Intracranial Stents Being Modeled as a Porous Medium: Flow Simulation in Stented Cerebral Aneurysms
Intracranial Stents Being Modeled as a Porous Medium: Flow Simulation in Stented Cerebral Aneurysms
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DOI：
10.1007/s10439-010-0200-6
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发表时间：
2011-02-01
影响因子：
3.8
通讯作者：
Stergiopulos, N.
中科院分区：
文献类型：
--
作者：
Augsburger, L.;Reymond, P.;Stergiopulos, N.
颅内动脉瘤可采用分流器治疗，也可采用支架和线圈联合治疗。数值模拟可以评估动脉瘤流动的复杂性。血管内装置呈现相当密集和精细的支撑网络，增加了网格的复杂性。我们提出了一种替代策略，该策略基于将设备建模为多孔介质。使用传统的临床设置重建了两个特定患者的动脉瘤数据集。动脉瘤的选择使动脉瘤内的血流在一个被剪切驱动，在另一个被惯性驱动。支架及其多孔介质类似物被放置在动脉瘤颈部。采用生理流动和标准边界条件。通过分析动脉瘤内的速度、涡度和剪切速率大小以及动脉瘤表面的壁面剪切应力（WSS），对两种方法进行了比较。在没有装置的情况下也进行了模拟计算。剪切驱动和惯性驱动的平均流量降幅分别达到76%和41%。通过对两种方法的比较，结果表明两种方法在流型和流量上具有显著的相似性。WSS、等速面和横断面上的速度具有较好的一致性。动脉瘤速度的均方根误差为20%，动脉瘤剪切率的均方根误差为30.6%，动脉瘤涡量的均方根误差为47.4%。动脉瘤表面WSS达到20.6%。这种方法的优点在于易于实现和节省了计算时间。多孔介质方法预测的结果与真实支架几何模型比较好，可以预测装置对动脉瘤内血流的主要影响，从而便于分析。
Intracranial aneurysms may be treated by flow diverters, alternatively to stents and coils combination. Numerical simulation allows the assessment of the complex nature of aneurismal flow. Endovascular devices present a rather dense and fine strut network, increasing the complexity of the meshing. We propose an alternative strategy, which is based on the modeling of the device as a porous medium. Two patient-specific aneurysm data sets were reconstructed using conventional clinical setups. The aneurysms selection was done so that intra-aneurismal flow was shear driven in one and inertia driven in the other. Stents and their porous medium analog were positioned at the aneurysm neck. Physiological flow and standard boundary conditions were applied. The comparison between both approaches was done by analyzing the velocity, vorticity, and shear rate magnitudes inside the aneurysm as well as the wall shear stress (WSS) at the aneurysm surface. Simulations without device were also computed. The average flow reduction reaches 76 and 41% for the shear and inertia driven flow models, respectively. When comparing the two approaches, results show a remarkable similarity in the flow patterns and magnitude. WSS, iso-velocity surfaces and velocity on a trans-sectional plane are in fairly good agreement. The root mean squared error on the investigated parameters reaches 20% for aneurysm velocity, 30.6% for aneurysm shear rate, and 47.4% for aneurysm vorticity. It reaches 20.6% for WSS computed on the aneurysm surface. The advantages of this approach reside in its facility to implement and in the gain in computational time. Results predicted by the porous medium approach compare well with the real stent geometry model and allow predicting the main effects of the device on intra-aneurismal flow, facilitating thus the analysis.