Department of Mechanical Engineering, University of California, Berkeley, USA.
Department of Radiology and Biomedical Imaging, University of California, San Francisco, USA.
Ann Biomed Eng. 2018 Aug;46(8):1128-1145. doi: 10.1007/s10439-018-2027-5. Epub 2018 Apr 24.
We describe a patient-specific simulation based investigation on the role of Circle of Willis anatomy in cardioembolic stroke. Our simulation framework consists of medical image-driven modeling of patient anatomy including the Circle, 3D blood flow simulation through patient vasculature, embolus transport modeling using a discrete particle dynamics technique, and a sampling based approach to incorporate parametric variations. A total of 24 (four patients and six Circle anatomies including the complete Circle) models were considered, with cardiogenic emboli of varying sizes and compositions released virtually and tracked to compute distribution to the brain. The results establish that Circle anatomical variations significantly influence embolus distribution to the six major cerebral arteries. Embolus distribution to MCA territory is found to be least sensitive to the influence of anatomical variations. For varying Circle topologies, differences in flow through cervical vasculature are observed. This incoming flow is recruited differently across the communicating arteries of the Circle for varying anastomoses. Emboli interact with the routed flow, and can undergo significant traversal across the Circle arterial segments, depending upon their inertia and density ratio with respect to blood. This interaction drives the underlying biomechanics of embolus transport across the Circle, explaining how Circle anatomy influences embolism risk.
我们描述了一种基于患者特定模拟的研究，探讨了 Willis 环解剖结构在心源性脑栓塞中的作用。我们的模拟框架包括基于医学图像的患者解剖结构建模，包括 Willis 环，通过患者血管进行的 3D 血流模拟，使用离散粒子动力学技术的栓子运输建模，以及基于抽样的方法来纳入参数变化。总共考虑了 24 个模型（四个患者和六个包括完整 Willis 环的 Circle 解剖结构），通过虚拟释放和跟踪不同大小和组成的心源性栓子，计算其向大脑的分布情况。结果表明，Willis 环解剖结构的变化显著影响栓子向大脑的六大主要动脉的分布。发现 MCA 区域的栓子分布对解剖结构变化的影响最小。对于不同的 Willis 环拓扑结构，观察到颈血管中的血流差异。这种进入的血流通过 Willis 环的交通动脉以不同的方式募集，对于不同的吻合，差异较大。栓子与流经的血流相互作用，并且可以根据其相对于血液的惯性和密度比，在 Willis 环的动脉段中发生显著的穿越。这种相互作用驱动了栓子在 Willis 环中的传输的基础生物力学，解释了 Willis 环解剖结构如何影响栓塞风险。
