  Typical approaches to patient-specific hemodynamic studies of cerebral
aneurysms use image based computational fluid dynamics (CFD) and seek to
statistically correlate parameters such as wall shear stress (WSS) and
oscillatory shear index (OSI) to risk of growth and rupture. However, such
studies have reported contradictory results, emphasizing the need for in-depth
comparisons of volumetric experiments and CFD. In this work, we conducted
tomographic particle velocimetry experiments using two patient-specific
cerebral aneurysm models (basilar tip and internal carotid artery) under
pulsatile flow conditions and processed the particle images using Shake the Box
(STB), a particle tracking method. The STB data was compared to that obtained
from in vivo 4D flow MRI and CFD. Although qualitative agreement of flow
pathlines across modalities was observed, each modality maintained notably
unique spatiotemporal distributions of low normalized WSS regions. Analysis of
time averaged WSS (TAWSS), OSI, and Relative Residence Time (RRT) demonstrated
that non-dimensional parameters, such as OSI, may be more robust to the varying
assumptions, limitations, and spatial resolutions of each subject and modality.
These results suggest a need for further multi-modality analysis as well as
development of non-dimensional hemodynamic parameters and correlation of such
metrics to aneurysm risk of growth and rupture.
