions. This result suggests that not only heart rate but also various indices of cardiovascular regulations can be obtained with non-contact from facial video image.</p>

In this study, an easy system for monitoring dynamic blood perfusion patterns and the pulse wave velocity (PWV) has been developed by processing video images of a human body to assess blood circulation for daily management of physical conditions or for detecting persons in poor physical condition in public places. The experiment suggested that this tool can be used to easily evaluate the PWV; however, the obtained value from the video image of the face was about 1/10 of the standard value calculated from thick vessels. This difference may be related to the difference between thick vessels and thin-branched arterioles.

In recent years, a deep convolutional neural network (DCNN) has attracted great attention due to its outstanding performance in recognition of natural images. However, the DCNN performance for medical image recognition is still uncertain because collecting a large amount of training data is difficult. To solve the problem of the DCNN, we adopt a transfer learning strategy, and demonstrate feasibilities of the DCNN and of the transfer learning strategy for mass detection in mammographic images. We adopt a DCNN architecture that consists of 8 layers with weight, including 5 convolutional layers, and 3 fully-connected layers in this study. We first train the DCNN using about 1.2 million natural images for classification of 1,000 classes. Then, we modify the last fully-connected layer of the DCNN and subsequently train the DCNN using 1,656 regions of interest in mammographic image for two classes classification: mass and normal. The detection test is conducted on 198 mammographic images including 99 mass images and 99 normal images. The experimental results showed that the sensitivity of the mass detection was 89.9 % and the false positive was 19.2 %. These results demonstrated that the DCNN trained by transfer learning strategy has a potential to be a key system for mammographic mass detection computer-aided diagnosis (CAD). In addition, to the best of our knowledge, our study is the first demonstration of the DCNN for mammographic CAD application.

In radiation therapy, respiration-induced tumor motion significantly limits the efficiency of the radiation delivery, and brings potential risk to healthy organs and tissues. In order to deliver a sufficient high-dose radiation in adaptive with the tumor motion, a kilo-voltage (kV) X-ray fluoroscopy imaging system has been used to monitor the tumor motion in real-time during the treatment. In this paper, we present a fast and robust tracking algorithm to track deformable lung tumor motion in the kV fluoroscopic image sequence. Given a kV fluoroscopy, the tumor motion is represented by a nonlinear homographic transformation of a pre-defined tumor template. The homographic transformation is then estimated by minimizing a sum-of-squared-difference (SSD) between the template image and the observed image. To improve the computational efficiency, an efficient second-order minimization method is employed to solve the problem of SSD minimization. The experimental results conducted on clinical kV fluoroscopies demonstrated that the proposed method is capable of tracking the tumor motion in real-time and its performance is superior to conventional tracking methods in terms of tracking accuracy and computational cost.

Physiological indices that reflect autonomic nervous activity are considered useful for monitoring peoples' health on a daily basis. A number of such indices are derived from heart rate variability, which is obtained by a radiofrequency (RE) motion sensor without making physical contact with the user's body. However, the bulkiness of RF motion sensors used in previous studies makes them unsuitable for home use. In this study, a new method to measure heart rate variability using a compact RF motion sensor that is sufficiently small to fit in a user's shirt pocket is proposed. To extract a heart rate related component from the sensor signal, an algorithm that optimizes a digital filter based on the power spectral density of the signal is proposed. The signals of the RF motion sensor were measured for 29 subjects during the resting state and their heart rate variability was estimated from the measured signals using the proposed method and a conventional method. A correlation coefficient between true heart rate and heart rate estimated from the proposed method was 0.69. Further, the experimental results showed the viability of the RF sensor for monitoring autonomic nervous activity. However, some improvements such as controlling the direction of sensing were necessary for stable measurement. (C) 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

The maximum cross-correlation coefficient (<i>ρ</i>_max) between blood pressure (BP) and heart rate (HR) variability for frequency components limited to the Mayer wave-related band is useful for the evaluation of baroreflex function. However, continuous BP measurement with an expensive and bulky measuring device is required to calculate <i>ρ</i>_max. This study proposes a simpler method to obtain <i>ρ</i>_max using a green light photoplethysmogram (PPG). A green PPG sensor is less affected by motion artifacts than a near-infrared PPG sensor. In this study, an electrocardiogram, continuous BP, green PPG, and near-infrared PPG were obtained from the subjects. HR, mean BP, and pulse transit time were estimated from the signals, and <i>ρ</i>_max was subsequently calculated. Compared to the <i>ρ</i>_max obtained from the near-infrared PPG signal, the <i>ρ</i>_max obtained from the green PPG signal is closer in value to the <i>ρ</i>_max obtained from mean BP. These results show that the green PPG sensor can be used to estimate baroreflex function instead of using continuous BP measurement.

A cycling wheelchair (CWC) is a rehabilitation tool for hemiplegic patients. In previous studies, we proposed some indices to evaluate the motor function of the paralyzed leg of the patient driving a CWC. In this study, we focused on the involuntary leg abduction while rotating a CWC pedal, and proposed a new evaluation index based on the abduction motion. The leg abduction can be associated with motor dysfunction because it is due to the contracted muscles of the paralyzed leg. The proposed index requires signals from the gyro and accelerometer sensors attached to the shin of a CWC user. Based on these signals, the abduction angle and the knee position were estimated using a Kalman filter and a three-dimensional model of the leg, respectively. The proposed index is defined as the ratio between variances of the first and second main components of the leg motion trajectory. The main components were calculated by the principle component analysis. Experimental results obtained by employing healthy subjects, who imitated the leg abduction, showed that the proposed method is useful for evaluating the differences in the leg abduction patterns.

Many studies have investigated the relationship between mental load and biological signals such as heart rate and blood pressure. In such studies, the experiments involved attaching sensors on the bodies of test subjects to measure biological signals. However, there are concerns regarding the additional psychological stress on the subjects caused by these sensors. To solve this problem, we propose a new non-contact method to measure not only heart rate but also blood pressure variability. In this method, the time delay is calculated between two pulse waves obtained from different parts of a subject's body captured by a video camera. This index is considered to have a negative correlation with blood pressure variability because it approximates the pulse transit time obtained from a photoplethysmograph. The proposed index was calculated from video images of 20 healthy subjects performing the Valsalva maneuver. The results showed that the correlation coefficient between blood pressure and the proposed index was approximately 0.6.

It is important to know about a sudden blood pressure change that occurs in everyday life and may pose a danger to human health. However, monitoring the blood pressure variation in daily life is difficult because a bulky and expensive sensor is needed to measure the blood pressure continuously. In this study, a new non-contact method is proposed to estimate the blood pressure variation using video images. In this method, the pulse propagation time difference or instantaneous phase difference is calculated between two pulse waves obtained from different parts of a subject's body captured by a video camera. The forehead, left cheek, and right hand are selected as regions to obtain pulse waves. Both the pulse propagation time difference and instantaneous phase difference were calculated from the video images of 20 healthy subjects performing the Valsalva maneuver. These indices are considered to have a negative correlation with the blood pressure variation because they approximate the pulse transit time obtained from a photoplethysmograph. However, the experimental results showed that the correlation coefficients between the blood pressure and the proposed indices were approximately 0.6 for the pulse wave obtained from the right hand. This result is considered to be due to the difference in the transmission depth into the skin between the green and infrared light used as light sources for the video image and conventional photoplethysmogram, respectively. In addition, the difference in the innervation of the face and hand may be related to the results.

