Coupling between elastic strain and interstitial fluid flow: ramifications for poroelastic imaging
Coupling between elastic strain and interstitial fluid flow: ramifications for poroelastic imaging
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DOI：
10.1088/0031-9155/51/24/002
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发表时间：
2006-12-21
影响因子：
3.5
通讯作者：
Bamber, Jeffrey C.
中科院分区：
文献类型：
--
作者：
Leiderman, Ricardo;Barbone, Paul E.;Bamber, Jeffrey C.
我们研究了组织间液流动和组织间液引流对软组织应变时空响应的影响。动机源于通过弹性成像测量软组织中的体内应变分布的能力，以及探索使用这种技术来研究软组织流体流动的可能性的愿望。我们的研究是基于文献中软组织力学的数学模型。它是双相理论的简单概括，包括软组织的流体和固体相之间的耦合，以及至关重要的是，微血管和局部微血管之间的流体交换。我们用有限元法（FEM）求解二维数学方程。有限元实现验证对一个精确的解析解，推导出附录。从文献中的现实输入组织属性与有限元建模结合使用，进行几个计算实验。这些结果导致以下结论：（i）不同的假设流动机制导致应变松弛随时间的不同模式;（ii）代表性的组织性质显示流体引流到局部微脉管系统中是主要的流动相关应力/应变松弛机制;（iii）由于引流到微脉管系统中，实体肿瘤中应变的松弛时间为5-10 s的量级;（iv）在实际施加的压力大小下，应变松弛的大小可以高达约0.4%应变（4000微应变），这完全在弹性成像可测量的应变范围内。
We study the effects of interstitial fluid flow and interstitial fluid drainage on the spatio-temporal response of soft tissue strain. The motivation stems from the ability to measure in vivo strain distributions in soft tissue via elastography, and the desire to explore the possibility of using such techniques to investigate soft tissue fluid flow. Our study is based upon a mathematical model for soft tissue mechanics from the literature. It is a simple generalization of biphasic theory that includes coupling between the fluid and solid phases of the soft tissue, and crucially, fluid exchange between the interstitium and the local microvasculature. We solve the mathematical equations in two dimensions by the finite element method (FEM). The finite element implementation is validated against an exact analytical solution that is derived in the appendix. Realistic input tissue properties from the literature are used in conjunction with FEM modelling to conduct several computational experiments. The results of these lead to the following conclusions: (i) different hypothetical flow mechanisms lead to different patterns of strain relaxation with time; (ii) representative tissue properties show fluid drainage into the local microvasculature to be the dominant flow-related stress/strain relaxation mechanism; (iii) the relaxation time of strain in solid tumours due to drainage into the microvasculature is on the order of 5-10 s; (iv) under realistic applied pressure magnitudes, the magnitude of the strain relaxation can be as high as approximately 0.4% strain (4000 microstrains), which is well within the range of strains measurable by elastography.