Influence of segmentation on morphological parameters and computed hemodynamics in cerebral aneurysms

This article focuses on the effects of segmentation on cerebral aneurysm's morphological parameters and on blood flow patterns computed using computational fluid dynamics. Segmentation is a non-negligible source of uncertainty that may have a consequent impact on the morphological assessment and the resulting hemodynamical simulations, the latter potentially being a key element in the decision-making therapeutic armamentarium for neuroradiologists and neurosurgeons. From the three patient-specific cases investigated, medical imaging data sets were collected, and four different three-dimensional segmentations were generated by the same senior technician. Morphological parameters were measured, and the aspect ratio was derived. Numerical simulations were performed; flow pattern changes, their impact on wall shear stress (WSS) and their sensitivity within the four reconstructed geometries were analyzed. Aneurysm velocity, vorticity and shear magnitudes were computed and compared. The morphological parameters having the highest variability were the aneurysm lobe dimensions (20 %). The neck length was the second parameter presenting the highest variability (21 %). The neck width variability reached 13.8 %, and the aspect ratio variability reached 14.2 %. The artery height and the artery width presented a variability of 13.7 and 10.8 %, respectively. Finally, the aneurysm depth, aneurysm height and aneurysm width presented variabilities of 12.8, 9.4 and 7.3 %, respectively. Differences in the flow path lines, velocity magnitude, wall shear stress and vorticity are also reported and discussed. The average variability reached 15.6 % for velocity, 25.2 % for vorticity and 25.2 % for shear, these parameters being computed inside the aneurysm. The maximum variability reached 31.0 % for velocity, 54.8 % for vorticity and 58.1 % for shear. A segmentation process reconstructing anatomies that is less sensitive to human intervention would be a future goal worth pursuing.