"Development of system for measurement and analysis of small vibration on heart wall for early stage diagnosis of myocardium"

在这项研究中，我们开发了一种新的系统来精确测量心壁上的微小振动信号。通过这种方法，可以成功地检测到由10 mm的大幅度心跳引起的小幅度小于100微米的心壁小振动，并且在高达几百赫兹的频率范围内连续10次心跳的周期具有足够的重复性。所产生的微小振动不仅在时间域中分析，而且在频率域中分析。实验证明，该方法为心脏疾病的声学诊断提供了可能。在本研究中，将该方法应用于沿超声波束在左室壁内预置的多个点，从而同时获得这些点上的速度的空间(深度)分布。心壁的运动可分为两个部分：心壁的平行整体运动和心肌收缩/松弛过程中跨室壁各深度心肌层增厚的变化。使用颜色编码将后一分量叠加在M(运动)模式图像上，以将收缩映射为红色，将扩展映射为蓝色。通过初步的人体实验，验证了本文提出的方法的原理，并识别了心肌增厚和/或变薄所产生的成分的频带。这一新方法为心肌局部运动的无创性声学诊断研究提供了可能，即室壁各深度的心肌层功能。

In this research, we have developed a new system to accurately measure small vibration signal on the heart wall. By this method, small vibrations of the heart wall with small amplitudes less than 100 mum on the motion resulting from a heartbeat with large amplitude of 10 mm can be successfully detected with sufficient reproducibility in the frequency range up to several hundred Hertz continuously for periods of about ten heartbeats. The resultant small vibration is analyzed not only in the time domain but also in the frequency domain. As confirmed by the experiments herein reported, the new method offers potential for research in acoustical diagnosis of heart disease.In this research, the method is applied to multiple points preset in the left ventricular (LV) wall along the ultrasonic beam so that the spatial (depth) distributions of the velocity at these points are simultaneously obtained. The motion of the heart wall is divided into the following two components : parallel global motion of the heart wall and the change in myocardial layr thickening at each depth across the LV wall during myocardial contraction/relaxation. The latter component is superimposed on the M (motion) -mode image using a color code to map contraction as red and expansion as blue. By preliminary human studies, the principle of the method proposed in this paper is verified and the frequency band of the components generated by thickening and/or thinning in the myocardium is identified. This new approach offers potential for research on noninvasive acoustical diagnosis of myocardial local motility, that is, the myocardial layr function at each depth in the ventricular wall.