It is notable that the photoplethysmogram can be extracted by processing the green component of a video signal of a human body taken with a video camera. This is an affordable, remote and non -contact measurement method to obtain not only heart rate but also blood pressure information. in this study, a tool for obtaining the pulse transit time which correlates with blood pressure has been developed. It is expected that this tool can be used to evaluate plural persons' autonomic function using only one video camera.

In radiation therapy, inter- and intra-fractional tumor motions significantly limit the efficiency of radiation delivery, and bring potential risk to healthy organs and tissues adjacent to the tumor during treatment. To deliver a high-dose radiation adapting to the intra-fractional tumor motion, real-time imaging and tracking the tumor motion during the treatment became critical tasks in radiation therapy research. In this paper, we present our recent studies on tracking the respiration-induced lung tumor motion based on kilo-voltage (kV) and mega-voltage (MV) X-ray fluoroscopy systems. Especially, our focus is on developing robust tracking algorithms to track the deformable tumor motion in real-time. For the kV fluoroscopy, a kernel-based method, which is robust against the tumor deformation and low-contrast image quality, is proposed to track the tumor position. In addition, for the MV fluoroscopy, a region-scalable level set method (LSM) is proposed to tracking the tumor boundary. Experimental results conducted on phantom and clinical data demonstrated the effectiveness of our proposed methods.

Markerless tracking of respiration-induced tumor motion in kilo-voltage (kV) fluoroscopic image sequence is still a challenging task in real time image- guided radiation therapy (IGRT). Most of existing markerless tracking methods are based on a template matching technique or its extensions that are frequently sensitive to non-rigid tumor deformation and involve expensive computation. This paper presents a kernel-based method that is capable of tracking tumor motion in kV fluoroscopic image sequence with robust performance and low computational cost. The proposed tracking system consists of the following three steps. To enhance the contrast of kV fluoroscopic image, we firstly utilize a histogram equalization to transform the intensities of original images to a wider dynamical intensity range. A tumor target in the first frame is then represented by using a histogram-based feature vector. Subsequently, the target tracking is then formulated by maximizing a Bhattacharyya coefficient that measures the similarity between the tumor target and its candidates in the subsequent frames. The numerical solution for maximizing the Bhattacharyya coefficient is performed by a mean-shift algorithm. The proposed method was evaluated by using four clinical kV fluoroscopic image sequences. For comparison, we also implement four conventional template matching-based methods and compare their performance with our proposed method in terms of the tracking accuracy and computational cost. Experimental results demonstrated that the proposed method is superior to conventional template matching-based methods.

Super aging society such as Japan would need tele-healthcare systems for home medical care to suppress medical cost inflation. In this situation, we have developed a tele-healthcare system for end-of-life decision at home using a wireless electrocardiograph combined with a smartphone and a sphygmogram signal extracted from an ordinary video camera. The experimental results have indicated that long term monitoring through the smartphone and a server will provide rich information on the patient's terminal status for doctors in remote locations. However, it is necessary to collect many clinical data to predict the timing of end-of-life more precisely.

Increased blood viscosity is closely associated with the risk of cardiovascular and lifestyle-related diseases such as diabetes. Conventional methods of measuring blood viscosity are not suitable for home use. In the present study, we suggested a new estimation method of blood viscosity using photoplethysmography. As an indicator of blood viscosity, we focused on the damping coefficient of a physical model that simulates the movement of a blood vessel. We calculated the damping coefficients from the blood pressure waveforms of a goat with reducing hemoglobin concentrations in the blood. The results suggested that the damping coefficient was correlated with the hemoglobin concentration, which in turn is correlated with the blood viscosity. Thus, the proposed method could possibility be used to measure blood viscosity.

SY-15-SY-16

This paper presents a faster one-dimensional (1-D) phase-only correlation (POC)-based method for estimations of translations, rotation, and scaling in images. The proposed method is to project two-dimensional (2-D) images horizontally and vertically onto 1-D signals, and uses 1-D POCs of the 1-D signals to estimate the translations in images. Combined with a log-polar transform, the proposed method is extended to scaling and rotation estimations. Compared with conventional 2-D and 1-D POC-based methods, the proposed method performs in a lower computational cost. Experimental results demonstrate that the proposed method is capable of estimating large translations, rotation and scaling in images, and its accuracy is comparable to those of the conventional POC-based methods. The experimental results also show that the computational cost of the proposed method is much lower than those of the conventional POC-based methods.

The implantable cardioverter-defibrillator is an effective therapeutic device for preventing death from life-threatening arrhythmias such as ventricular tachycardia and ventricular fibrillation in patients with cardiac diseases. It is important to prevent their recurrence and treat these arrhythmias as early as possible. It is also essential to accurately distinguish among normal sinus rhythm, ventricular tachycardia, ventricular fibrillation, and supraventricular tachycardia. Therefore, in this study, we proposed a classification method that uses multiple regression model based on information extracted from simultaneous intracardiac electrocardiograms, to identify episodes of sinus rhythm, supraventricular tachycardia, and ventricular tachycardia from human intracardiac electrocardiograms. From the results of validation, we confirmed that the proposed method is able to distinguish shockable cardiac rhythms from nonshockable cardiac rhythms based on indices obtained from simultaneous intracardiac electrocardiograms.

A new physiological index (mu(PA)) is proposed to represent the autonomic nervous system (ANS) function. The index mu(PA) is defined as the natural logarithm of the ratio between two different frequency components of the pulsatile amplitude of the photoplethysmogram (PPG) signal. The discrimination ability and the reproducibility of mu(PA) have been compared with other traditional ANS indices. In the experiment, the electrocardiogram, the PPG and continuous blood pressure were measured in 59 healthy young subjects (age 25.7 +/- 6.3) and 86 healthy elderly subjects (age 70.2 +/- 4.1) at rest. The discrimination ability and the reproducibility were evaluated by Cohen's d between young and elderly groups and by the interclass correlation coefficient, respectively. The results showed that the elderly subjects were significantly (p&lt;0.001) lower than young subjects in mu(PA) and a few traditional indices introduced to be compared with mu(PA). Therefore, it suggests that mu(PA) is associated with the decrease in the ANS function accompanied by aging. Moreover, it showed that the discrimination ability and the reproducibility of the proposed index are comparable or larger than those of traditional indices. The proposed index based on the PPG signal will be applied to tele-healthcare systems for monitoring people's health in daily life in combination with the ratio of the standard deviation of the R-R intervals to their average value (CVRR).

Artificial three-dimensional (3D) video technology has generated significant interest in recent years. However, there are concerns about side effects such as eye strain that may result from viewing 3D video images. This visual fatigue is assumed to be related to a mismatch between convergence distance and focal length that occurs while viewing 3D content. In this study, we investigated the relationship between this mismatch and visual fatigue. Two subject groups completed an easy task while viewing a 3D image containing a convergence distance and focal length mismatch, and while viewing an image without such a mismatch. After the task, visual fatigue was evaluated using a flicker test and a simulation sickness questionnaire (SSQ). Experimental results demonstrated that viewing a 3D video image with the mismatch resulted in more visual fatigue than doing so without the mismatch.

