Cerebral aneurysm rupture is a leading cause of hemorrhagic strokes. Because they are being more frequently diagnosed
before rupture and the prognosis of subarachnoid hemorrhage is poor, clinicians are often required to judge which
aneurysms are prone to progression and rupture. Unfortunately, the processes of aneurysm initiation, growth and rupture
are not well understood. Multiple factors associated to these processes have been identified. Our goal is to investigate
two of them, arterial hemodynamics (using computational fluid dynamics) and the peri-aneurysmal environment, by
studying a group of growing cerebral aneurysms that are followed longitudinally in time.
Six patients with unruptured untreated brain aneurysms which exhibited growth during the observation period were
selected for the study. Vascular models of each aneurysm at each observation time were constructed from the
corresponding computed tomography angiography (CTA) images. Subsequently, models were aligned, and geometrical
differences quantified. Blood flow was modeled with the 3D unsteady incompressible Navier-Stokes equation for a
Newtonian fluid, and wall shear stress distribution and flow patterns were calculated and visualized.
Analysis of the simulations and changes in geometry revealed asymmetric growth patterns and suggests that areas
subject to vigorous flows, i.e. relative high wall shear stress and concentrated streamlines patterns; correspond to regions
of aneurysm growth. Furthermore, in some cases the geometrical evolution of aneurysms is clearly affected by contacts
with bone structures and calcifications in the wall, and as a consequence the hemodynamics is greatly modified. Thus, in
these cases the peri-aneurysmal environment must be considered when analyzing aneurysm evolution.