Hemodynamic Characteristics in an Intracranial Aneurysm Model using Non-Newtonian Blood Analog: A Critical Step from Lab to Clinic

Blood presents non-Newtonian properties while is often assumed as Newtonian in quantifying hemodynamics in intracranial aneurysms (IAs) in previous studies, which may introduce errors and limit applications in the clinic. To accurately quantify the hemodynamic characteristics in IAs, this study was to develop an experimentally validated computational fluid dynamics (CFD) IA model using non-Newtonian blood analog with shear-thinning properties. First, non-isothermal and shear thinning properties of blood were identified via. measuring corresponding viscosities under designated shear rates and temperatures, which provides a reference for prepared non-Newtonian blood analog. The analog was used to carry out particle image velocimetry (PIV) measurements to quantify flow fields in a 3D physical IA model. Subsequently, using identical viscosities and boundary conditions in PIV test, CFD simulation was proceeded to obtain flow fields in the same IA model. Agreements in flow patterns between CFD and PIV were evaluated to validate the CFD model. Additionally, to evaluate errors induced by often used Newtonian blood, hemodynamics under conditions of simplified Newtonian model and realistic non-Newtonian model were compared using the validated CFD model. Results indicate the generated blood analog well matches blood non-Newtonian properties, by comparing with the referred blood. Comparisons in blood flowrates, velocities, and vortex features show good agreements between PIV and CFD, demonstrating the CFD model was developed. Although differences of absolute values were insignificant between Newtonian and non-Newtonian bloods, with respect to wall shear stress and oscillatory shear index (OSI), the Newtonian modeling underestimates WSS and OSI in most regions on the sac, especially regions with high OSI which may mislead hemodynamic assessments on IA pathophysiology. The developed CFD IA model with non-Newtonian blood properties filled a critical knowledge gap from lab to clinic, which can be further adopted to accurately identify hemodynamics on IA pathobiology.