Digital image processing techniques are applied to the extraction of three-dimensional (3-D) information on coronary arteries from mutually orthogonal cineangiograms (e. g. RAO 30 degrees and LAO 60 degrees). Both cineangiograms are of the same scale factor and carefully registered in space. The registration in time is done by determining the end-diastole phase and the end-systole phase on the cineangiograms. The registration of left and right coronary arteries (LCA and RCA) is done by detecting a small intentional leak of contrast material so as to show both entrances of LCA and RCA.
Corresponding points in RAO and LAO images are conversationally selected on a display and their 3-D coordinates are calculated. 3-D structure of coronary arteries are approximated by lines which connect points thus obtained. Its view from any direction can be displayed. Branches are color coded to make the identification easy. A 16mm film and a video tape are used to show the rotation of 3-D structure around an arbitrary axis. Stereoscopic pairs of arteries are also presented. These display techniques are quite effective in understanding the 3-D structure of coronary arteries.
The 3-D spatial shape surrounded by coronary arteries is obtained as the stacking of cross sections. This shape can be considered to reflect the outer shape of the heart. Each cross section is approximated by the third order spline curve which connects the cross points between arteries and the cross plane.

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The purpose of this study is to develop a method of estimating transition probabilities between the disease “states” indicating its severity for the chronic diseases, in which repeated observations to estimate the probabilities are difficult. This method has been applied to the analysis of the natural history of patients with coronary heart diseases. The transition process among “states” is assumed to be expressed by a time discrete simple Markov process. Nine years' follow-up data on coronary heart diseases by Bruschke et al. have been used for the present analysis. The severity of the disease is classified into 3 “states”, i. e., S₁: single vessel disease, S₂: double vessel disease, and S₃: triple vessel disease. Estimation of the parameters (transition probabilities) was made by the maximum likelihood method, using the follow-up data on the numbers of the survival. The accuracies of the estimated values are evaluated by the asymptotic variances. An information criterion AIC is used to compare the aptness of applicability among several supposed Markov models. From the present study the following have been obtained: (1) the accuracy of the curve fitting for the follow-up data was satisfactory, (2) the catenary model was most prominent in the sense that the AIC is minimum, and (3) there may exist reversible transitions among some disease states.

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Geometric illusions closely relate to the excellent functions of the human visual system. The authors formerly analyzed several typical illusions by a lateral inhibition model assuming that the geometric illusions originated from interactions of neuronal activities in the visual system.
In this paper, we have proposed a new model to interpret illusions on the basis of the assumption that the illusions were caused by multiple spatial frequency channels, the existence of which has been proposed in both physiological and psychological visual science. Taking ‘Helmholtz-Hering illusion’ as an example, we analyzed the kinds of channel that produced illusions.
It is shown that the new model is effective to interpret the Helmholtz-Hering illusion, and that this illusion originates mainly from the channels having 1-octave bandwidth and the central frequency of about half of the fundamental frequency of the illusional figure. It will be possible to analyze more complex illusions by this model in near future.

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A computerized analysis system for the masticatory muscles has been developed. Silent period (SP), which observed in masticatory muscles shortly after the tooth contact during tapping movements or after chin tap during clenching, has been determined of its diagnostic value for TMJ dysfunction.
This system has the following characteristics; 1) applicable for a dental clinic, 2) automated objective measurements of the SP parameters, and 3) easy data processing for statistical analyses.
In order to measure the SP parameters, threshold level technique and peak to peak technique are common. However, since these techniques have some disadvantages, a new technique, “activity changing curve” has been developed. This parameter is independent of the amplitude of the EMG and shows marked increase at the onset or the termination of the SP. Thus it indicates the SP parameters more clearly and more objectively than the other methods.
We are proposing a four muscles and four divisions coordination pattern analysis, which shows a status of the masticatory function by means of durations and integrated values of the masticatory muscles and a stochastic analysis, which shows constitution of the SP by means and standard deviations of the EMG signal at each time.
As the results of this systematic analyses for clinical examination of many subjects, the patients with TMJ dysfunction showed significantly variation of SP duration etc. This clinical application has proved the efficiency of this system.

