超声弹性成像仿真研究

发布时间：2018-05-15 13:40

本文选题：弹性成像 + 软组织　；参考：《南京大学》2014年硕士论文

【摘要】：本文研究了利用超声对生物软组织进行弹性成像的问题。普通的超声成像以声阻抗作为成像参数,仅可以反映出组织的声学性质变化与分布。当病变处的声阻抗变化很小、弹性变化很大时,需要利用超声弹性成像来检测组织的力学性质变化。自弹性成像的概念提出以来已有二十余年。为了实现对软组织的弹性性质进行实时、快速、高分辨率地成像,理论与临床实验研究不断发展,弹性成像也逐渐成为超声成像医学应用领域的研究热点之一。超声弹性成像的实现原理主要包括传统弹性成像,辐射力成像和剪切波成像。传统弹性成像是一种基于弹性力学的静态压缩方法,通过应变估计可以得到组织全局的弹性分布。前人的研究主要包括原理验证、算法改进、信号处理、噪声抑制以及逆问题研究等方面。辐射力成像和剪切波成像是基于声辐射力的新型成像方法,能够获得声聚焦附近的局部弹性信息,移动聚焦位置可以得到弹性性质的全局分布情况。本文对超声弹性成像的原理与发展做了综述,并利用有限元法对生物软组织的超声弹性成像进行仿真研究。通过改变组织内部杨氏模量分布及数值大小,仿真计算出各种不同情形时的位移和应变分布,并对仿真结果进行分析。在考虑生物组织粘弹性的基础上,优化了组织模型,仿真更接近真实情况。仿真结果表明,利用微小应变压缩法可以实现对离体组织的弹性分布成像,考虑粘弹性的仿真结果显示组织内部的应力、应变及位移变化均为时间的函数。
[Abstract]:The elastic imaging of biological soft tissue by ultrasound is studied in this paper. The acoustic impedance is used as the imaging parameter in the ordinary ultrasonic imaging, which can only reflect the change and distribution of the acoustic properties of the tissue. When the acoustic impedance of the lesion is very small and the elastic change is very large, it is necessary to detect the change of the mechanical properties of the tissue by using the ultrasonic elastic imaging. It has been more than 20 years since the concept of elastic imaging was put forward. In order to realize real-time, rapid and high-resolution imaging of soft tissue elastic properties, theoretical and clinical experimental studies have been developed continuously, and elastic imaging has gradually become one of the research hotspots in the field of ultrasonic imaging medical applications. The principle of ultrasonic elastic imaging includes traditional elastic imaging, radiation imaging and shear wave imaging. Traditional elastic imaging is a static compression method based on elastic mechanics, and the global elastic distribution can be obtained by strain estimation. Previous studies include principle verification, algorithm improvement, signal processing, noise suppression and inverse problems. Radiation force imaging and shear wave imaging are new imaging methods based on acoustic radiation force, which can obtain the local elastic information near the acoustic focusing, and the global distribution of elastic properties can be obtained by moving the focusing position. In this paper, the principle and development of ultrasonic elastic imaging are reviewed, and the ultrasonic elastic imaging of biological soft tissue is simulated by finite element method. By changing the Young's modulus distribution and its numerical value, the displacement and strain distributions in various cases are calculated and the simulation results are analyzed. On the basis of considering the viscoelasticity of biological tissue, the tissue model is optimized, and the simulation is closer to the real situation. The simulation results show that the micro-strain compression method can be used to image the elastic distribution of isolated tissue. The simulation results with viscoelasticity show that the variation of stress strain and displacement in the tissue is a function of time.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R445.1

【共引文献】