"Development of system for diagnosis of early-stage arteriosclerosis using ultrasound"

在这项研究中，我们开发了一种测量局部脉冲波速度的新方法，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）由压力波从颈动脉传播到股动脉到达时间的差值获得。在这种方法中，可测量点仅限于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。因此，我们开发了一种基于超声多普勒效应的新系统，可以从皮肤表面无创地测量心壁或主动脉壁上的小振动信号。通过该系统，可以在高达1khz的频率范围内成功地检测到振幅为10 - 100 mm的振幅较大的心脏跳动引起的运动的小振动，持续超过10个节拍周期。本研究还开发了一种通过同时测量管壁和主动脉壁表面两点的微小振动来获得局部PWV的新方法。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。将所开发的系统和方法应用于体内实验，得到了在靠近主动脉瓣的主动脉壁上，振动波在主动脉壁上两点间传递的PWV。两点之间的距离大约是几毫米。还对每个测点的局部弹性（杨氏模量）进行了评估。因此，该系统可用于主动脉壁硬度的局部评估。少

In this research, we have developed a new method to measure local pulse wave velocity, 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 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.Therefore, we have developed a new system to noninvasively measure small vibration signals on the heart wall or the aortic wall from the surface of the skin based on the ultrasonic Doppler effect. … More By this system, small vibrations with amplitudes of 10 - 100 mum on the motion due to heart beat with the large amplitude of 10 mm are successfully detected in the frequency range up to 1 kHz continuously for more than ten beat periods from the chest.This research also developed a new method for obtaining local PWV by simultaneously measuring small vibrations at two points on the surface of the tube wall and 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.By applying the developed system and the method to in vivo experiments, the PWV of the vibration wave transmitted between the two points on the aortic wall is obtained even for the aortic wall near the aortic valve. The distance between the two points is about several millimeters. The local elasticity (Young's modulus) is also evaluated for each measurement point. Thus, the developed system will be effective for local evaluation of the hardness on the aortic wall. Less