Rationale and objectives: Previous studies of aneurysm flow dynamics based on three-dimensional (3D) rotational angiography (RA) images were limited to aneurysms with a single route of blood inflow. However, aneurysms of the circle of Willis frequently involve locations with more than one source of inflow, such as aneurysms of the anterior communicating artery. The highest resolution images of cerebral vessels are from RA images, but this technique is limited to visualizing only one route of inflow at a time, leaving a significant limitation in the application of 3DRA image sets for clinical studies of patient-specific computational fluid dynamics (CFD) simulations. In this report, subject-specific models of cerebral aneurysms with multiple avenues of flow are constructed from RA images by using a novel combination of image co-registration and surface merging techniques.
Materials and methods: RA images are obtained by means of contrast injection in each vessel that provides inflow to the aneurysm. Anatomic models are constructed independently of each of these vascular trees and fused together into a single model. The model is used to construct a finite element grid for CFD simulations of hemodynamics.
Results: Three examples of patient-specific models are presented: an anterior communicating artery aneurysm, a basilar tip aneurysm, and a model of an entire circle of Willis with five coincident aneurysms. The method is evaluated with a numeric phantom of an aneurysm in the anterior communicating artery.
Conclusion: These examples show that this new technique can be used to create merged network numeric models for CFD modeling. Furthermore, intra-aneurysmal flow patterns are influenced strongly by merging of the two inflow streams. This effect decreases as distance from the merging streams increases.