Numerical study on low-density lipoprotein transport in intracranial aneurysms and its association with wall enhancement.

The frequent detection of wall enhancement by vessel wall imaging in unstable or ruptured intracranial aneurysms (IAs) implies the potential involvement of blood substance transport in the pathogenesis of IAs. In this study, we developed a new method for simulating the transport of low-density lipoprotein (LDL) in IAs. The method was characterized by the coupled solution of LDL transport behaviors in lumen, across endothelium, and within vessel wall, and the incorporation of a sub-model that accounts for the combined effect of wall shear stress (WSS) magnitude and oscillatory shear index (OSI) on endothelial permeability to LDL. Numerical simulations were conducted on the IAs of four patients with clinically confirmed wall enhancement status. Obtained results demonstrated the propensity of IAs for enhanced LDL deposition on the lumen surface and LDL accumulation within the wall compared to normal cerebral arteries. Notably, the spatial distributions of high LDL concentration on the lumen surface and within the vessel wall were not always consistent, indicating regional variations in biomechanical factors facilitating intraluminal retention and transmural transport of LDL. Furthermore, the IAs with wall enhancement exhibited remarkably larger area ratios of wall regions exposed to high LDL concentration than those without wall enhancement. Relatively, the area ratios of low WSS and high OSI were less predictive of aneurysm wall enhancement. These findings underscore the potential value of investigating mass transport over general hemodynamic behaviors in classifying the pathological state or assessing the risk of IAs.