Abstract：
Thrombosis is an important contributor to cerebral aneurysm growth and progression. A number of sophisticated multiscale and multiphase in silico models have been developed with a view towards interventional planning. Many of these models are able to account for clotting outcomes, but do not provide detailed insight into the role of flow during clot development. In this study, we present idealised, two-dimensional in silico cerebral fibrin clot model based on computational fluid dynamics (CFD), biochemical modelling and variable porosity, permeability, and diffusivity. The model captures fibrin clot growth in cerebral aneurysms over a period at least 1000 s in five different geometries. The fibrin clot growth results were compared to an experiment presented in literature. The biochemistry was found to be more sensitive to mesh size compared to the haemodynamics, while larger timesteps overpredicted clot size in pulsatile flow. When variable diffusivity was used, the predicted clot size was 25.4% lesser than that with constant diffusivity. The predicted clot size in pulsatile flow was 14.6% greater than in plug flow. Different vortex modes were observed in plug and pulsatile flow; the latter presented smaller intermediate modes where the main vortex was smaller and less likely to disrupt the growing fibrin clot. Furthermore, smaller vortex modes were seen to support fibrin clot propagation across geometries. The model clearly demonstrates how the growing fibrin clot alters vortical structures within the aneurysm sac and how this changing flow, in turn, shapes the growing fibrin clot.
摘要：
血栓形成是脑动脉瘤生长和进展的重要因素。为了进行介入计划，已经开发了许多复杂的多尺度和多相计算机模型。这些模型中的许多能够解释凝血结果，但不提供详细的洞察流量在血块发展过程中的作用。在这项研究中,我们理想化的呈现，基于计算流体力学(CFD)的二维模拟脑内纤维蛋白凝块模型,生化建模和可变孔隙率，渗透性,和扩散性。该模型在至少1000s的时间内捕获了五种不同几何形状的脑动脉瘤中的纤维蛋白凝块生长。将纤维蛋白凝块生长结果与文献中提出的实验进行比较。与血液动力学相比，发现生物化学对网眼大小更敏感，而较大的时间步长过度预测了脉动流中的凝块大小。当使用可变扩散率时，预测的凝块大小比具有恒定扩散率的凝块大小小25.4%。脉冲流中的预测凝块尺寸比活塞流中的大14.6%。在塞流和脉动流中观察到不同的涡流模式；后者呈现较小的中间模式，其中主涡流较小，并且不太可能破坏正在生长的纤维蛋白凝块。此外，观察到较小的涡流模式支持纤维蛋白凝块在几何形状上的传播。该模型清楚地展示了生长的纤维蛋白凝块如何改变动脉瘤囊内的涡旋结构，以及这种变化的流量如何，反过来,塑造正在生长的纤维蛋白凝块。
