Effect of Local Coil Density on Blood Flow Stagnation in Densely Coiled Cerebral Aneurysms: A Computational Study Using a Cartesian Grid Method
Effect of Local Coil Density on Blood Flow Stagnation in Densely Coiled Cerebral Aneurysms: A Computational Study Using a Cartesian Grid Method
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DOI：
10.1115/1.4039150
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发表时间：
2018-04-01
影响因子：
1.7
通讯作者：
Wada, Shigeo
中科院分区：
文献类型：
--
作者：
Otani, Tomohiro;Shindo, Takuya;Wada, Shigeo
动脉瘤复发是脑动脉瘤线圈栓塞后最重要的问题。足够的填充密度（PD）和线圈均匀性被认为是实现充分的血流停滞所必需的，这可以降低动脉瘤复发的风险。然而，线圈分布对流动停滞程度的影响，特别是在密集填料（高PD）的情况下，得到的关注较少。因此，动脉瘤复发的原因，尽管密集的包装仍然是一个悬而未决的问题。本研究的主要目的是评估局部线圈密度对致密卷曲动脉瘤血流停滞程度的影响。为此，我们开发了一个鲁棒的计算框架，使用笛卡尔网格方法来确定血流，通过该计算框架，可以灵活地使用隐式函数处理螺旋状动脉瘤中的复杂流体路径。该工具使我们能够在临床上足够的PD下，对每个动脉瘤进行两种患者特定几何形状的50个线圈分布模式的血流分析。结果表明，动脉瘤内致密的填塞不一定能完全阻断流入动脉瘤内的液体和颈部区域形成的局部血流，其强度与该局部PD呈负相关。这一发现提示，颈部区域的局部线圈密度仍然在干扰剩余的局部血流方面发挥重要作用，这可能阻止整个动脉瘤囊内血栓的形成，增加动脉瘤再生和随后复发的风险。
Aneurysm recurrence is the most critical concern following coil embolization of a cerebral aneurysm. Adequate packing density (PD) and coil uniformity are believed necessary to achieve sufficient flow stagnation, which decreases the risk of aneurysm recurrence. The effect of coil distribution on the extent of flow stagnation, however, especially in cases of dense packing (high PD), has received less attention. Thus, the cause of aneurysm recurrence despite dense packing is still an open question. The primary aim of this study is to evaluate the effect of local coil density on the extent of blood flow stagnation in densely coiled aneurysms. For this purpose, we developed a robust computational framework to determine blood flow using a Cartesian grid method, by which the complex fluid pathways in coiled aneurysms could be flexibly treated using an implicit function. This tool allowed us to conduct blood flow analyses in two patient-specific geometries with 50 coil distribution patterns in each aneurysm at clinically adequate PD. The results demonstrated that dense packing in the aneurysm may not necessarily block completely the inflow into the aneurysm and local flow that formed in the neck region, whose strength was inversely related to this local PD. This finding suggests that local coil density in the neck region still plays an important role in disturbing the remaining local flow, which possibly prevents thrombus formation in a whole aneurysm sac, increasing the risk of aneurysm regrowth and subsequent recurrence.