The implantable cardioverter-defibrillator (ICD) is an effective therapeutic device for preventing mortality in patients with cardiac diseases caused by life-threatening arrhythmias. The authors previously proposed an algorithm for the detection of life-threatening arrhythmias using a multiple regression model. To enhance the classification accuracy, we have now incorporated a moving average filter and a multiple detection process into the original detection algorithm. The experimental results showed that the proposed method could attain sufficiently high accuracy for all ventricular fibrillation rhythms to be detected precisely. In addition, the cases of false detection of sinus rhythm or supraventricular tachyarrhythmias, which could cause ICD malfunction, have been reduced. (c) 2013 Wiley Periodicals, Inc. Electron Comm Jpn, 96(12): 1-8, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.11585

A cycling wheel chair (CWC) is a pedal-driven wheelchair developed as a personal transportation device for patients with hemiplegia after cerebral stroke. The CWC enables the patient to travel much faster than an ordinary wheel chair and is effective for prevention of disuse syndrome in lower limbs. However, the patients often have impairment of cognitive function as well as motor function. It is dangerous for such patients to ride on the CWC on outdoor roads. To cope with this problem, a virtual reality system for the CWC named "Virtual CWC" was developed. The Virtual CWC can provide safe and space-saving training and test environment for the patients. In the present study, a new scenario of the Virtual CWC has been developed to test the patient's cognitive function with respect to navigation as well as driving skills. The normal subjects' "homing vectors" obtained after riding on the Virtual CWC in three kinds of routes were analyzed, and compared between a young group (26 normal subjects; age 23.9 +/- 2.5) and an elderly group (14 normal subjects; age 69.9 +/- 4.1). As a result, the effect of cooperation between pedaling and steering could be found in the angular error of homing vectors in the case of the elderly group.

The presence of microcalcification clusters (MCs) in mammogram is a major indicator of breast cancer. Detection of an MC is one of the key issues for breast cancer control. In this paper, we present a highly accurate method based on a morphological image processing and wavelet transform technique to detect the MCs in mammograms. The microcalcifications are firstly enhanced by using multistructure elements morphological processing. Then, the candidates of microcalcifications are refined by a multilevel wavelet reconstruction approach. Finally, MCs are detected based on their distributions feature. Experiments are performed on 138 clinical mammograms. The proposed method is capable of detecting 92.9% of true microcalcification clusters with an average of 0.08 false microcalcification clusters detected per image.

To achieve a better therapeutic effect and suppress side effects for lung cancer treatments, latency involved in current radiotherapy devices is aimed to be compensated for improving accuracy of continuous (not gating) irradiation to a respiratory moving tumor. A novel prediction method of lung tumor motion is developed for compensating the latency. An essential core of the method is to extract information valuable for the prediction, that is, the periodic nature inherent in respiratory motion. A seasonal autoregressive model useful to represent periodic motion has been extended to take into account the fluctuation of periodic nature in respiratory motion. The extended model estimates the fluctuation by using a correlation-based analysis for adaptation. The prediction performance of the proposed method was evaluated by using data sets of actual tumor motion and compared with those of the state-of-the-art methods. The proposed method demonstrated a high performance within submillimeter accuracy. That is, the average error of 1.0s ahead predictions was 0.931 +/- 0.055 mm. The accuracy achieved by the proposed method was the best among those by the others. The results suggest that the method can compensate the latency with sufficient accuracy for clinical use and contribute to improve the irradiation accuracy to the moving tumor.

This paper presents a three-dimensional (3-D) volume registration method that uses 3-D phase correlation to estimate the respiration-induced tumor motion in four-dimensional (4-D) thorax computed tomography (CT) for radiation therapy. The proposed method is an extension of 2-D phase correlation method to 3-D volume registration. Given two CT volumes obtained from different respiration stages, the tumor motion is modeled as a translational shift between the volumes. The 3-D phase correlation is obtained from the 3-D inverse Fourier transform of a normalized cross power spectrum of the volumes. The tumor motion along three directions is estimated by locating the highest peak in the 3-D phase correlation. In order to improve the estimation accuracy, we extend the 3-D phase correlation to sub-voxel accuracy. Experimental results demonstrate the effectiveness of the proposed method relative to a conventional 2-D phase correlation-based method.

When we consider the medical economy, the Obesity is one of the leading preventable causes of death worldwide. However, a lot of previous scientific papers reported that 95% of obesity patients would not be able to control their weight by the diet. The surgical operation has been considered to the subjects with severe obesity. But, there is a possibility of complication or comorbidity in surgical operation. Tohoku University started to develop the expanding capsule with transcutaneous energy transmission system (TETS) having the same effect as the surgical operation. The capsule in the stomach will expand mechanically by energy transmission from outsides of the body, when the obesity patients will felt hungry. Small linear drive with folding umbrella type actuator would enable us the expansion of the diet capsules. Satisfactory characteristic of the energy transmission was obtained by the trial model of TETS during animal experiments. Animal experiments with healthy adult goats enabled us the evaluation of the inner stomach pressure time series changes, and feasibility study. Double blind test of the expanding capsule is now under planning. If the expanding capsule diet control system will be embodied, it becomes the gospel of the obese subject. © 2013 IEEE.

In March 11, 2011, worst disaster called Sendai Quake attacked the north east side of Japan. In the disaster area, Tsunami removed the all building, so, we need simple and easy medical equipment. As the portable device, Electric doctor bag has been invented. In the traditional and alternative medicine, a pulse diagnosis is one of the most important diagnostic methods. However, there was no paper in which the medical evidence of a pulse diagnosis was shown. We invented the quantitative diagnosis machine which could carry out a pulse diagnosis scientifically. This machine could perform a pulse diagnosis using three pressure sensors. The pulse diagnosis is reproduced by various pressures being applied to three pressure sensors from external surface. Three experimental series including the experiments using model circulation circuit, an animal experimental series, and a clinical application with pulse diagnosis machine were conducted. Chaos theory was used for the evaluation in the clinical application of the pulse diagnosis machine. At least as for the part, the data which are in agreement with a traditional Chinese medicine by this pulse diagnosis machine are obtained. A part of Chinese medicine may have the scientific basis medically, in future. Scientific evidence may be able to be given to a pulse diagnosis for the first time in the world using invention of this pulse diagnosis machine. © 2013 IEEE.

Cycling is known to be an effective rehabilitation exercise for hemiplegic patients who face difficulty during walking because of stroke or other brain disorders. A cycling wheelchair (CWC) is a useful tool to provide exercise for these patients and improve their quality of life. In previous studies, our group developed a system that allows patients to safely practice driving a CWC in a virtual environment. However, it has been difficult to check their motor performances and determine the effects of the exercise on a daily basis. This study is an exploratory trial for developing a method to evaluate the motor performances of users based on their CWC pedaling patterns. An experiment with some hemiplegic patients and healthy subjects was conducted and their pedaling patterns were analyzed. Results showed a significant difference between the hemiplegic patients and healthy subjects in an index that reflects pedaling balance between the feet. This result indicates a possible method of evaluating the motor performances of users based on their pedaling patterns. © 2013 Norihiro Sugita et al.

We propose a new markerless tracking technique of lung tumor motion by using an X-ray fluoroscopic image sequence for real-time image-guided radiation therapy (IGRT). A core innovation of the new technique is to extract a moving tumor intensity component from the fluoroscopic image intensity. The fluoroscopic intensity is the superimposition of intensity components of all the structures passed through by the X-ray. The tumor can then be extracted by decomposing the fluoroscopic intensity into the tumor intensity component and the others. The decomposition problem for more than two structures is ill posed, but it can be transformed into a well-posed one by temporally accumulating constraints that must be satisfied by the decomposed moving tumor component and the rest of the intensity components. The extracted tumor image can then be used to achieve accurate tumor motion tracking without implanted markers that are widely used in the current tracking techniques. The performance evaluation showed that the extraction error was sufficiently small and the extracted tumor tracking achieved a high and sufficient accuracy less than 1 mm for clinical datasets. These results clearly demonstrate the usefulness of the proposed method for markerless tumor motion tracking.

