  Numerical simulations have been extensively used in the past two decades for
the study of intracranial aneurysms (IAs), a dangerous disease that occurs in
the arteries that reach the brain. They may affect up to 10 % of the world's
population, with up to 50 % mortality rate, in case of rupture. Physically, the
blood flow inside IAs should be modeled as a fluid-solid interaction problem.
However, the large majority of those works have focused on the hemodynamics of
the intra-aneurysmal flow, while ignoring the wall tissue's mechanical response
entirely, through rigid-wall modeling, or using limited modeling assumptions
for the tissue mechanics. One of the explanations is the scarce data on the
properties of IAs walls, thus limiting the use of better modeling options.
Unfortunately, this situation is still the case, thus our present study
investigates the effect of different modeling approaches to simulate the motion
of an IA. We used three hyperelastic laws and two different ways of modeling
the wall thickness and tissue mechanical properties -- one assumed that both
were uniform while the other accounted for the heterogeneity of the wall by
using a "hemodynamics-driven" approach in which both thickness and material
constants varied spatially with the cardiac-cycle-averaged hemodynamics.
Pulsatile numerical simulations, with patient-specific vascular geometries
harboring IAs, were carried out using the one-way fluid-solid interaction
solution strategy, in which the blood flow is solved and applied as the driving
force of the wall motion. We found that different wall morphology models yield
smaller absolute differences in the mechanical response than different
hyperelastic laws. Furthermore, the stretch levels of IAs walls were more
sensitive to the hyperelastic and material constants than the stress. These
findings could be used to guide modeling decisions on IA simulations.
