Biomedical Information Technology Laboratory

Daming Wei Professor	Wenxi Chen Associate Professor	Xin Zhu Special Researcher

Prof. Wei’s research activity in AY 2008 was focused on: Whole-heart model modeling and computer simulation of ECG VVirtual reality and computer simulation of catheter-base Electrophysiology Study Telemonitoring for telemedicine and telehealth Data processing for brain-computer interface Data mining for walking analysis Biometric Authentication using ECG signals Advanced algorithm for detection of QT prolongation Prof. Chens research activities were focused on developing a series of instrumentation technologies for vital signs monitoring in daily life environment, and applying various data mining algorithms to conduct comprehensive interpretation of multifarious longterm physiological data, in the end, building a scalable healthcare integrated platform SHIP for diversity of applicable domains. Main topics include: Monitoring of heart rate, breath rate and body movement during sleep by an invisible means. Monitoring of body temperature by a wearable device. Monitoring of multiple vital signs based on mobile phones. Integration of an Internet-based system for perpetual data collection and automatic data mining. Dr. Xin Zhu, a postdoctoral researcher, focused his research activity on the computer simulation of heart, the biomedical signal processing for ECG, and the healthcare monitoring systems. In 2008, he conducted the researches on the computer simulation of EPS and ventricular pacing, the refinement of spatial filter for removing muscle noise in the standard 12-lead ECG, and the analysis of long-term data recorded during sleep.

Refereed Journal Papers

[dm-wei-01:2008]	Z. Zhang, A. He, and D. Wei. A Mobile Network-based Multimedia Teleconference System for Homecare Services. Telemedicine and e-Health, 14(2):147–155, March 2008.
	As most research and development for homecare services have focused on providing connections between home and service centers, the goal of the present work is to develop techniques and create realtime communications to connect service centers and homecare workers in mobile environments. A key technical issue for this research is how to overcome the limitation of bandwidth in mobile media and networks. Effort has been made to balance performance of communication and basic demands in telehealth through optimized system design and technical implementation. Implementations using 3G (third generation) FOMA (Freedom Of Mobile multimedia Access) and PHS (Personal Handyphone System) were developed and evaluated. We conclude that the system we developed based on 3G FOMA provides sufficient and satisfactory functions for use in homecare services.
[dm-wei-02:2008, wenxi-01:2008, zhuxin-01:2008]	Wenxi Chen, Xin Zhu, Tetsu Nemoto, Kei’ichiro Kitamura, and Daming Wei. Unconstrained monitoring of longterm heart and breath rates during sleep. Physiological Measurement, 29(2):N1–10, 2008.
	An unconstrained method for the long-term monitoring of heart and breath rates during sleep is proposed. The system includes a sensor unit and a web-based netbox. The sensor unit is set beneath a pillow to pick up the pressure variations on the head induced by inhalation/exhalation movements and heart pulsation during sleep. The measured pressure signal was digitized and transferred to a remote database server via the netbox. A wavelet-based algorithm was employed to detect the heart and breath 　rates, as well as body movement, during sleep. The overall system was utilized for a total six-month trial operation delivered to a female subject. The profiles of the heart and breath rates on a beat-by-beat and daily basis were obtained. Movements during sleep were also estimated. The results show that the daily average percentage of undetectable periods (UPs) during 881.6 sleep hours over a 180-day period was 17.2%. A total of 89.2% of sleep hours had a UP of no more than 25% per day. The profile of the heart rate revealed a periodic property that corresponded to the female monthly menstrual cycle. Our system shows promise as a long-term unconstrained monitor for heart and breath rates, and for other physiological parameters related to the quality of sleep and the regularity of the menstrual cycle.
[dm-wei-03:2008]	E. Ryzhii, K. Fukuda, H. Shimokawa, and D. Wei. Atypical Brugada syndrome: a simulation study with 3D heart model. Japanese Journal of Electrocardiology, vol.29(suppl 1):S–1–86, Jan 2009.
	Brugada syndrome leads to idiopathic ventricular fibrillation with characteristic electrocardiogram findings determined by right bundle block and ST-elevation in the right precordial leads. Recently some cases of Brugada syndrome with J wave in inferior and lateral leads have been reported. In this work we presented the simulation of atypical BS utilizing software based on a whole-heart model. The model heart is composed of approximately 50,000 units and the specialized conduction system is distributed to obtain the excitation sequence resembling normal ventricular depolarization. The normal distribution of action potential waveforms with longest duration on the endocardium and the shortest on the epicardium is used in the model. The heart model is mounted in a homogeneous torso model, and the body surface potential distribution generated by the electric dipoles is calculated using the boundary element method. By setting the action potentials of Brugada cells in different epicardial regions, we calculated 12-lead ECG and body surface potentials which are in good agreement with clinical data. Applying additional electrical stimuli we obtained the induction of ventricular fibrillation in both typical and atypical BS forms. The calculated results confirm possibility of similar electrophysiological basis in both cases, and suggest that BS can also be observed in inferior and lateral precordial leads.

