Tomographic imaging of shear modulus elasticity of biological tissue based on ultrasonic measurement of internal displacement

触诊是检测软组织弹性变化的临床诊断手段，因为软组织的弹性通常与某些异常的病理过程有关。本研究的目的是基于超声测量的组织内部变形和位移来表征组织的弹性，当主要心脏搏动或外部机械力作用于软组织时。给出了各向同性、非均匀、不可压缩的生物软组织在外力作用下弹性参数的变分公式。给出整个组织的位移的知识。提出了一种基于有限元的静态变形模型，用于求解组织的相对剪切力或杨氏模量的分布。用简单三维夹杂问题的模拟变形数据验证了该方法的可行性。结果表明，…具有较高的通用性在各向同性、不可压缩的介质中，从感兴趣区域的局部测量的位移数据可以重建更多的相对剪切模数，并且仅从二维位移数据就可以恢复到一定程度的相对剪切模数。使用实时超声进行测量，并将从组织返回的RF回波信号序列数字化以估计局部组织位移。利用射频回波包络信号的时空导数估计内部位移的二维分布，由此计算内部应变张量的分量。实验结果表明，在5 mm×5 mm的空间分辨率下，可以估计出位移分量的二维场。重建了基于位移图像的相对剪切模量值分布。软组织的弹性可以用从接收到的射频回波信号中观察到的局部位移数据计算出的相对剪切模数来表征。较少

Palpation has been the clinical diagnostic modality to detect the changes in soft tissue elasticity, because the elasticity is usually related to some abnormal, pathological process. The goal of this study is to characterize tissue elasticity based on ultrasonic measurement of internal tissue deformation and displacement when the primary cardiac pulsation or the external mechanical force is applied to the soft tissue. A variational formulation is presented for the determination of the elasticity parameter of an isotropic, inhomogeneous, incompressible biological soft tissue, subject to external mechanical forces. Given a knowledge of the displacements throughout the tissue. A finite-element based model for static deformation is proposed for solving the distribution of the relative shear or Young's modulus of the tissue. The feasibility of the proposed method is demonstrated using the simulated deformation data of the simple three-dimensional inclusion problem. The results show that the … More relative shear modulus may be reconstructed from the displacement data measured locally in the region of interest within an isotropic, incompressible medium, and that the relative shear modulus can be recovered to some degree of accuracy from only 2-dimensional displacement data.Experiments on tissue mimicking phantoms were done. Mesurements are performed using real-time ultrasound and the sequences of RF echo signal returned from tissue ware digitized to estimate local tissue displacement. The 2-dimensional distribution of internal displacement was estimated using the spatio-temporal derivative of RF echo envelope signals, from which components of internal strain tensor were computed. Experimental results indicate that 2-dimensional fields of components of displacement can be estimated with the spatial resolution of 5mmx5mm. The distribution of the relative shear modulus based on displacement images was reconstructed. The elasticity of soft tissue can be characterized as the relative shear modulus computed from the local displacement data observed in the received RF echo signals. Less