Circle of Willis Flow Analysis

    The Circle of Willis (CoW) is located at the base of the brain providing the primary vascular link to the heart. The communicating arteries of the CoW form a bridge between the cerebral arteries and are thought to maintain the blood supply should problems occur. However, congenital variations can lead to uncertainty with this hypothesis. In this case study realistic numerical representations of the vessels of interest are obtained using ScanIP+FE to convert contrast enhanced MRI scan images into accurate CFD meshes. The role of the communicating arteries is then investigated with blood flow simulation.

Image Processing

     A contrast enhanced MRI scan of an adult male head was used to provide the image data required to generate the model of the CoW. A variety of ScanIP's semi-automated and manual segmentation tools were used to isolate the complex structure and provide the baseline CoW model. A number of problematic downstream vascular features (aneurism and stenosis) were then created using ScanIP's 3D editing tools, providing a set of models with which to analyse their effect on blood flow through the communicating arteries.

Meshing

       For comparative simulation, CFD meshes where produced directly from the CoW model. All meshes were of equally high quality, with maximum element aspect ratios of less than 2. Mesh sensitivity analyses were carried out on a range of mesh densities to determine the optimum number of elements to be used for the simulation. Meshes were exported in the dedicated COMSOL format provided by ScanIP+FE allowing their straightforward import into the solver.