Computational Fluid Dynamics and Phase-Contrast Magnetic Resonance of Normal Cerebral Arteries

Detailed knowledge of the hemodynamic conditions in normal cerebral arteries is important for a better understanding of the underlying mechanisms leading to the initiation and progression of cerebrovascular diseases. The goal of our research is to characterize the hemodynamic patterns in the major cerebral arteries of normal subjects using 4D phase-contrast magnetic resonance imaging (PC-MR) and image-based computational fluid dynamics (CFD), and to assess the consistency of the flow patterns determined by these two techniques. Time-resolved 4D PC-MR images of the cerebral arteries at the level of the Circle of Willis were acquired on three normal subjects and corresponding subject-specific CFD models were constructed. Visualizations of the flow fields show that qualitatively, the major flow structures, swirling flows, flow directions in communicating arteries, etc. observed in the PC-MR images and the CFD calculations are consistent. However, each technique has limitations that introduce differences between the corresponding flow fields. This paper discusses these differences in order to better interpret the results obtained with each technique, and to be aware of the regions along the arteries where each technique is expected to over simplify the velocity patterns or yield under or over estimations of the velocity and wall shear stress magnitudes.