Enhancing Hemodynamic Parameter Estimations: Nonlinear Blood Behavior in 4D Flow MRI

Hemodynamic parameters have been estimated assuming a Newtonian constant viscosity, even when blood exhibits shear-thinning behavior. This article investigates the influence of blood rheology and hematocrit percentage on estimating Wall Shear Stress (WSS) and Energy Loss ($E_L$) at different time instants of the cardiac cycle, as well as the Oscillatory Shear Index (OSI). We specifically focus on a hematocrit-dependent power-law non-Newtonian model, considering a wide range of hematocrit values. The rheological parameters are obtained from experimentally fitted data reported previously. This study contributes to understanding the impact of blood rheology on hemodynamic parameter estimations using both in-silico and in-vivo aortic 4D Flow magnetic resonance images. Across all cases, we systematically compared WSS, $E_L$, and OSI parameters using Newtonian and power-law models, highlighting the crucial role of blood rheology in accurately assessing cardiovascular diseases.