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A new automated method measuring the antibiotic susceptibility and the minimal inhibitory concentration (MIC) for bacteria contaminated by drug-resistant types is proposed. The growth curves of 10 drug channels and one reference channel are monitored continuously by the turbidity of the culture broth. From the analysis of the bacterial growth curves, new growth rate parameters D and G are obtained. With these parameters, MIC are calculated and displayed automatically on the monitor TV every one hour after inoculation. The profile of G and D against the concentration of drug and the time course of MIC can give information of the existence of drug-resistant bacteria. The MIC obtained by long time measuring is evaluated from the time course of MIC.

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The information structure of body surface potential distributions has been analyzed according to the concepts of Karhunen-Loève transform and of information entropy. As a result of the Karhunen-Loève transform, 10 components were extracted as the effective information patterns and their accumulated contribution rate was found to be 96.0%. The first three components resembled dipolar patterns and the other seven components showed complicated patterns. From entropy analysis, the simple information amount at each lead reached the maximum at 3.41 bits on the left precordial field. The specific information amount at each lead, free from the effect of correlation with the rest of leads, showed positive values only in the limited region of the left precordial field. The information amounts of all the leads totaled 10.33 bits. Based on the results of the information amount distributions, we proposed a 30-electrode system which reduces the redundancy of the 96-electrode system. The 30-electrode system could explain 97% of the 96-channel body surface potentials.

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Ruby laser is effective in treating pigmented skin tumors, such as melanomas and nevus. The conventional ruby laser unit, however, is limited in practical use due to its uneven beam distribution over the target area. To overcome this problem we have developed a new ruby laser system utilizing a kaleidoscope as an application head.
The spatial ununiformity of the kaleidoscope output as well as its efficiency varies depending on the kaleidoscope length, reflection ratio, the incident beam spread angle, incident position, etc. Therefore, the kaleidoscope has excellent characteristics for our purposes, when these items are set to proper values. Up to the present, however, there has been no theory to define the relationship between these factors. So, we have conducted research to establish such a theory. Basic data, which are indispensable in seeking an optimum design, have been collected by simulation.
During the research, we employed the total reflection method utilizing a dielectric substance to conduct simulations, and constructed a trial model based on these results. Its output energy is 20-40J/cm² over a 10²mm irradiated area. The pulse interval is 1 msec. The spatial ununiformity of the output intensity on the kaleidoscope output surface was found to be below 12%, which is close to the simulated data.
After confirming the safety and clinical applicability of this system, we applied it to treating 20 patients suffering from nevus spilus. Irradiated by a 40J/cm² (1 msec) ruby laser, 18 out of the 20 cases showed favorable results, though the other two cases suffered recurrence.
The following problems remain to be solved in the future: to improve the efficiency of the kaleidoscope by applying a non-reflective coating to its input and output terminal surfaces; to develop an optical fiber for use with the laser beam to facilitate the system's operation. Clinical application of the system to study recurring cases is the future task.

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A real-time continuous monitoring system of the ST-segment of electrocardiogram has been developed at our laboratory. This system calculates a spatial ST magnitude and two angles (azimuth and elevation) from three-channel Frank electrocardiograms following the formula with a micro-computer. Spatial ST magnitude=√ST_X²+ST_Y²+ST_Z², Azimuth=tan^-1ST_Z/ST_X, Elevation=tan^-1 ST_Y/√ST_X²+ST_Z². These data are displayed on a CRT displaying system (4 channels) and a penwriting recorder (6 channels) simultaneously. This system could record changes of spatial ST magnitude on experimental coronary artery occlusion. It is concluded that this system will be useful as a non-invasive monitoring of myocardial ischemia or injury in intensive care units.

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