Wall motion and hemodynamics in intracranial aneurysms

The optimal management of unruptured aneurysms is controversial and current decision making derived from the International Study of Unruptured Intracranial Aneurysms is based on aneurysm size and location. Wall shear stress triggers biomechanical responses of endothelial cells, which are associated to cerebral aneurysm initiation, progress and bleeding. Early identification of potential risk factors may contribute to decide the treatment and improve patient care. Previous studies have shown associations between high aneurysm wall shear stress values and both elevated risk of rupture and regions of aneurysm growing. Based on the assumption that damaged regions of the endothelium have different mechanical properties, regions with differentiated wall displacement amplitudes are expected. A previous approach based on the analysis of bidimensional dynamic tomographic angiography had been designed to investigate those correlations, but its main limitation was that wall motion was measured in a selected plane. In this work a high time and spatial resolution four-dimensional computerized tomographic angiography image of an anterior communicating artery aneurysm was acquired and analyzed to identify and characterize wall motion and intra aneurysmal hemodynamics. All three-dimensional images were filtered and segmented and wall displacement was estimated within the aneurysm sac and compared to wall shear stress distributions from patient-specific unsteady finite element blood flow simulations. Regions were high wall motion was detected are in close agreement with regions were high wall shear stress values were obtained from the numerical blood flow simulations.