A Study on development of realtime system for diagnosis of regional elasticity of myocardium and arterial wall using ultrasound

在这项研究中，我们开发了一种新的系统，可以精确测量心脏壁和动脉壁上的微小振动信号。通过这种方法，可以成功地检测到由振幅为10毫米的大心跳引起的小于100毫米的心壁小振动，并且在高达几百赫兹的频率范围内具有足够的再现性，连续周期约为10次心跳。对振动产生的小振动不仅进行了时域分析，而且进行了频域分析。初步实验结果表明，该方法在心脏疾病的声学诊断研究中具有广阔的应用前景。另一方面，该系统也适用于局部脉冲波速度的测量，这是主动脉壁硬度在几毫米范围内的指标。在标准方法中，脉冲波速（PWV）由从颈动脉传播到股动脉的压力波到达时间的差值获得。在这种方法中，可测量的点仅限于那些主动脉存在于皮肤表面附近的点，这些点之间的距离相当长，即几百毫米。然而，测量动脉壁表面的局部硬度对早期诊断很重要。为了提高空间分辨率，有必要测量频率成分高达50 Hz左右的脉冲波引起的振动。所开发的系统还可以通过同时测量主动脉壁表面两点的微小振动来测量局部PWV。该方法可获得较高的空间分辨率，这是评价局部硬度所必需的。通过对比硅管的静态实验和动态实验，证实了该方法对管壁的局部硬度（杨氏模量）也具有较高的空间分辨率。还对每个测点的局部弹性（杨氏模量）进行了评估。因此，所开发的系统也将有效地局部评估主动脉壁的硬度。少

In this research, we have developed a new system to accurately measure small vibration signal on the heart wall and arterial 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 preliminary experiments herein reported, the new method offers potential for research in acoustical diagnosis of heart disease.On the other hand, this system is also applicable to the measurement of local pulse wave velosity, which is an index of the hardness in the range of several millimeters on the aortic wall. In the standard method, the pulse wave velocity (PWV) is obtained from the difference in arrival time of … More pressure waves propagating from the carotid artery to the femoral artery. In this method, the measurable points are limited to those where the aorta exists near the skin surface and the distance between such points is considerable long, i. e., several hundred millimeters. It is important for early diagnosis, however, to measure the local hardness of the surface of the arterial wall. To increase the spatial resolution, it is necessary to measure vibrations due to pulse waves with frequency components up to about 50 Hz.The developed system is also applied to measurement of local PWV by simultaneously measuring small vibrations at two points on the surface of the aortic wall. By the developed method, high spatial resolution, which is necessary in the evaluation of local hardness, is attained. By comparing the static experiments and dynamic experiments using a silicon tube, it is confirmed that the local hardness (Young's modulus) of the vessel wall is also evaluated with high spatial resolution. The local elasticity (Young's modulus) is also evaluated for each measurement point. Thus, the developed system will be effective also for local evaluation of the hardness on the aortic wall. Less