Wall Shear Rate method validation through multi-physics simulations

Wall Shear Stress (WSS), i.e. the tangential force that blood applies to the inner layer of the vessel wall, is associated with arterial remodeling and important cardiovascular diseases like the formation of atherosclerotic plaques. In simple, uniaxial flows, WSS can be derived as the blood viscosity multiplied by the Wall Shear Rate (WSR), i.e. the velocity gradient evaluated in the radial direction. The WSR is typically estimated by measuring the velocity of the blood in the vessel center and by assuming a parabolic velocity profile (Poiseuille model). Unfortunately, this model produces inaccurate results since it does not account for the complex flow configuration present in the vessel. In a different approach, the actual flow profile is measured instantaneously through a multigate technique, but the clutter corrupts the profile in proximity to the wall, i.e. where the WSR should be evaluated, so that the profile should be reconstructed. In this work, realistic multi-physics simulations of a patient-specific carotid bifurcation are used to assess the accuracy of a 2-step method for profile reconstruction and WSR measurement. The estimated WSR matches the model ground-truth with an accuracy of about 10%.