| Popis: |
Despite available clinical evidence, several underlying issues regarding the connection between Circle of Willis anatomy and stroke remain unclear. Embolisms comprise a major cause of ischemic stroke, and discerning how emboli traverse the complex cerebral arterial network is challenging. Here we describe a patient-specific simulation based investigation on the role of Circle anatomy in cardioembolic stroke. Our simulation framework consists of medical image-driven modeling of patient anatomy including the Circle, simulation of 3D blood flow through patient vasculature, embolus transport modeling using a discrete particle dynamics technique, and a sampling based approach to incorporate parametric variations. Five Circle anatomical variants are identified using ranking statistics applied to occurrence frequency data in literature, for each variant. 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 middle brain 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. |
