Dore Marta, Luna Aime, Royston Thomas J
Richard and Loan Hill Department of Biomedical Engineering, University of Illinois Chicago, 851 South Morgan Street, MC 063, Chicago, IL 60607.
J Eng Sci Med Diagn Ther. 2023 Feb 1;6(1):011006. doi: 10.1115/1.4056103. Epub 2022 Nov 23.
Dynamic elastography attempts to reconstruct quantitative maps of the viscoelastic properties of biological tissue, properties altered by disease and injury, by noninvasively measuring mechanical wave motion in the tissue. Most reconstruction strategies that have been developed neglect boundary conditions, including quasi-static tensile or compressive loading resulting in a nonzero prestress. Significant prestress is inherent to the functional role of some biological tissues, such as skeletal and cardiac muscle, arterial walls, and the cornea. In the present article a novel configuration, inspired by corneal elastography but generalizable to other applications, is studied. A polymer phantom layer is statically elongated via an in-plane biaxial normal stress while the phantom's response to transverse vibratory excitation is measured. We examine the interplay between biaxial prestress and waveguide effects in this plate-like tissue phantom. Finite static deformations caused by prestressing coupled with waveguide effects lead to results that are predicted by a novel coordinate transformation approach previously used to simplify reconstruction of anisotropic properties. Here, the approach estimates material viscoelastic properties independent of the nonzero prestress conditions without requiring advanced knowledge of those stress conditions.
动态弹性成像试图通过非侵入性测量组织中的机械波运动，重建生物组织粘弹性特性的定量图谱，这些特性会因疾病和损伤而改变。大多数已开发的重建策略都忽略了边界条件，包括导致非零预应力的准静态拉伸或压缩载荷。显著的预应力是一些生物组织功能作用所固有的，如骨骼肌、心肌、动脉壁和角膜。在本文中，研究了一种受角膜弹性成像启发但可推广到其他应用的新型配置。通过面内双轴法向应力使聚合物仿体层静态伸长，同时测量仿体对横向振动激励的响应。我们研究了这种板状组织仿体中双轴预应力与波导效应之间的相互作用。预应力引起的有限静态变形与波导效应相结合，导致了由一种先前用于简化各向异性特性重建的新型坐标变换方法所预测的结果。在此，该方法无需预先了解这些应力条件，就能独立于非零预应力条件估计材料的粘弹性特性。