Refereed Proceeding Papers

[dm-wei-04:2008, zhuxin-02:2008]	Xin Zhu, Osamu Okazaki, and Daming Wei. A Computer Simulation of Clinical Electrophysiological Study. In Proceedings of 30th IEEE EMBS Annual Conference, pages 585–588. IEEE Press, Aug. 2008.
	Clinical Electrophysiological Study (EPS) is an important tool to evaluate the electrophysiological property of the heart. In this paper, we present a computer simulation of EPS using a heart model with WPW syndrome of type A. In this simulation, standard pacing protocols, including the atrial extrastimulation, ventricular extrastimulation, incremental atrial pacing, and incremental ventricular pacing, were delivered in the heart model. The corresponding excitation and propagation process of the heart, and the intracardiac electrograms that would be measured with catheter electrodes were computed. We successfully reproduced the EPS tests with the heart model. Typical results included the determination of the refractory period, induction and termination of supraventricular tachycardias, and the localization of accessory pathway. This study demonstrates the feasibility of the computer simulation for the EPS as a potential method for the basic and clinical research on cardiac electrophysiology and EPS.
[dm-wei-05:2008, zhuxin-03:2008]	Xin Zhu, Osamu Okazaki, and Daming Wei. Simulation of EPS based on heart models. In Proceedings of the 23rd Annual Conference of Japanese Heart Rhythm Society, page 169. Japanese Heart Rhythm Society, May 2008.
	Goal: In the clinical arrhythmias, through conducting the Electrophysiological study to analyze the activation propagation in the heart, the doctors can diagnose the conduction disorder and tachycardiac reentry to confirm the necessarity for catheter ablation. On the other hand, the computer simulation of heart is an important method to confirm whether the hypothesis is right. In this research, based on theWei-Harumi model, we realized the computer simulation of EPS. Methods: Based on the clinical findings, we designed a model of heart with WPW syndrome incorporating an accessory pathway at the lateral of the left ventricle. In this model, the refractory period of the accessory was set different in the anterograde and retrograde directions, and the refactory period and conduction velocity of the special conduction system are adaptively modified with the coupling interval. The main EPS protocols, including the basic interval measurement, the extra-stimuli and incremental pacing in the atria and ventricles, were reproduced. Based on the numerical calculation, employing the simulated spatial distribution of membrane potentials and the bi-domain model, we calculated the simulated body surface ECG and intracardiac electrograms. Reults: Using the model of heart with WPW syndrome, we reproduced the RV electrogram with the V deflection due to the early excitation via the conduction of Kent bundle. Through setting the incremental pacing at the HRA, we simulated the Wenchebach rhythms and the His-bundle electrograms with the AH interval prolongation. Then, through setting the retrograde conduction in the Kent bundle, we reproduced the orthodromic reentry, where the activation was conducted from the atrium to the ventricle via the special conduction system in the anterograde direction, and then conducted from the ventricle to the atrium via the Kent bundle. Furthermore, through delivering an extra-stimulus with a coupling interval of 200 msec, we successfully reproduced the termination of an orthodromic type supraventricular reentry with a 270msec’s cycle length. Conclusion: In this research, we reproduced typical electrophysiological phenomena of WPW syndrome and tested the mechanisums of the induction and termination of arrhythmic reentries using the model of heart with an accessory pathway in a virtual platform. Therefore, we can we can set the Kent bundle at the endocardium, where the catheter ablation can be conducted, to test the excitation conduction in the Kent bundle.(in Japanese)
[dm-wei-06:2008]	Bofeng Zhang, Ke Yan, Susu Jiang, and DamingWei. Walking stability analysis by age based on Dynamic Time Warping. In 8th IEEE International Conference on Computer and Information Technology, pages 544–548. IEEE CS, July 2008.
	There are more and more researches on walking stability analysis for health management of elderly people. This study presents a definition and an assessment of human walking stability. Its main objectives are to propose a technique to quantify local dynamic stability, and to study the relationship between walking stability and age in developing an understanding of normal gait. Dynamic Time Warping (DTW) is an algorithm for measuring similarity between two sequences, which is employed to estimate the walking stability based on Fourteen-Linkage (FL) walking model. The walking data were from 58 health subjects aged from 21 to 65, walking on a regular surface. The results show that when walking on a regular surface, the walking stabilities including subject ’s position, velocity and acceleration have some relationship with age.
