Though palpation has long been one of major medical examinations in Oriental medicine, the evaluation of information gained from it depends so much on subjective judgement of each therapist that diagnosis by palpation are often inconsistent. From palpation, a therapist not only feels the hardness, stiffness or flatulence of the place he palpates, but also judges how the hardness of the same point changes as he pushes the body with his fingers. We modeled a bioelasticity system on therapists “pushing” action, in which hardness of the points with different depths in body can be measured. And we made experiments to see how the different “pushing” actions affect measurement. From statistical discussion on the results obtained through experiment, we decided the most reproducible and clinically useful way of “pushing.” In this study, we also tried to visualize the inner structure of the model in which jerry rings of different hardness are stratified.

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We have developed a new method for estimation of breathing frequency using spectrum analysis of fluctuation of R wave amplitude. In this article, we introduced the algorithm for estimation of breathing frequency and examined a reliability of that for five healthy subjects. In the first experiment, subjects controlled their respiration at six patterns of frequencies: 0.10, 0.17, 0.25, 0.33, 0.50Hz and breath holding as a reference value. Each of breathing frequencies was continued for 2 minutes. Electrocardiogram was measured continuously during examination. It was processed with personal computer after tests; we estimated breathing frequency with spectrum analysis of fluctuation of R wave amplitude. We examined reliability to be compared an estimated value with the reference value. In the results, although the estimated value was same as reference value for all subjects at 0.10 and 0.17Hz, a slight error was occurred in range from 0.01 to 0.02Hz at 0.25, 0.33 and 0.50Hz. In the second experiment, we examined the relation between tidal volume and the estimation error. In addition, we tested the effect of noise with activity of daily living. Eleven healthy subjects controlled their tidal volume at three grade: small, normal and large. Each of respiration patterns was continued for 2 minutes. They also walked on the treadmill at 4km/h for 2 minutes. We examined reliability to be compared the estimated value with the value of respiratory gas analyzer. In the results, the estimated value was almost same as reference value for normal and deep breathing. The relationship between tidal volume and the estimation error was not clear. During walking, the estimated breathing frequency was almost same as value of gas analyzer. In conclusion, it was proved that the estimation of breathing frequency with spectrum analysis of fluctuation of R wave amplitude had high reliability.

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The purpose of this study is to develop an automated method to detect mediastinal lymph nodes on chest CT scans for patients with lung cancer. First, the mediastinal region in which lymph nodes can exist was extracted. Second, detection of lymph node candidates by a CT-value thresholding technique and procedure of false-positive reduction by features were executed. Third, in order to utilize a priori knowledge of the lymph node position, the relationship between the slice location and anatomic section in human body was determined using an automatic classification of slice positions in terms of trachea and also using a genetic algorithm. Lastly, to remove the false-positive candidates, the knowledge information processing based on the anatomical information of the chest was executed. The sensitivity was 76%, and the correct detection rate was 72%. Our results show that the algorithm may be useful for the automated detection of lymph nodes.

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Several clinical examinations have so far been developed for patients with gustatory disturbances. However, most of them are based on the subjective reports by patients, not suitable to disclosing their psychogenic symptoms or fake diseases. Thus, the objective examinations have long been awaited. Whereas, the evoked EEG or MEG measurement has been established as objective methods for diagnoses of other sensory disturbances. To utilize them for diagnosis of gustatory disturbances, it is indispensable to develop a gustatory stimulator which can deliver gustatory pulses with a very short rise-time. It is critical also to make pure gustatory stimulation free from tactile contamination. Because such a stimulator has not been available, few experiments have addressed. In this study, we developed a gustatory apparatus to present the stimulus with a short rise-time (16.5ms). To evaluate the characteristics of this stimulator, we examined, in the following 3 MEG measurements, whether it presents pure gustatory sensation to the subjects without tactile contamination. Firstly, we compared the magnetic field (MF) changes in response to the presentation of the tastants (1M NaCl or 3mM saccharin) with those to the deionized water. We found remarkable MF responses to the tastants, but none to deionized water. The peak latency of saccharin is 114ms longer than that of NaCl. Secondly, we treated the subjects' tongue with gymnemate, a sweet-suppressing agent, before MEG measurement. Though 3mM saccharin evoked significant MF changes 380ms after the stimulus onset, the treatment abolished MF changes at this time-point. Finally, we investigated whether or not MF changes were dependent upon stimulus concentration: 1M NaCI evoked greater MF changes than 0.3M. The results indicate that the new gustatory stimulator delivers stimuli to evoke purely gustatory, but not tactile, sensation to subjects.

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Contamination of various artifacts into EEG (electroencephalogram) records often occurs in spite of technician's efforts to avoid them. In particular, blink artifacts contaminate in EEG records frequently, and often cause difficulties for interpreting and analyzing the recorded EEG. In this paper, a new method for eliminating blink artifacts in EEG records was developed. In general, individual blink artifacts have large variabilities for their amplitude and durations, therefore conventional averaging methods can not be adopted for estimating the waveform of blink artifacts directly. In order to acquire an accurate waveform of contaminated blink artifacts, waveform parameters for amplitude and duration of blink artifacts were measured from the EOG records. Normalization of respective blink artifacts was carried out by using the waveform parameters, then averaging of the normalized blink artifact was implemented. In addition to the normalization procedure, selective averaging by checking the waveform of each blink artifact was adopted. Finally, the respective blink artifacts were estimated by taking into account those properties and artifacts elimination was executed. Proposed method was applied to recorded EEGs and brought satisfactry performances in eliminating blink artifacts.

