Quantitative Assessment of Tissue Hardness of Coronary Artery Wall Specimens by Acoustic Tissue Characterization System with a Wide Band Frequency Ultrasound.

本研究的目的是开发一种能够定量测量生物标本中的组织特征的声学组织定征系统，并使用该系统来评估组织硬度，特别是人体冠状动脉壁的硬度。我们主要在450 MHz的扫描声学显微镜(HSAM-500S)上开发了用于组织特性的定量测量系统。为了精确测量超声波的绝对传播速度，我们制作了一个新的试件安装平台，可以精确地调节试件厚度和客观试件环境的温度。我们能够通过读取干涉条纹漂移的图案来判断样品厚度的准确性，并确保样品周围环境的温度可以控制在*0.1ﾟC.2的精度。我们使用用于控制温度…的数字电压表来检测超声波传播速度随温度的变化更自信。4微米厚的肝脏、心肌和冠状动脉标本被安装在恰好4微米深的工作台上，之后我们测量了在不同控制温度下的传播速度。在30ﾟC和50ﾟC之间，3种组织的传播速度随温度的增加速率依次为：肝脏；2.68m/S/ﾟC，心肌；4.26m/S/ﾟC，冠状动脉(内膜)；0.60m/S/ﾟC，证实了3种组织的传播速度随温度的不同而不同，因此每个组织都具有温度相关的声学特性。我们测量了13例各种疾病的尸检标本中超声在冠状动脉内膜中的绝对传播速度。根据光学显微镜下内膜的发现，我们将这些标本分为3组：正常、早期硬化和晚期硬化。25ﾟC超声传播速度：正常1947.3×100.2m/S，早期1694.3×64.1m/S，晚期2246.3×96.0m/S，一般传播速度越快组织越硬。因此，我们得出结论，与正常组织相比，疾病早期光学定义的硬化性内膜组织显示出最初的软化，随后是随着钙化的推进而硬化。随着10-100 MHz超声对生物样品中组织特性的定量评估，我们正在进行一种新系统的开发和测量组织中超声波吸收衰减的实验研究，例如。血液或冠状动脉，使用50 MHz超声系统。较少

The aim of this study was to develop an acoustic tissue characterization system able to quantitatively measure tissue characteristics in biological specimens, and to evaluate tissue hardness, especially of the human coronary artery wall, using this system.1. We developed the quantitative measurement system for tissue characterization mainly from a scanning acoustic microscope(HSAM-500S) operating at 450MHz. To precisely measure the absolute propagation velocity of ultrasound, we made a new stage for mounting specimens to precisely regulate both specimen thickness and temperature of the objective specimen environment. We were able to judge the accuracy of the specimen thickness by reading patterns of the interference fringe shift, and also ensure that the temperature of the environment around the specimen could be controlled with an accuracy of *0.1ﾟC.2. We examined temperature-dependent changes in the propagation velocity of ultrasound using a digital voltmeter for controlling temperat … More ure. 4-micron-thick specimens of liver, myocardium and coronary artery were mounted on a stage of exactly 4 microns depth, after which we measured propagation velocities at various controlled temperatures. The rates of increase in propagation velocity with temperature in the 3 tissues between 30ﾟC and 50ﾟC were as follows : liver ; 2.68m/s/ﾟC, myocardium; 4.26m/s/ﾟC, coronary artery (intima) ; 0.60m/s/ﾟC. We confirmed that propagation velocity varied distinctly in each of the 3 tissues according to the temperature of the specimen, and that therefore each tissue had temperature-dependent acoustic characteristics.3. We measured the absolute propagation velocity of ultrasound in the intima of human coronary artery specimens obtained by autopsy from 13 patients with a variety of diseases. On the bases of findings in the intima with an optical microscope, we classified these specimens into 3 groups; normal, early stages of scleroses, and advanced stages of sclerosis. Ultrasound propagation velocity at 25ﾟC was as follows : normal; 1947.3*100.2m/s, early stage; 1694.3*64.1m/s, advanced stage; 2246.3*96.0m/s. Generally, the faster the propagation velocity, the harder the tissue. We therefore concluded that optically defined sclerotic intima tissue in early stages of disease showed an initial softening as compared with normal tissue, and this was followed by subsequent hardening with advancing calcification.4. As quantitative assessment of tissue characteristics in biological specimen by 10-100MHz ultrasound, we were getting on with the development of a new system and the experimental study to measure the attenuation due to absorption of ultrasound through the tissue, ex. blood or coronary artery, using 50MHz ultrasound system. Less