[dm-wei-07:2008]	Y. Mao, M. Saito, T. Kanno, and D.Wei. Walking pattern analysis and SVM classification based on simulated gaits. In Proceedings of 30th IEEE EMBS Annual Conference. pages 5069–5072. IEEE Press, Aug. 2008.
	Three classes of walking patterns, normal, caution and danger, were simulated by tying elastic bands to joints of lower body. In order to distinguish one class from another, four local motions suggested by doctors were investigated stepwise, and differences between levels were evaluated using t-tests. The human adaptability in the tests was also evaluated.We improved average classification accuracy to 84.50human adaptability is a factor that can cause obvious bias in contiguous data collections.
[dm-wei-08:2008]	Motoki Sakai and Daming Wei. Wavelet shrinkage applications of EEG-ECG-based human-computer interface. In 8th IEEE International Conference on Computer and Information Technology, pages 538–543. IEEE CS, July 2008.
	In many situations where ambulatory monitoring is needed, the electroencephalogram (EEG) and the electrocardiogram (ECG) are desired to be simultaneously used. Therefore, it would be desirable if one can acquire both EEG and ECG signals with a single measurement. One of the key techniques in such kind of application is to separate EEG and ECG using signal processing techniques. In our study, we have confirmed that by applying non-cephalic reference electrode in the EEG recording, it is possible to obtain ECG signals available for signal processing. We also improved the wavelet shrinkage algorithm by performing window operations in approximation level five of wavelet components to successfully separate the EEG components from the ECG signal. Our results showed that the improved normalized power spectrum were accurate in all frequency bands for the EEG components, while the R peak detection for the ECG were 100 % successful in this study.
[wenxi-02:2008]	Wenxi Chen, Masumi Kitazawa, and Tatsuo Togawa. HMM-based Estimation of Menstrual Cycle from Skin Temperature during Sleep. In Proc. of the 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC08), pages 1635–1638, Vancouver, British Columbia, Canada, August 20-24 2008. The IEEE Engineering in Medicine and Biology Society.
	An HMM-based method is proposed to estimate biphasic property in female menstrual cycle. A tiny device is developed to measure skin temperature change during sleep. Data are collected from 30 female participants for 6 months. Raw data are preprocessed to remove obvious outliers and clamped between 34 and 42 degree Celsius. A two hidden states HMM-based algorithm was applied to estimate the biphasic property in menstrual cycle. The results showed that the number of correctly detected menstrual cycle is 159 among 173 in 30 participants during 6 months. Overall sensitivity reaches 92.0%.
[wenxi-03:2008, zhuxin-04:2008]	Xin Zhu, Wenxi Chen, Zunyi Tang, Tetsu Nemoto, and Daming Wei. Automatic Home Care System for Monitoring HR/RR during Sleep. In Proc. of the 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC08), pages 522–525, Vancouver, British Columbia, Canada, August 20-24 2008. The IEEE Engineering in Medicine and Biology Society.
	This paper described an automatic home care system for monitoring HR/RR during sleep. Pressure signal is measured with a completely unconstrained pressure sensor beneath a pillow; then the signal is digitalized and the data are transmitted to a remote server using TCP/IP via a netbox. The data are processed and analyzed with a wavelet-based algorithm to obtain the heart rate and respiration rhythm during sleep. Through analyzing 180 days ’data obtained from a female subject, it was found that this system can be used for daily monitoring heart rate and respiration rhythm during sleep and evaluating the quality of sleep at home.
[wenxi-04:2008, zhuxin-05:2008]	W. Chen, X. Zhu, and T. Nemoto. Analysis and Evaluation of Long-term Heart/Breath Rates during Sleep. In Proc. of the 47th Annual Conference of Japanese Society for Medical and Biological Engineering, pages 900-901, Kobe, Japan, 8-10 May 2008. Japanese Society for Medical and Biological Engineering.
	It have been proved that the variations of heart rate and respiration rhythm are effective for the evaluation of the autonomic nervous system and stress. An automatic measurement and evaluation method, which does not bring about burdens to users, is expected to be developed for daily life use. In this research, we developed a method to put a sensor kit in the pillow to measure the pressure variations from the respiration and heart beat during sleep, and use the internet to transfer and save the digital data to a remote database server automatically. Then the data is processed with a wavelet transform based algorithm to estimate the heart rate and respiration rhythm during sleep in the application server. We collected and analyzed the 881.6- hour’s sleep data from a 30s’ woman for more than 6 months. Although the body movements influenced the measured data, the data in 89.2% of the time during sleep can detected. We also observed that the long-term varition of the average heart rate during sleep is related with the menstrual cycle. (in Japanes

