Introduction
Hemodynamics is thought to play a very important role in the initiation, growth, and rupture of intracranial aneurysms. The
purpose of our study was to perform in vivo hemodynamic analysis of unruptured intracranial aneurysms of magnetic resonance
fluid dynamics using time-resolved three-dimensional phase-contrast MRI (4D-Flow) at 1.5 T and to analyze relationships between
hemodynamics and wall shear stress (WSS) and oscillatory shear index (OSI).
Methods
This study included nine subjects with 14 unruptured aneurysms. 4D-Flow was performed by a 1.5-T magnetic resonance scanner
with a head coil. We calculated in vivo streamlines, WSS, and OSI of intracranial aneurysms based on 4D-Flow with our software.
We evaluated the number of spiral flows in the aneurysms and compared the differences in WSS or OSI between the vessel and
aneurysm and between whole aneurysm and the apex of the spiral flow.
Results
3D streamlines, WSS, and OSI distribution maps in arbitrary direction during the cardiac phase were obtained for all intracranial
aneurysms. Twelve aneurysms had one spiral flow each, and two aneurysms had two spiral flows each. The WSS was lower and the
OSI was higher in the aneurysm compared to the vessel. The apex of the spiral flow had a lower WSS and higher OSI relative
to the whole aneurysm.
Conclusion
Each intracranial aneurysm in this study had at least one spiral flow. The WSS was lower and OSI was higher at the apex of
the spiral flow than the whole aneurysmal wall.
Keywords Intracranial aneurysm - Wall shear stress - Oscillatory shear index - Cine phase-contrast MR imaging - Magnetic resonance fluid dynamics