In this study, a novel virtual walking system has been developed for putting the concept of advocating a positive acceptance of the later stages of life or aging, called smart aging, into practice. An essential core of the system can be found in striking the right balance between virtual and real worlds for old people to use pleasantly and safely. The system consists of a laptop computer, micro-projectors, and a completely new screen system mounted on the walking frame, called "walking frame mounted display (WFMD)." Users can physically walk with pleasure by the virtual reality technology and safely by the WFMD in the virtual environment. Furthermore, the WFMD does not require any sensors to be worn and is sufficiently inexpensive for home use. Comparison of experimental results clearly demonstrates that the real walking in a virtual environment using the WFMD is easier to use for old people than stamping their feet on the "Wii balance board" in the same environment.

The present paper has reported a case study of the "Electronic Doctor's Bag" which is a telemedical tool for home-visit medical services using the mobile communications environment in an isolated island and a disaster area hit by the tsunami. Clinical trials performed for 20 patients around a clinic in Miyako Island indicated that the communication functions of the proposed system were highly evaluated by patients as well as medical staff's. However, the system still has room for further improvement in operability, portability and mobile communication environment. The experience at the shelter in Kesennuma City suggested that mobile healthcare tools such as the proposed system will be strongly required when there are no or only paramedical staffs after leaving of emergency medical staffs.

There are problems associated with providing healthcare for elderly people living in evacuation centers or temporary housing after a big disaster. This paper introduces two telemedicine systems as tools to maintain the quality of the medical care provided for the elderly at such impromptu facilities. One of these is an electronic doctor's bag (eBag), which enables a physician at a clinic or hospital to check the condition of an elderly patient living in an evacuation center or temporary residence based on video images and biological data submitted via the Internet. The other is a tele-echographic archiving system that helps a physician understand ultrasonographic images submitted from a remote location. We discuss the functions of the telemedicine systems needed in a disaster area based on the results of a demonstration experiment carried out with an eBag, in an actual evacuation center.

In this study, we have been developing a health check device, "Pulse Wave Checker" which is used to obtain indices representing the autonomic nervous function based on photoplethysmogram. This device aims at evaluation of the function easily and safely even at temporary houses after the Disaster. A respiratory control task has been used to quantify the effects of the task on the change in the autonomic nervous characteristic. This paper will discuss the adequacy of the proposed method on the basis of experimental results obtained from 71 subjects consisting of old and young groups. As a result, it suggests that a few kinds of indices representing the dynamic characteristics between the pulse transit time and the heart rate can evaluate the change in autonomic nervous function.

This paper proposes a three-dimensional (3-D) phase correlation-based rigid volume registration method for estimation of the lung tumor motion in four-dimensional (4-D) computed tomography (CT). In the lung cancer radiotherapy treatment, the 4-D thorax CT has been used to observe the spatiotemporal tumor motion with the patient's respiration. In the proposed method, the respiration-induced lung tumor motion is approximately modeled as a 3-D translation between two CT volumes obtained from two respiratory stages. A 3-D phase correlation of the two CT volumes is calculated by using the 3-D inverse discrete Fourier transform (IDFT) of the normalized cross power spectrum of the two volumes. The tumor motion values along three directions are estimated by locating the highest peak of the 3-D phase correlation. The experimental results show that the proposed method is capable of estimating the tumor motion with high accuracy and low computational cost.

We propose a new method for accurate detection of architectural distortion that is a typical sign of breast cancer lesions in mammograms and necessary to be detected and diagnosed properly at an early stage for improvement of the survival rate of patients. An essential core of the proposed method is to efficiently extract a new general feature of the architectural distortions whose lesional intensities are not only higher than those of the surroundings as well known, but also often lower. While conventional features such as radial lines and higher intensities are difficult to be extracted and/or insufficient for accurate detection, the candidate area with such a new feature can be extracted accurately by using a difference of Gaussian (DoG)-based filter and after that a thresholding technique can reduce the number of false positives. The detection based on the new feature is expected to be more accurate than conventional ones because it reflects more general characteristics of the lesion. The experimental result using the database commonly tested worldwide shows that performance of the proposed method is superior to those of conventional ones.

For the development of the new therapeutic device for the atrial fibrillation, implantable cooling device using Peltier element was developed in this study. An implantable cooling device had been consisted from Peltier element with transcutaneous energy transmission system (TETS). 1st coil can be contacted from outside of the body, when the patients will feel palpitation. Electrical current will be induced to the implanted 2nd coil. Peltier element will able to cool the surface of the atrium. For the confirmation of the effect of the cooling device, trial manufacture model was developed Animal experiments using six healthy adult goats after animal ethical committee allowance was carried out. Fourth intercostals space had been opened after anesthesia inhalation, and various sensors had been inserted. AF was induced by the electrical current with battery. As the results, AF had been recovered to the normal sinus rhythm after cooling in all six goats. So, this cooling system for the control of AF showed evident effect in these experiments. Smaller size cooling device has been under development aiming at totally implantable type. Catheter type cooling device for the insertion by the use of fiber-scope type is now under planning for the clinical application. This new type device may be able to become good news for the patients with uncontrollable AF

A cycling wheel chair (CWC) is a useful tool to provide physical exercise for patients who face difficulty walking, caused by stroke or other brain disorders. A system has been developed for rehabilitation, which allows patients to practice driving a CWC in a virtual environment. In this study, hardware improvements were developed and methods for evaluating driving skills were investigated to improve the practical application of this system. The hardware was changed to enable users to drive the CWC they were using in their daily lives. In addition, four types of test scenarios that focused on basic and important actions necessary to drive a CWC, such as pedaling and steering, were developed. An experiment with healthy young and elderly persons was conducted to evaluate the validity of the system. Results showed that pedaling and steering skills were improved in both the young and elderly subjects but the improvement patterns differed between them. These results indicate that repeated practice with the proposed system enhances the safety of driving a CWC, particularly for elderly users.

We develop a new prediction method of respiratory motion for accurate dynamic radiotherapy called tumor following radiotherapy. The method is based on a time-variant seasonal autoregressive (TVSAR) model and extended to further capture time-variant and complex nature of various respiratory patterns. The extended TVSAR can represent not only the conventional quasi-periodical nature but also the residual components which cannot be expressed by the quasi-periodical model. Then the residuals are adaptively predicted by using another autoregressive model. The proposed method was tested on 105 clinical data sets of tumor motion. The average errors were 1.28 +/- 0.87 mm and 1.75 +/- 1.13 mm for 0.5 s and 1.0 s ahead prediction respectively. The results demonstrate that the proposed method can outperform the state-of-the-art prediction methods.

The implantable cardioverter-defibrillator (ICD) is an effective therapeutic device for rescuing patients with cardiac diseases from death caused by life-threatening arrhythmias. The authors previously have proposed a detection algorithm of life-threatening arrhythmia with a multiple regression model. In this research, we have developed the algorithm so as to accurately classify cardiac rhythms and to reduce in the computational time with a microcontroller used in the ICD. The experimental results showed that the proposed method kept a high accuracy to detect cardiac rhythms. In addition, the validation of implementation of the proposed algorithm in the microcontroller indicated that the result of detection of cardiac rhythms could be attained within computational time of 60 ms. For the practical application, it is necessary to evaluate the power consumption of the ICD working with the proposed method.