Chapters in Book

[dm-wei-09:2008, wenxi-05:2008, zhuxin-06:2008]

Wenxi Chen, Xin Zhu, Tetsu Nemoto, Daming Wei, and Tatsuo Togawa. Data Mining in Medical and Biological Research, pages 177–208. IN-TECH, Vienna, Austria, 2008. Chapter 11: A Scalable Healthcare Integrated Platform (SHIP) and Key Technologies for Daily Applications

Grants

[wenxi-06:2008]

Wenxi Chen. Grants-in-Aid for Scientific Research（20500601), 2008.

Academic Activities

[wenxi-07:2008]	Wenxi Chen, May 30-31 2008. PC member of the 5th International Conference on Information Technology and Applications in Biomedicine (ITAB 2008), in conjunction with the 2nd International Symposium & Summer School on Biomedical and Health Engineering (IS3BHE 2008), Shenzhen, China
[wenxi-08:2008]	Wenxi Chen, 2008. The Editorial Board for the Open Medical Informatics Journal
[wenxi-09:2008]	Wenxi Chen, 8 July 2008 - 11 July 2008. PC member of IEEE 8th International Conference on Computer and Information Technology University of Technology, Sydney, Australia

Patents

[dm-wei-10:2008]

D. Wei. Method and apparatus to direve ECG on additional leads, July 2008.

Ph.D, Master and Bachelor Theses

[dm-wei-11:2008]	Yuichi Shigeno. Graduation Thesis: Driving simulation by EEG-based BCI, University of Aizu, 2008. Thesis Advisor: Daming Wei
[dm-wei-12:2008]	Ken Inomata. Graduation Thesis: An algorithm for Camera Registration in a Laparoscopic Navigation System, University of Aizu, 2008. TThesis Advisor: Daming Wei
[dm-wei-13:2008]	Yusuke Kikuchi. Graduation Thesis: A Viewer for Laparoscopic Navigation System: a Simulation Study, University of Aizu, 2008. TThesis Advisor: Daming Wei
[dm-wei-14:2008]	Takahiro Sato. Graduation Thesis: An Investigation of Computational Cost in a GPU-Based Environment for Simulation of electrocardiogram, University of Aizu, 2008. Thesis Advisor: Daming Wei
[dm-wei-15:2008]	Akira Nozaki. Graduation Thesis: A Physics-based Simulation for Catheter Manipulation, University of Aizu, 2008. Thesis Advisor: Daming Wei
[dm-wei-16:2008]	Akihiro Haginoya. Graduation Thesis: Development of Wiimote as an Input Device for Catheter Simulator, University of Aizu, 2008. TThesis Advisor: Daming Wei
[dm-wei-17:2008]	Ke Yan. Master Thesis: Age-related Gait Stability Analysis of Healthy Male Subjects, University of Aizu, 2008. Thesis Advisor: Daming Wei

2010 THE UNIVERSITY OF AIZU ALL RIGHTS RESERVED