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For t h e noninvasive diagnosis of heart disease based on t h e acoustic characteristics of t h e h e a r t muscle, we have developed a new m e t h o d for accurately tracking t h e movement of t h e heart wall. By this method, a velocity signal of t h e h e a r t wall with a small amplitude of less t h a n 10 p m on t h e motion resulting from a h e a r t b e a t with large amplitude of 10 m m can be successfully detected with sufficient reproducibility in t h e frequency range up t o several hundred H e r t z continuously for periods of a b o u t 10 heartbeats. In this paper, t h e m e t h o d is applied t o multiple points preset in t h e left ventricular (LV) wall along t h e ultrasonic b e a m so t h a t t h e spatial ( d e p t h ) distributions of t h e velocity at these points are simultaneously obtained.T h e motion of t h e heart wall is divided into t h e following two components: parallel global motion of t h e heart wall a n d the change in myocardial layer thickening at each d e p t h across t h e LV wall during myocardial contraction/relaxation.T h e latter component is superimposed on t h e M (motion)mode image using a color code t o m a p contraction as red and expansion as blue. By preliminary human studies, t h e principle of t h e m e t h o d proposed in this paper is verified a n d t h e frequency band of t h e components generated by thickening a n d / o r thinning in t h e myocardium is identified. This new approach offers potential for research on noninvasive acoustical diagnosis of myocardial local motility, t h a t is, t h e myocardial layer function at each d e p t h in t h e ventricular wall.

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A new method for non-invasively evaluating the Poisson ratio of an arterial wall using ultrasound is presented.

For the diagnosis of the early stages of atherosclerosis, it is important to evaluate the local acoustic characteristics of the arterial wall. For this purpose, it is necessary to increase the spatial resolution in the axial direction to several millimeters, which corresponds to the size of the macular lesion on the surface of the wall. We have proposed a method for measuring small velocity signals on the intima and adventitia of the arterial wall from the skin surface using pulsive ultrasonic waves. The small change in thickness of the arterial wall is obtained by integrating the difference between the two velocity signals on the intima and adventitia. The elastic property of the arterial wall is noninvasively evaluated from the change in thickness and the arterial inner pressure. In this paper, we evaluate the accuracy of the proposed method for measuring the small displacement. Moreover, we applied this method to evaluate the elastic property of the arterial wall of 50 patients and 8 healthy subjects.

In order to diagnose ventricular dysfunction based on the acoustic characteristics of the heart muscle of the ventricle, it is necessary to detect vibration signals from various parts of the ventricular wall. This is, however, difficult using previously proposed ultrasonic diagnostic methods or systems. The reason is that the amplitude of the cardiac motion is large during one beat period which produces large fluctuations in the transit time required for ultrasonic waves to travel from the transducer to the heart and back. This paper proposes a new method for overcoming this problem and accurately measuring small vibrations of the ventricle wall using ultrasound. In this method, the demodulated ultrasound signal reflected at the heart wall is converted from analogue to digital (A/D) signal at a high sampling frequency; from the resultant digital signal, the velocity of the wall is accurately obtained over a wide dynamic range based on the Doppler effect. The proposed method is preliminarily applied to the detection of small vibrations on the aortic wall and the interventricular septum. The new method offers potential for research in acoustical diagnosis of heart and artery dysfunction.