Recently, because of the ubiquitous popularization of home video cameras, countless people have had opportunities to watch video images captured by amateur cameramen. Because of this, concerns have arisen over potential negative impacts on viewer health, such as visually-induced motion sickness (VIMS). To determine the mechanism inducing VIMS and to establish a method of preventing it, it is necessary to understand which types of video scenes are associated with the onset of VIMS. Furthermore, while it is useful to consider viewer self-assessments while watching such scenes, physiological indices can provide even more information because they can be measured second-by-second in real time. However, there is not much knowledge regarding the temporal relationships between the severity of VIMS and its accompanying physiological conditions. In this study, the average mutual information was employed to determine the temporal relationship between subjective evaluation scores (a subject's personal evaluation of his/her own condition) and various physiological indices present when people suffer from VIMS. Our analysis of experimental data found that changes in the two physiological indices, which were respiratory sinus arrhythmia and the maximum cross-correlation coefficient between heart rate and pulse transmission time, had a concordance rate of more than 60% with changes in the severity of VIMS symptoms experienced by test subjects. Furthermore, we determined that it may be possible to detect signs of impending VIMS prior to the development of symptoms by analyzing physiological indices. (C) 2011 Elsevier B.V. All rights reserved.

In traditional Chinese medicine, moxibustion is a local thermal therapy that is used for several conditions. Quantifying the effects of moxibustion therapy has been difficult because the treatment temperature depends on the physician's experience, and the temperature distribution in the target area is not uniform. This prospective observational study aims to quantify the effect of local thermal stimulation to the abdomen. We developed a heat transfer control device (HTCD) for local thermal stimulation. Twenty-four healthy subjects were enrolled and they underwent abdominal thermal stimulation to the para-umbilical region with the device for 20 min. Blood flow volume in the superior mesenteric artery (SMA) and brachial artery (BA), the heart rate and the blood pressure were measured at rest, 15 min after starting thermal stimulation and 10, 20, 30 and 40 min after completing thermal stimulation. Blood flow parameters were measured by high-resolution ultrasound. In the SMA, blood flow volume was significantly increased during thermal stimulation (P &lt; .01), as well as at 10 min (P &lt; .01) and 20 min (P &lt; .05) after stimulation. In the BA, blood flow volume decreased at 40 min after stimulation (P &lt; .01). In conclusion we could quantify the effect of local thermal stimulation with an HTCD and high-resolution ultrasound. Thermal stimulation of the para-umbilical region increased blood flow in the SMA 20 min after stimulation in healthy subjects.

The present paper has proposed two methods for obtaining the linear correlation of the baroreflex system without measurement of blood pressure. One is based on the pulse wave transit time which needs both the electrocardiogram and the photoplethysmogram. The other is based on the photoplethysmogram only. The results from the experiments showed that the effect of habitual exercise and the Valsalva maneuver can be verified quantitatively. The proposed methods are possible to be used for a test of the autonomic nervous function at home.

Background: Pulse diagnosis of the peripheral artery is an important technique in Traditional Chinese Medicine, where, in acupuncture therapy, the treatment is adjusted according to the observed changes of the pulse. We investigated the change of blood flow in the peripheral artery and the cardiac index during acupuncture treatment. Objectives: The aim of this study is to explore the effect of acupuncture on radial and brachial artery blood flow volume and the cardiac index in healthy subjects. Methods: Eighteen (18) healthy volunteers were enrolled. Acupuncture was performed bilaterally on LR-3 with manual rotation of the needles. The blood pressure and heart rate were measured at rest and 180 seconds after acupuncture. Radial and brachial artery blood flow volume was monitored continuously by an ultrasound with an echo-tracking system. Cardiac index was measured by impedance cardiography. The hemodynamic parameters were measured before, during, and 30, 60, 180 seconds after acupuncture. Results: The peripheral artery blood flow volume decreased significantly during acupuncture (radial; p&lt;0.01, brachial; p&lt;0.05) but increased at 180 seconds after acupuncture (radial; p&lt;0.05, brachial; p&lt;0.05) compared with before acupuncture. The cardiac index did not change significantly after acupuncture, but systemic vascular resistance index significantly decreased (p&lt;0.05). Conclusions: The present study showed that radial and brachial artery blood flow volume decreased immediately during acupuncture on LR-3 acupoint, but increased at 180 seconds after acupuncture. This reaction is attributed to the change in peripheral vascular resistance.

Background: Assessment of the radial pulse by palpation (pulse diagnosis) is an important diagnostic technique in Traditional Chinese Medicine (TCM), but the changes of blood flow volume in the radial artery during and after acupuncture are unknown. Objective: The aim of this study was to explore the changes of radial artery blood flow volume during and after acupuncture in healthy subjects. Design: This study was conducted as a pilot study utilizing a one-group intervention design. Setting: The study was conducted at a TCM outpatient clinic of Tohoku University Hospital. Participants: Twenty-six healthy volunteers participated in the study. Intervention: Acupuncture was performed at LR-3 bilaterally with manual rotation of the needles. Outcome Measures: Blood pressure was measured at rest and 180 seconds after acupuncture. Radial artery hemodynamics were monitored continuously with a high-resolution ultrasound echo-tracking system. The vessel diameter and blood flow volume of the right radial artery and heart rate were measured at rest, before acupuncture, during acupuncture, and 30, 60, and 180 seconds after acupuncture. Results: The systolic and diastolic diameter of the radial artery did not significantly change. Radial artery blood flow volume decreased significantly during acupuncture (mean +/- SD, 0.16 +/- 0.11 mL/sec per m(2); P &lt; .01) compared with baseline (0.43 +/- 0.27 mL/sec per m(2)), but was increased at 180 seconds after acupuncture (0.54 +/- 0.28 mL/sec per m(2); P &lt; .01). Conclusions: The present study showed that radial artery blood flow volume decreased immediately during acupuncture at the LR-3 acupoint, but was increased at 180 seconds after acupuncture.

Background: In traditional Japanese and Chinese medicine, warming the abdomen with moxibustion or herbal medicines has been used for various diseases. However, the effects of these therapies on hemodynamics have not been clear. We clarify the physiological effects of these therapies on the superior mesenteric artery (SMA) blood flow. Participants and Methods: 28 healthy male volunteers were randomly assigned to groups A and B. Group A (n = 14) underwent local thermal stimulation of the paraumbilical region for 20 min at a temperature of 40 degrees C; this simulated the heat and mechanical pressure effects of moxibustion. Group B (n = 14) took the herbal medicine Daikenchuto (TJ-100; 5.0 g) with distilled water. As a control, group C (n = 14) took distilled water alone. Blood flow volume in the SMA was measured by ultrasound from rest to 50 min after the start of each intervention. Results: The SMA blood flow volume increased significantly between 10 to 40 min after the start of thermal stimulation (p &lt; 0.05), and it also increased significantly between 10 to 50 min after administration of TJ-100 (p &lt; 0.01) as compared to the resting volume. However, SMA blood flow volume did not change significantly after administration of water alone. There was no significant difference in SMA blood flow changes between groups A and B. Conclusions: The results suggest that one of the physiological effects of warming the abdomen according to a traditional concept in thermal stimulation and herbal medicine is an increase of SMA blood flow volume.

To analyze the human baroreflex function noninvasively, a beat-by-beat blood pressure signal is often measured by tonometry or plethysmogram using continuous blood pressure sensors. However, these sensors are too expensive and bulky to be used for home healthcare or telemedicine. On the other hand, it is well known that the pulse transmission time (PTT) is strongly correlated with the beat-by-beat blood pressure, especially in the Mayer wave-related frequency band (0.05-0.15 Hz). To obtain a new physiological parameter with a higher correlation with blood pressure in this band compared with that obtained using the PTT alone, we proposed the samephase temporal difference (SPTD) based on electrocardiogram and photoplethysmogram signals. By examining 94 healthy subjects using a combination of SPTD and conventional PTT, it was revealed that the correlation with blood pressure for 25 subjects could be improved using the SPTD instead of the PTT, by applying the criterion of the ratio of their powers. However, for 7 subjects, the correlation decreased. © 2010 International Symposium on Artificial Life and Robotics (ISAROB).

