Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA.
Department of Electrical and Computer Engineering, University of Rochester, Rochester, NY, USA
Ultrason Imaging. 2014 Oct;36(4):277-90. doi: 10.1177/0161734614527581. Epub 2014 Mar 21.
This article demonstrates the measurement of shear wave speed and shear speed dispersion of biomaterials using a chirp signal that launches waves over a range of frequencies. A biomaterial is vibrated by two vibration sources that generate shear waves inside the medium, which is scanned by an ultrasound imaging system. Doppler processing of the acquired signal produces an image of the square of vibration amplitude that shows repetitive constructive and destructive interference patterns called "crawling waves." With a chirp vibration signal, successive Doppler frames are generated from different source frequencies. Collected frames generate a distinctive pattern which is used to calculate the shear speed and shear speed dispersion. A special reciprocal chirp is designed such that the equi-phase lines of a motion slice image are straight lines. Detailed analysis is provided to generate a closed-form solution for calculating the shear wave speed and the dispersion. Also several phantoms and an ex vivo human liver sample are scanned and the estimation results are presented.
本文展示了使用啁啾信号测量生物材料的剪切波速度和剪切波频散的方法,该啁啾信号可以在一系列频率上发射波。两个振动源使生物材料振动,在介质内部产生剪切波,这些剪切波由超声成像系统进行扫描。对采集到的信号进行多普勒处理,产生振动幅度平方的图像,显示出称为“爬行波”的重复建设性和破坏性干扰模式。使用啁啾振动信号,可以从不同的源频率生成连续的多普勒帧。收集的帧生成独特的模式,用于计算剪切波速度和剪切波频散。设计了一种特殊的互易啁啾,使得运动切片图像的等相线条是直线。提供了详细的分析,以生成用于计算剪切波速度和频散的闭式解。还扫描了几个幻影和一个离体人肝样本,并给出了估计结果。