Finite-Element Extrapolation of Myocardial Structure Alterations Across the Cardiac Cycle in Rats.
Finite-Element Extrapolation of Myocardial Structure Alterations Across the Cardiac Cycle in Rats.
复制标题
大鼠整个心脏周期心肌结构变化的有限元外推。
DOI：
10.1115/1.4031419
复制
发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Hsu,EdwardW
中科院分区：
文献类型：
--
作者：
DavidGomez,Arnold;Bull,DavidA;Hsu,EdwardW
心肌微结构是心脏机械功能的关键方面。整个心动周期的自然心肌变形引起可测量的结构改变，其在疾病状态中变化。扩散张量磁共振成像（DT-MRI）已成为心肌结构分析的首选工具。然而，在3D和时间上获得整个器官的综合结构信息以用于对象特定的检查从根本上受到扫描时间的限制。因此，对一组大鼠心脏进行特定受试者的有限元（FE）分析，以将一组初始DT-MRI外推至心动周期的其余部分。材料对称性（各向同性、横向各向同性和正交各向异性）、结构输入和翘曲方法的影响通过比较模拟预测与体内MRI位移测量和在松弛、膨胀和挛缩状态下的离体心脏制备的DT-MRI来观察。总体而言，结果表明，虽然心室容积和周向应变在很大程度上独立于模拟策略，但随着材料模型的复杂性，结构改变预测通常会得到改善，这也增强了扭转和径向应变预测。此外，而特定主题的横向各向同性模型产生的纤维结构的变化最准确的描述，正交各向异性模型最好地捕捉在片材结构的变化。这些发现强调了需要特定于受试者的输入数据，包括结构，以推断整个心动周期的DT-MRI测量值。
Myocardial microstructures are responsible for key aspects of cardiac mechanical function. Natural myocardial deformation across the cardiac cycle induces measurable structural alteration, which varies across disease states. Diffusion tensor magnetic resonance imaging (DT-MRI) has become the tool of choice for myocardial structural analysis. Yet, obtaining the comprehensive structural information of the whole organ, in 3D and time, for subject-specific examination is fundamentally limited by scan time. Therefore, subject-specific finite-element (FE) analysis of a group of rat hearts was implemented for extrapolating a set of initial DT-MRI to the rest of the cardiac cycle. The effect of material symmetry (isotropy, transverse isotropy, and orthotropy), structural input, and warping approach was observed by comparing simulated predictions against in vivo MRI displacement measurements and DT-MRI of an isolated heart preparation at relaxed, inflated, and contracture states. Overall, the results indicate that, while ventricular volume and circumferential strain are largely independent of the simulation strategy, structural alteration predictions are generally improved with the sophistication of the material model, which also enhances torsion and radial strain predictions. Moreover, whereas subject-specific transversely isotropic models produced the most accurate descriptions of fiber structural alterations, the orthotropic models best captured changes in sheet structure. These findings underscore the need for subject-specific input data, including structure, to extrapolate DT-MRI measurements across the cardiac cycle.