It is well-known that visually-induced motion sickness (VIMS) is caused by image motion. Therefore it is important to clarify the relationship between image motion and the change in discomfort level. However, it is difficult to know the quick change in the level of discomfort during watching actual video image. The authors have proposed a method of interpolation for the subjective score, which has low time and quantitative resolutions, by using physiological parameters. The model which represents the change in subjective score of VIMS was expressed as multiple regression equations in which input parameters are cardiovascular indices such as heart rate variability. In this study, the model which represents the relation between global motion vectors of a video image and estimated subjective score was identified as ARX model. The results indicated that the simple ARX model can estimate the change in subjective score from global motion vectors.

Daikenchuto is a traditional herbal medicine that is used for the treatment of cold feeling in the abdomen, while Orengedokuto, also a traditional herbal medicine, is used for treating inflammatory and ulcerative diseases affecting internal organs. However, the effects of these herbal medicines on cardiac output (CO) and intestinal blood flow have never been investigated. This examiner-blinded randomized crossover study intended to clarify the influence of Daikenchuto and Orengedokuto on CO and blood flow volume in the superior mesenteric artery (SMA). Fourteen healthy men (35 +/- 7 years old) were randomly assigned to two groups: group A and group B. Initially, all subjects were given 50 ml of water orally. After 7 days, subjects in group A were given 5.0 g of Daikenchuto, and 7 days later they were given 2.5 g of Orengedokuto. These herbal medicines were given to group B subjects in the reverse order. CO and SMA blood flow volume were measured from rest to 90 min after the administration of water or each medicine. There was a significant increase in SMA blood flow volume after the administration of Daikenchuto, compared to water alone (p &lt; 0.05) and Orengedokuto (p &lt; 0.05). SMA blood flow volume was significantly increased between 5 and 90 min after administration of Daikenchuto (p &lt; 0.01) compared to the resting state. However, there was no significant change in CO after the administration of either agent. The present study indicates that Daikenchuto increases SMA blood flow volume without increasing CO.

It is well known that the baroreflex system is one of the most important indicators of the pathophysiology in hypertensive patients. We can check the sensitivity of the baroreflex by observing heart rate (HR) responses; however, there is no simple diagnostic method to measure the arterial behavior in the baroreflex system. Presently, we report the development of a method and associated hardware that enables the diagnosis of baroreflex sensitivity by measuring the responses of both the heart and the artery. In this system, the measurements are obtained by monitoring an electrocardiogram and a pulse wave recorded from the radial artery or fingertip. The arterial responses were measured in terms of the pulse wave velocity (PWV) calculated from the pulse wave transmission time (PTT) from the heart to the artery. In this system, the HR change corresponding to the blood pressure change in time series sequence was observed. Slope of the changes in blood pressure and HR indicated the sensitivity of the baroreflex system of the heart. This system could also measure the sensitivity of the baroreflex system of an artery. Changes in the PWV in response to the blood pressure changes were observed. Significant correlation was observed in the time sequence between blood pressure change and PWV change after calculating the delay time by cross-correlation. The slope of these parameter changes was easily obtained and it demonstrated the sensitivity of the baroreflex system of an artery. We evaluated this method in animal experiments using rotary blood pump (RBP) with undulation pump ventricular assist device, and PTT elongation was observed in response to increased blood pressure with RBP assistance. Furthermore, when tested clinically, decreased sensitivity of the baroreflex system in hypertensive patients was observed. This system may be useful when we consider the ideal treatment and follow-up of patients with hypertension.

Sendai, Japan

Visual environments are evolving rapidly along with the popularization of high resolution and wide field-of-view displays. However, there is a concern that these environments may give negative effects oil viewers' health such as visually-induced motion sickness (VIMS). previous studies reported that some physiological indices were useful to assess the effect of visual stimulation. However, we have little knowledge about temporal relationship between the severity of sickness and the change in the physiological indices. In this study, the average mutual information has been employed to investigate this relationship. The analysis of experimental data has suggested that there is a possibility to detect a sign of VIMS prior to the development of symptoms of VIMS with the physiological indices.

The maximum cross-correlation coefficient rho(rnax) between blood pressure variability and heart rate variability, whose frequency components are limited to the Mayer wave-related band, is a useful index to evaluate the state of the autonomic nervous function related to baroreflex. However, measurement of continuous blood pressure with an expensive and bulky measuring device is required to calculate rho(max). The present study has proposed an easier method for obtaining rho(max) with measurement of finger photoplethysmography (PPG). In the proposed method, independent components are extracted from feature variables specified by the PPG signal by using the independent component analysis (ICA), and then the most appropriate component is chosen out of them so that the rho(max) based on the component can fit its true value. The results from the experiment with a postural change performed in 17 healthy subjects suggested that the proposed method is available for estimating rho(max) by using the ICA to extract blood pressure information from the PPG signal.

Text book in all medical school showed that the baroreflex system is one of the most important regulatory systems. When blood pressure increases, heart rate decrease and an artery is dilated with the baroreflex system. By decrease of cardiac output and arterial resistances, blood pressure returns to the normal value. However, there is no diagnostic method, which can measure the sensitivity of a baroreflex system of the artery by the simple methodology. We had challenged invention of the new machine, which could diagnose the sensitivity of the baroreflex system of not only a heart, but also an artery. In this system, the measurement sections are only an electrocardiography (ECG) and peripheral pulse wave. These time series is inputted into a personal computer system, and analyzed quantitatively. Responses of the artery were measured with pulse wave velocity (PWV) calculated from pulse wave transmission time from heart to an artery. In this system, the heart rate change corresponding to the blood-pressure change in time series sequence is observed. Delay time was measured by the cross correlation function. Slope of the blood pressure (BP) change and heart rate (HR) change showed the sensitivity of the baroreflex system of heart. Furthermore, this system can measure the sensitivity of the baroreflex system of an artery. Change of PWV in response to the BP change was observed. We found that significant correlation was observed in the time sequence between BP change and PWV change after delay time calculated from cross correlation. Clinical research was started through allowance of the Ethics Committee. Decreased sensibility in the hypertensive patient's baroreflex system was observed as a result of the clinical research. Furthermore, alteration of the baroreflex sensitivity before and after the drug administration was evaluated. For example, Azelnidipine, Calcium antagonists improved the baroreflex sensitivity of the artery in several cases. This system may be useful for the follow up of the hypertensive patients

Recent advances in video and computer graphics technologies have been accelerating creation of novel visual images including complex and intensive motion of the visual point. However, there are concerns about adverse effects of these images on humans such as visually-induced motion sickness (VIMS). To evaluate the effects of VIMS, the present study has analyzed the linearity of the baroreflex system and that of the mechanical hemodynamic system by using causal coherence functions. The causal coherence functions have a capability of calculating linear correlation between two systems independently even if the systems are connected with each other to compose a closed-loop system. In the experiment, healthy human subjects' heart rate and continuous blood pressure were measured to obtain the causal coherence functions when the subjects were watching an unstable video image. The results showed that there were significant differences in the causal coherence functions as well as the traditional coherence function between the sick and the well groups and that the hemodynamic system was mainly disturbed by VIMS rather than the baroreflex system. These findings suggest that the causal coherence functions of the two systems and the traditional coherence function of the whole system gave different information from one another. This fact implies that the causal coherence functions will be useful and objective means to quantify VIMS as functions of time. (c) 2007 Elsevier B.V. All rights reserved.

