A Comparative Study of Middle Cerebral Artery Hemodynamics Pre- and Post-Clipping of Cerebral Aneurysm
Authors: Davidson Haleigh , Scardino Brooke , Hollingsworth Luke , Thibbotuwawa Gamage Peshala , Taebi Amirtahà 
Published: February 2024

Abstract
Cerebral aneurysms (CAs), also referred to as brain or intracranial aneurysms, are potentially life-threatening cerebrovascular conditions where a weakened blood vessel in the brain bulges or protrudes over time. CAs pose a serious health concern if left untreated, as they can lead to rupture, permanent neurological deficit, and fatal aneurysmal subarachnoid hemorrhage. Currently, the most common way to treat aneurysms is surgical clipping, an approach where blood flow to the aneurysm is blocked by a permanently placed clip on the artery. However, not all aneurysms are identical; thus, there has been a need for patient-specific treatment options, a method where each aneurysm is treated based on its individual characteristics. This method allows for a more accurate treatment plan that can be tailored for each patient. In that regard, computational fluid dynamics (CFD) modeling can offer insights to predict how different treatment procedures will affect cerebral hemodynamics. More specifically, during treatment planning, patient-specific CFD modeling of blood flow can aid in further understanding the pathophysiology of CAs and assess aneurismal flow in a range of scenarios and physiological conditions. The goal of this pilot study was to investigate the flow characteristics and hemodynamic parameters in cerebral arteries before and after neurosurgical clipping treatments. For this purpose, two patient-specific cerebral artery geometries were selected from a dataset created by the @neurIST project. Each geometry included at least one aneurysm at the middle cerebral artery bifurcation. Open-source software, ParaView and OpenFlipper, was used to construct and smooth the 3D models, i.e., computational models. A companion model was also created for each geometry by removing the aneurysm from the original geometry and was used as the post-clipping artery model. Tetrahedral mesh elements were then generated and CFD simulations were conducted in SimVascular. Finally, the simulation results were post-processed in ParaView to visualize and compare the blood velocity profile, secondary flow, flow streamline, and wall shear stress in the computational models with and without aneurysm (corresponding to pre- and post-clipping). Results showed that the clipping treatment led to changes in the velocity profiles, secondary flow structures, and wall shear stress in the middle cerebral artery. In conclusion, our results suggest that employing CFD modeling to simulate blood flow in patient-specific cerebral arteries can assist in predicting hemodynamic parameters prior to treatment, thus facilitating more tailored planning for each individual patient’s treatment. This, in turn, can potentially reduce the risks of serious complications and improve clinical outcomes. To further advance this research, future directions could involve exploring additional models of cerebral aneurysms, incorporating more realistic boundary conditions, and validating the current simulation results.