Description:

This example illustrates the blood flow calculation in a model of the circle of Willis reconstructed from contrast-enhanced MRA images, using a region growing algorithm.

The following images show some of the image processing stages.

The next images show the reconstructed arterial tree from different view points

The next two images show how contours of geodesic distance to a user-specified source point can be used to cut the geometrical models along these contours.

The following images show the final geometrical model and the generated finite element grid.

The next three images show the calculated wall shear stress distribution from three different view-points.

Finally the next two images illustrate how CFD calculations could be used for planning interventional procedures. In this case the occlusion of a cerebral artery is simulated and the new flow redistribution and flow patterns are obtained. The figures below show some instantaneous streamlines before and after the occlusive maneuver has been performed.

Observations:

• Fairly complex geometrical models of the circle of Willis have been constructed from MRA images.
• Flow redistribution in cerebral arteries is difficult to predict due to the redundancy of the circle of Willis. CFD calculations provide a way of achieving this.
• Due to the large anatomical variability between individuals, patient-specific modeling is required for planning of surgical and interventional procedures.