In general, it is difficult to compare biological reactions to some kind of stimulation among subjects on the basis of a single physiological parameter such as heart rate variability because there is a large individual variability in its values. A solution to this problem is to utilize the correlation between physiological parameters. In previous works, the maximum cross-correlation coefficient between heart rate and blood pressure variabilities changed when subjects were strongly affected by visual stimulation. In the present work, this index was compared with a traditional one associated with the arterial baroreflex gain to investigate the mechanism of the change in the index. Resting heart rate and continuous blood pressure of twenty-eight healthy adults were measured for five minutes and analyzed. The results showed that these two indices changed similarly to each other while there was little correlation in the mean value between them. Furthermore, the lag time from blood pressure variability to heart rate variability was inversely correlated with the traditional index.

A human watching a swaying image displayed on a wide-field display or screen sometimes suffers from visually-induced motion sickness (VIMS) that causes symptoms related to the autonomic nervous system such as nausea, vomiting, and dizziness. Previous studies indicated that the maximum cross-correlation coefficient (p..,) between blood pressure and heart rate, whose frequency components were limited to the neighborhood of 0.1Hz, was a useful index to evaluate the effects of VIMS on humans. The present study proposed a new method for obtaining p,with measurement of neither continuous blood pressure nor ECG but using only finger photoplethysmography (PPG). In this study, heart rate was obtained from the foot-to-foot-interval of the PPG signal, and blood pressure-related and event-related pieces of information were obtained from the parameter extracted from using the independent component analysis. The adequacy of the proposed method was evaluated by two experiments with the Valsalva maneuver and with presentation of a swaying video image. The experimental results have shown that the proposed method could extract the independent component related to blood pressure and an event signal of Valsalva maneuver. In addition, the effects of VIMS could be estimated with the independent component.

In order to investigate the effect of visually-induced motion sickness in actual video images, this study proposes a method of interpolation for the subjective score, which has low time and quantitative resolutions, by using physiological parameters. The model which represents the change in subjective score of VIMS was expressed as multiple regression equations in which input parameters are cardiovascular indices such as heart rate variability. The estimation results indicated that the model can represent, in higher resolution, the change in the subjective score of the subjects who have induced nausea.

Background: Taking advantage of developed image technology, it is expected that image presentation would be utilized to promote health in the field of medical care and public health. To accumulate knowledge on biomedical effects induced by image presentation, an essential prerequisite for these purposes, studies on autonomic responses in more than one physiological system would be necessary. In this study, changes in parameters of the pupillary light reflex and cardiovascular reflex evoked by motion pictures were examined, which would be utilized to evaluate the effects of images, and to avoid side effects. Methods: Three stereoscopic video movies with different properties were field-sequentially rear-projected through two LCD projectors on an 80-inch screen. Seven healthy young subjects watched movies in a dark room. Pupillary parameters were measured before and after presentation of movies by an infrared pupillometer. ECG and radial blood pressure were continuously monitored. The maximum cross-correlation coefficient between heart rate and blood pressure rho(max), was used as an index to evaluate changes in the cardiovascular reflex. Results: Parameters of pupillary and cardiovascular reflexes changed differently after subjects watched three different video movies. Amplitudes of the pupillary light reflex, CR, increased when subjects watched two CG movies ( movies A and D), while they did not change after watching a movie with the real scenery ( movie R). The rho(max) was significantly larger after presentation of the movie D. Scores of the questionnaire for subjective evaluation of physical condition increased after presentation of all movies, but their relationship with changes in CR and rho(max) was different in three movies. Possible causes of these biomedical differences are discussed. Conclusion: The autonomic responses were effective to monitor biomedical effects induced by image presentation. Further accumulation of data on multiple autonomic functions would contribute to develop the tools which evaluate the effects of image presentation to select applicable procedures and to avoid side effects in the medical care and rehabilitation.

Background: Computer graphics and virtual reality techniques are useful to develop automatic and effective rehabilitation systems. However, a kind of virtual environment including unstable visual images presented to wide field screen or a head mounted display tends to induce motion sickness. The motion sickness induced in using a rehabilitation system not only inhibits effective training but also may harm patients' health. There are few studies that have objectively evaluated the effects of the repetitive exposures to these stimuli on humans. The purpose of this study is to investigate the adaptation to visually induced motion sickness by physiological data. Methods: An experiment was carried out in which the same video image was presented to human subjects three times. We evaluated changes of the intensity of motion sickness they suffered from by a subjective score and the physiological index rho(max), which is defined as the maximum cross-correlation coefficient between heart rate and pulse wave transmission time and is considered to reflect the autonomic nervous activity. Results: The results showed adaptation to visually-induced motion sickness by the repetitive presentation of the same image both in the subjective and the objective indices. However, there were some subjects whose intensity of sickness increased. Thus, it was possible to know the part in the video image which related to motion sickness by analyzing changes in. max with time. Conclusion: The physiological index,. max, will be a good index for assessing the adaptation process to visually induced motion sickness and may be useful in checking the safety of rehabilitation systems with new image technologies.

To quantify the effect of visually-induced motion sickness on the autonomic nervous system, the authors previously proposed a new physiological index P a representing the maximum cross-correlation coefficient between blood pressure variability and heart rate variability whose frequency components are limited to the Mayer wave band. However, rho(max) requires measurement of continuous blood pressure with an expensive and bulky measuring device. In the present study, an easier method for obtaining rho(max) With measurement of neither continuous blood pressure nor ECG but using finger photoplethysmography (PPG) only has been developed. A blood pressure-related parameter was extracted from the PPG by using the independent component analysis. Two experiments in which subjects performed the Valsalva maneuver and then they watched a swaying video image were carried out to evaluate the adequacy of the proposed method. The experimental results have shown that the proposed method worked successfully as good as the conventional method. This means that the proposed method can contribute to increase in the number of subjects because multiple subjects can be used even in a single experiment.

To evaluate the effects of visually-induced motion sickness that induces symptoms related to the autonomic nervous activity, we proposed a new method for obtaining the physiological index p(max), which represents the maximum cross-correlation coefficient between blood pressure and heart rate, with measurement of neither continuous blood pressure nor ECG but using finger photoplethysmography only. In this study, a blood pressure-related parameter was obtained using the independent component analysis of finger photoplethysmography. Two experimental trials in which subjects performed the Valsalva maneuver and then they watched a swaying video image were carried out to evaluate the adequacy of the proposed method. The experimental results have shown that the proposed method worked successfully as well as the conventional method.

Visual images including intensive motions and the experience of virtual reality sometimes induce visually-indeuced motion sickness (VIMS). There are few studies that have objectively evaluated the effects of repetitive exposures to these stimuli on humans. In this study, an experiment was carried out in which the same video image was presented to human subjects three times. We evaluated changes of the intensity of VIMS they suffered from with a subjective score and a physiological index, p(max), which is defined as the maximum cross-correlation coefficient between heart rate and pulse wave transmission time and is considered to reflect baroreflex function. The results showed that the adaptation to VIMS could be represented by a decrease in the objective index pm. as well as the subjective wore. On the contrary, however, some subjects' p(max) increased in a few similar time regions at every trial. This fact suggests that we can specify the part of the video image which is closely related to VIMS by analyzing the change in p(max) with time.