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We observed that an ST-T change of the ECG occurred just before ventricular premature contraction (VPC) in ambulatory ECG reproduced using a fast linear phase finite impulse response (FIR) filtering procession. We analyzed the characteristics of the waveform distortion induced by the FIR filtering and compared it with the contour effect, which is reported to induce a similar waveform distortion. Ambulatory ECG equipment used in the experiments were System 1 with the FIR filter and System 2 witout one. FIR filtering by System 1 caused pseudo ST-T abnormality immediately before VPC, while the System 1 without FIR filtering did not show a significant waveform change. The System 2 produced a substantial waveform distortion by the contour effect. In computer simulation, waveform distortions of square pulses depended on cut off frequency. To identify this phenomenon more clearly, we used a square pulse, which contains low frequency components as VPC does, as the test pulse. Large waveform distortions of the baselines before square pulses were observed both with the System 1 and the FIR filter and with the System 2. Computed simulation of the waveform distortion induced by the FIR filtering was also performed. The computed signal simulated the FIR filter-induced waveform change well. We conclude that the waveform distortion before VPC was produced by the FIR filtering procession, which we have been using to remove a baseline fluctuation of ambulatory ECG. This ECG wave distortion was similar to one induced by the contour effect. We should pay attention to this waveform distortion by the FIR filter in reading ambulatory ECG, in addition to the contour effect-induced distortion.

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In this paper, time-frequency properties of 1/f fluctuations of human heart rate variability (HRV) are analyzed. For this purpose, whole day recordings for 15 normal subjects are done by using a digital holter recorder under free moving conditions. A spectrogram of HRV is computed through sleep and wakefulness, which is reduced into powers in three frequency band LF (<0.05Hz), MF (0.05-0.15Hz), and HF (0.15-0.45Hz). Because these spectral powers are expected to represent hormonal and autonomic regulatory activities, distributions of balance among these spectral powers are obtained for sleep and wakefulness as an indicator of the regulatory activities on HRV. The balance distributions during wakefulness commonly show that MF and LF powers are dominant comparing with HF. During sleep, the balance distributions are extended from those similar to the wakefulness to region where HF power dominates LF and MF powers, which are shown to correspond to a rapid eye movement sleep (REM) and non-REM sleep, respectively. Analyses on overall transition tendency of the balance show distinct patterns for sleep and wakefulness: positive correlation between variations of LF power and HF/MF (balance between spectral powers in HF and MF) during wakefulness and negative during sleep. In addition, local transition tendency suggests that there are attractive points of balance which possibly correspond to the maintained physiological states such as sleep stages and postures. Through this study, the 1/f fluctuation of HRV is suggested to be constructed by the transition dynamics of the balance among the hormonal and autonomic regulatory activities which is wandering among the attractive points.

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Aiming at making a new gaze-drive interface, we examined if it is possible to detect where a gaze is between two different light sources by using the phenomenon that the farther a gaze is turned away from a stimulating light source, the more the VEP level decreases. The level of VEP was found to decrease exponentially as a function of angle of a gaze turned away from a light source. And when a subject gazed at a point between two light sources flickering in different frequency modes, the VEP contained two frequency components corresponding to the flickering modes, and the logarithmic ratio of the components was proportional to the position of a gaze between the two light sources. These results show the possibility to get a new gaze-drive interface. By using fewer light sources, this interface can realize as many menus as conventional ones which need light sources equal to menus in number.

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Paralyzed limbs of central-nervous-system impairment patients can be restored by electrically stimulated muscle contraction. This principle is called a functional electrical stimulation (FES). In their daily lives, the function of reaching to an object is one of the essential functions as shown in eating motion. We developed a system that enables a hand to move to desired positions by FES applied to the muscles of the arm. A subject puts on a cap, which mounted a red pointing light, and a position sensor on the wrist. The forearm is laid on an orthosis that can move only in horizontal plane. The pointing light gives the red beam whose diameter is approximately 15cm when it was illuminated from the height of 30cm on a plane. The subject projects the light beam from his head to a position sensor on his wrist. It detects the center of the illuminated area with differentially arranged phototransistors. A computer calculates stimulation patterns from the position data in order to guide the hand to the position, and a stimulator provides current pulses to the muscles of the upper limbs. The above procedure is repeated until the hand reaches to the target. While the light is not directed on the sensor, the position of hand is maintained at the current position. Experiments with a 22-year-old normal male subject were carried out to test the system. The light pointed to any targets from 30cm high, and his hand moved to the target position from the border of illuminated area. This system has the following advantages. 1) The hand can be moved from any initial position to any target position in horizontal plane. 2) The pointing light does not prevent subject's motion, and is easy to use.

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