Hemodynamics of unruptured and ruptured middle cerebral artery aneurysms based on fluid-structure interaction

In the past, the study on the hemodynamics of intracranial aneurysms(IAs) mostly ignored the elasticity of the arterial wall. We investigated the hemodynamics of ruptured and unruptured intracranial aneurysms using fluid-structure interaction (FSI) to enhance simulation realism and offer a hemodynamic framework for predicting aneurysm rupture risk.

A detailed analysis was performed on 26 intracranial aneurysms (IAs) at the middle cerebral artery bifurcation, including 13 ruptured and 13 unruptured cases. Utilizing FSI analysis, the aim was to discern the distinguishing features of ruptured IAs. The study explored changes in important hemodynamic factors, including wall shear stress (WSS), oscillatory shear index (OSI), displacement deformation(DIS), von Mises stress (VMS), and relative residence time (RRT) of the arterial wall.

Ruptured IAs had higher maximum time-averaged OSI, RRT, DIS, VMS. During systolic blood period, the average DIS and the maximum DIS, are all significantly higher than that of unruptured aneurysms. Moreover, the displacement deformation area at the ruptured IA was both more concentrated and larger. TAWSS does not differ between ruptured and unruptured aneurysms; however, WSS magnitude significantly varies between the aneurysm body and the parent artery. The aneurysm body's WSS is lower than that of the parent artery. All areas of aneurysm with large displacement deformation correspond to low WSS. The average time-averaged DIS in all aneurysms showed a negative correlation (r = -0.451) with the average time-averaged WSS.

Large DIS, RRT, VMS, and high OSI of the aneurysm may pose as risk factors contributing to aneurysm rupture. In clinical scenarios where simulation is employed, encountering similar cases necessitates a prioritization of diagnosis and treatment.