Automatic determination of the dynamic geometry of abdominal aortic aneurysm from MR with application to wall stress simulations

The current surgical intervention criterion for abdominal aortic aneurysm is based on the maximum transverse diameter of the aorta. Recent research advances indicate that a better rupture predictor may be derived from the wall stress, which can be computed with the finite element method. An essential prerequisite for this modelling is an accurate description of the geometry of the aneurysm. We developed an automatic method to derive the dynamic patient-specific aneurysm geometry from non-contrast enhanced MRA balanced turbo field images. The slices of our 2D-scanned volumes are registered onto 3D-scanned volumes to restore spatial coherence. The resulting images are noise-filtered and the enddiastolic volume is segmented with an active objects technique (deformable models). The resulting geometrical model is propagated to the remaining phases using the correlation between grey value profiles on the surface as an external force for the active object. From our segmentations we derived tetrahedral finite element meshes which were used as the input for finite element wall stress simulations.