Phase contrast MRI in intracranial aneurysms

Intracranial aneurysms are outpouchings of intracranial arteries that cause brain hemorrhage after rupture. Unruptured aneurysms can be treated but the risk of treatment may outweigh the risk of rupture. Local intra-aneurysmal hemodynamics can contribute substantially to the rupture risk estimation of the individual aneurysm. The only technique capable of measuring three-dimensional flow patterns over time in vivo is time-resolved three-dimensional phase contrast MRI (PC-MRI). In this thesis in vitro PC-MRI was compared with particle image velocimetry and computational fluid dynamics (CFD). In vivo PC-MRI was compared with patient-specific CFD in eight aneurysms. Two acquisition strategies to improve PC-MRI were tested: 1) PC MRI in combination with k-t BLAST was compared with PC-MRI in combination with parallel imaging. 2) PC-MRI at 7T was compared with PC-MRI at 3T. Furthermore, a novel algorithm to calculate wall shear stress from PC-MRI data is presented, tested i This thesis demonstrates that PC-MRI can be used to quantify and visualize intra-aneurysmal flow patterns and wall shear stress.