On the Role of Modeling Choices in Estimation of Cerebral Aneurysm Wall Tension

Estimations of pressure-induced tension in the cerebral aneurysm sac wall may serve as metrics that help stratify patients according to rupture risk. Beyond segmentation of patient-specific aneurysm geometries, many modeling choices may be made in order to numerically estimate pressure-induced aneurysm wall tension. Some of these key choices are: 1) the material model and its parameters (this is unknown at a patient-specific level); 2) whether or not to accommodate bending deformation (membrane versus shell); 3) whether and how much of vasculature to include in domain of analysis; and 4) how to address the lack of zero-pressure geometry (forward versus inverse solution schemes). Often, the focus is on what the best of these modeling choices are. In an ideal world, appropriate modeling choices would be the use of an anisotropic finite elastic model [1–2], shell-like behavior [3], a large enough vasculature in the analysis domain to minimize edge-effects at the aneurysm sac, and an inverse solution scheme [3] to address the pre-deformed nature of the sac under in vivo imaging. But are these rigorous modeling choices really that necessary? Would compromising on these choices translate into significant error in the findings? We submit that, to the extent that the goal is to stratify patients according to sac wall tension, modeling choices are really secondary and will not translate into significant error in our interpretations. The objective of this study is to test the importance of three of these modeling choices — material model, truncation of vasculature in analysis domain and solution scheme (forward versus inverse) — in stratifying aneurysms based on wall tension using aneurysms in a study population.