He Qiong, Li Guo-Yang, Lee Fu-Feng, Zhang Qihao, Cao Yanping, Luo Jianwen
Department of Biomedical Engineering, School of Medicine, Tsinghua University, Beijing, China; Center for Biomedical Imaging Research, Tsinghua University, Beijing, China.
Institute of Biomechanics and Medical Engineering, AML, Department of Engineering Mechanics, Tsinghua University, Beijing, China.
Ultrasound Med Biol. 2017 Jul;43(7):1520-1532. doi: 10.1016/j.ultrasmedbio.2017.03.001. Epub 2017 Apr 10.
Many studies have investigated the applications of shear wave imaging (SWI) to vascular elastography, mainly on the longitudinal section of vessels. It is important to investigate SWI in the arterial cross section when evaluating anisotropy of the vessel wall or complete plaque composition. Here, we proposed a novel method based on the coordinate transformation and directional filter in the polar coordinate system to achieve vessel cross-sectional shear wave imaging. In particular, ultrasound radiofrequency data were transformed from the Cartesian to the polar coordinate system; the radial displacements were then estimated directly. Directional filtering was performed along the circumferential direction to filter out the reflected waves. The feasibility of the proposed vessel cross-sectional shear wave imaging method was investigated through phantom experiments and ex vivo and in vivo studies. Our results indicated that the dispersion relation of the shear wave (i.e., the guided circumferential wave) within the vessel can be measured via the present method, and the elastic modulus of the vessel can be determined.
许多研究已经探讨了剪切波成像（SWI）在血管弹性成像中的应用，主要集中在血管的纵向切片上。在评估血管壁的各向异性或完整斑块成分时，对动脉横截面进行SWI研究很重要。在此，我们提出了一种基于极坐标系中的坐标变换和方向滤波器的新方法，以实现血管横截面剪切波成像。具体而言，超声射频数据从笛卡尔坐标系转换到极坐标系；然后直接估计径向位移。沿圆周方向进行方向滤波以滤除反射波。通过体模实验、离体和在体研究，探讨了所提出的血管横截面剪切波成像方法的可行性。我们的结果表明，通过本方法可以测量血管内剪切波（即引导圆周波）的频散关系，并确定血管的弹性模量。
