Clarification of relation between acoustic characteristic and ultrasonic image of biological tissue

在使用超声诊断仪进行临床诊断时，仅利用超声B超图像的二维平面信息很难了解组织结构。为了了解肝纤维化等疾病引起的组织改变与超声图像回波信号特征变化之间的关系，设计了三维回波滤光片，以提高超声诊断设备采集数据的准确性。辐照人体的超声束的分辨率在深度、方位和仰角方向上各不相同。在此基础上，根据三维方向分辨率确定滤波器参数，提高了各分量的测量精度，并提出了定量诊断的信号分析方法。该方法考虑了人体回波信号的散射密度与回波信号特征之间的关系。将多种分析方法相结合，可以对非均匀介质(病变组织)中不同成分的声学特性进行量化，并对生物组织声学特性的高速、高密度测量系统进行了改造。通过对8个肝脏标本的测量，测量速度和可测量范围比以前的系统提高了四倍。结果，由于测量环境的改变而引起的误差减小，并且高精度测量成为可能。

In the clinical diagnosis using ultrasonic diagnostic equipment, it is difficult to understand the tissue structure by using only two dimensional plane information of ultrasonic B-mode image. In this research, we tried to understanding the relationship between the tissue change that caused by some disease such as fibrosis and the characteristics change (of echo signal for ultrasonic images).The three dimensional echo filter was disigned to improve the accuracy when data is collected with ultrasonic diagnostic equipment. The resolution of the ultrasonic beam which was irradiated to human body is differs respectively in depth, the azimuth, and the direction of the elevation. Then, the measurement accuracy for every has been improved by deciding the parameter of the filter based on resolution in the direction of three dimensions.Moreover, we proposed signal analyzing methods for quantitative diagnosis. Our methods paid attention to the relation between the scatter density and the characteristics of echo signal in the living human body. Quantifying the feature of a different element in an inhomogeneous medium (diseased tissue) became possible by combining some analytical methods.In addition, the system to measure the acoustic characteristic of the biological tissue high-speed and in a high density was restructured. As a result of measurement of eight liver specimens, the measurement speed and the range that can be measured quadrupled compared with the previous system. As a result, the error margin because of the change in the measurement environment decreased, and a highly accurate measurement became possible.