The authors have proposed a new physiological index rho(max) which is the maximum cross-correlation coefficient between blood pressure and heart rate whose frequency components are limited to the Mayer wave-band (0.04-0.15Hz). The advantages of this index are small individual difference and high reproducibility compared with other physiological indices which are calculated independently single cardiovascular measurements. The previous study showed that the index rho(max) is possible to assess visually-induced motion sickness. However, the relation between the proposed index and autonomic nervous activity has not been clarified yet. In this study, the change in rho(max) during sympathetic or parasympathetic blockage has been investigated in comparison with conventional indices in an animal experiment. The results have indicated that rho(max) does not have information on parasympathetic nerve activity but sympathetic one.

To assess the effect of visually-induced motion sickness quantitatively, a swaying motion picture was shown to 55 subjects, and their maximum cross-correlation coefficient rho(max) between Mayer wave-related component in blood pressure variability and that in heart rate variability was analyzed. The physiological index rho(max) reflects the state of baroreflex function governed by the autonomic nervous system. In the case of the subject group who felt motion sickness, decrease in rho(max) could be observed at two positions in time, i.e., around one minute and around ten minutes after the beginning of the presentation. Such biphasic response can lead to the hypothesis that the symptom caused by visually-induced motion sickness can be divided into two parts: the reflective response to avoid the unpleasant visual image and the cumulative symptom corresponding to feeling of sickness. To verify this hypothesis, an unpleasant video image including surgical operation and no swaying scene was presented to the same subjects. The comparison between the swaying image and the unpleasant image showed that the responses of rho(max) were partly similar to each other in the case of the subject group with high self-evaluated susceptibility to motion sickness.

The human watching moving images displayed on a wide-field display or a screen sometimes suffers from visually-induced motion sickness (VIMS) that induces symptoms related to the autonomic nervous system such as nausea, vomiting and dizziness. The previous study indicated that the maximum cross-correlation coefficient (P-) between blood pressure variability (BPV) and heart rate variability (HRV) whose frequency components are limited to the neighborhood of 0.1Hz is a useful index to evaluate the effects of VIMS on humans [1]. The present study has proposed a new method for obtaining rho(max) with measurement of neither continuous blood pressure nor ECG but using only finger photoplethysmography. The adequacy of the proposed method was evaluated on the basis of comparison with the conventional method. An experiment in which multiple subjects were simultaneously watching the same swaying video image was carried out. The experimental result has shown that the proposed method worked successfully as well as the conventional method.

The human watching moving images displayed on a wide-field display or screen sometimes suffers from the visually-induced motion sickness (VIMS) that induces symptoms related to the autonomic nervous system such as nausea, vomiting, and dizziness. The previous study indicated that the maximum cross-correlation coefficient (p(max)) between blood pressure and heart rate whose frequency components are limited to the neighborhood of 0.1Hz is a useful index to evaluate the effects of the VIMS on humans [1]. The present study has proposed a new method for obtaining p(max) with measurement of neither continuous blood pressure nor ECG but using only finger photoplethysmography. The adequacy of the proposed method was evaluated on the basis of comparison with the conventional method. An experiment in which multiple subjects were simultaneously watching the same swaying video image was carried out. The experimental result has shown that the proposed method worked successfully as well as the conventional method.

To assess the effect of acupuncture on the human, 17 healthy volunteers participated in a double-blind randomized crossover clinical trial using real-needle and no-needle seals. In this study, by using systolic blood pressure variability (SBP) and heart rate variability (HR), not only coherence function (K) between SBP and HR but also two causal coherence functions: K-SBP -&gt; HR(2) from SBP to HR and K-HR -&gt; SBP(2) from HR to SBP were introduced to divide causal linearity of the cardiovascular system regarded as a closed-loop system. K-2 represents total linearity of the system. K-SBP -&gt; HR(2) and K-HR -&gt; SBP(2) correspond to the baroreflex system and the mechanical hemodynamics, respectively The results showed that K2(SBP -&gt; HR) over the low frequency band (0.04-0.15Hz) underwent a lot of change in real-needle acupuncture but did not in no-needle acupuncture. And there was difference in K-HR -&gt; SBP(2) over the high frequency band (0.15-0.45Hz) immediately after the stimulation of acupuncture. These results have never been obtained from conventional methods dealing with a cardiovascular system as an open-loop system.

To evaluate the biological effects of visual stimulation on multiple subjects watching a same image, a more compact and low-cost device measuring both ECG and photo-plethysmogram was developed. On the basis of these physiological parameters, the maximum cross-correlation coefficient, rho(max), from pulse wave transmission time to heart rate could be calculated. This index reflects the activity of the autonomic nervous system and is considered as a good index for evaluating the effect of visual stimulation on humans. The result of simultaneous experiment with 6 subjects watching a video image taken by an intentionally swaying handy camera has shown that rho(max) of almost all subjects decreased in the latter part of the video image and that p(max) of the subjects who felt motion sickness strongly decreased after watching the video image at a time.

To quantitatively assess the effect of visually-induced motion sickness, a swaying motion picture was shown to 55 subjects, and their maximum cross-correlation coefficient (ρmax) between Mayer wave-related component in blood pressure variability and that in heart rate variability was analyzed. The physiological index ρmax reflects the state of baroreflex function governed by the autonomic nervous system. In the case of the subject group with extremely high total score in the simulator sickness questionnaire (SSQ), the decrease in ρmax could be observed at two positions in time, i.e., around one minute and around ten minutes after the beginning of presentation. Such biphasic response can lead to the hypothesis that the symptom caused by visually-induced motion sickness can be divided into two parts: the reflective response to avoid the unpleasant visual image and the cumulative symptom corresponding to feeling of sickness. To verify this hypothesis, an unpleasant video film including surgical operation and no swaying scenes was presented to the same subjects. The comparison between the swaying video and the unpleasant video showed that the responses of ρmax were partly similar to each other in the case of the subject group with high self-evaluated susceptibility to motion sickness.

To evaluate the effects of visual stimulation on humans by using the physiological index which can be obtained from a compact and low-cost device, the maximum cross-correlation coefficient from pulse wave transmission time (PTT) to heart rate was introduced. This index was compared with the similar index based on blood pressure in place of PTT in the experiment in which 51 subjects were watching video image to induce motion sickness.

The maximum cross-correlation coefficient from blood pressure to heart rate, rho(max) is a good index for evaluating the effects of visual stimulation on the human. However rho(max) needs a considerably expensive and bulky equipment to measure continuous blood pressure. In the present study, a more compact and cheaper device measuring arterial pulse wave transmission time (PTT) in place of blood pressure has been developed to carry out the simultaneous experiment with multiple subjects watching comfortable or uncomfortable images.

As a basic approach to realization of the real-time image generation that re degrees ects physiological and psychological state, in this study, an auditory biofeedback system mediated by the cross-correlation coe+/-cient 1/2(max) from blood pressure to heart rate has been developed. First, a personal computer system that can calculate 1/2(max) in real time has been developed. Next, a feedback loop has been added to the system so that the magnitude of a noisy sound presented to the subject can be changed according to 1/2(max). The results obtained from the experiments using this system indicated that the auditory biofeedback loop mediated by 1/2(max) can be realized. However, the (-)ne tuning of the controller in consideration of individual di(R)erence is required for establishing a su +/- ciently stable feedback.

To find a new physiological index for quantitative evaluation of the effects of visual stimuli on the human, blood pressure and heart rate of 33 subjects watching two or three dimensional video image were analyzed. The experiments have shown that the maximum cross-correlation coefficient rho(max) from blood pressure to heart rate, whose frequency components were limited to the neighborhood of 0.1Hz, could well reflect the human emotional reaction to visual stimuli. It has also significantly been shown that three dimensional display yielded smaller rho(max) than two dimensional one and that the subjects who previously reported their proneness to motion sickness had smaller rho(max) than those who did not.