Saijo Y, Sasaki H, Naganuma T, Tanaka M
Department of Medical Engineering and Cardiology, Tohoku University, Sendai.
J Cardiol. 1995 Mar;25(3):127-32.
Ultrasonic tissue characterization of the myocardium has become very important because the requirement for evaluating local cardiac function has increased. In the present study, the acoustic properties of the tissue elements in myocardial infarction were measured by a specially developed scanning acoustic microscope (SAM) system, and the echo intensity of the infarcted myocardium was assessed. Ten samples of infarcted myocardium obtained at autopsy were formalin-fixed, paraffin-embedded and cut into 10 microns thick slices. The SAM system was operated in the frequency range of 100 to 200 MHz. The values of the attenuation constant and sound speed were measured in five tissue elements, normal myocardium, degenerated myocardium, fibrosis, granulation, and hemorrhage by comparing the optical microscopic image and acoustic images. The density of each tissue element was measured by the CuSO4 method, and the specific acoustic impedance was calculated by multiplying the sound speed and the density of each tissue element. The specific acoustic impedance was 1.75 x 10(6) Ns/m3 in normal myocardium, 1.69 x 10(6) Ns/m3 in degenerated myocardium, and 1.85 x 10(6) Ns/m3 in fibrosis. The intensity of the reflected ultrasound at the interface between two different tissue elements was calculated by the difference of specific acoustic impedance. Using the sensitivity changing method in clinical echocardiography, the intensity of myocardial scar was -15 dB compared to the pericardial echo. The corrected ideal ultrasonic reflection between degenerated myocardium and fibrosis was calculated as -15.4 dB. The results suggest that measurement of acoustic properties is very important to provide basic data for ultrasonic characterization of myocardium tissue.
由于评估局部心脏功能的需求增加，心肌的超声组织特征分析变得非常重要。在本研究中，通过专门开发的扫描声学显微镜（SAM）系统测量了心肌梗死中组织成分的声学特性，并评估了梗死心肌的回声强度。从尸检中获取的10份梗死心肌样本用福尔马林固定、石蜡包埋，然后切成10微米厚的切片。SAM系统在100至200MHz的频率范围内运行。通过比较光学显微镜图像和声图像，在正常心肌、变性心肌、纤维化、肉芽组织和出血这五种组织成分中测量了衰减常数和声速的值。通过硫酸铜法测量每个组织成分的密度，并通过将声速与每个组织成分的密度相乘来计算比声阻抗。正常心肌的比声阻抗为1.75×10(6)Ns/m3，变性心肌为1.69×10(6)Ns/m3，纤维化组织为1.85×10(6)Ns/m3。通过比声阻抗的差异计算两种不同组织成分之间界面处反射超声的强度。使用临床超声心动图中的灵敏度变化方法，与心包回声相比，心肌瘢痕的强度为-15dB。变性心肌与纤维化之间的校正理想超声反射计算为-15.4dB。结果表明，声学特性的测量对于为心肌组织的超声特征分析提供基础数据非常重要。
