Influence of vessel roughness on wall shear stress in image-based blood flow modeling

Image-based blood flow modeling provides a unique way to quantify wall shear stress in 3D subject-specific geometric models. These models are constructed from medical images, inevitably using smoothing to compensate for noise and limited resolution. Moreover, the vessel is generally getting rougher due to disease or aging. However, there are few studies on influences of different levels of smoothness/roughness on wall shear stress. From the CT image of a thoracic aorta with aneurysm, we constructed 13 models: 1 original, 6 smoothed, and 6 roughened. Using computational fluid dynamics, we show qualitatively the distribution of wall shear stress varies noticeably with different levels of roughness. However, the maximal percentage difference is about 10% when averaged spatially in banded cross sections. Our study suggests the fidelity of geometry is significant in understanding the localization of wall shear stress, whereas the overall trend is relatively insensitive to the level of smoothness/roughness.