Evaluating the Impact of Domain Boundaries on Hemodynamics in Intracranial Aneurysms within the Circle of Willis

Abstract

Hemodynamic simulations are increasingly used to study vascular diseases such as Intracranial Aneurysms (IA) and to further develop treatment options. However, due to limited data, certain aspects must rely on heuristics, especially at the simulation’s distal ends. In the literature, Murray’s Law is often used to model the outflow split based on vessel cross-section area; however, this poses challenges for the communicating arteries in the Circle of Willis (CoW). In this study, we contribute by assessing the impact of Murray’s Law in patient-specific geometries featuring IA at the posterior communication. We simulate different domain extensions representing common modelling choices and establish Full CoW simulations as a baseline to evaluate the effect of these modelling assumptions on hemodynamic indicators, focusing on IA growth and rupture-related factors such as the Wall Shear Stress (WSS) and Oscillatory Shear Index (OSI). Our findings reveal qualitative alterations in hemodynamics when not modeling posterior communication. Comparisons between computing the anterior circulation and computing the whole Circle of Willis reveal that quantitative changes in WSS may reach up to 80%, highlighting the significance of modelling choices in assessing IA risks and treatment strategies.

AnXplore: a comprehensive fluid-structure interaction study of 101 intracranial aneurysms

“…Later, challenges tried focusing on specific aspects of the pipeline, underscoring for instance the significant impact of geometry segmentation processes (Berg et al, 2018;Paritala et al, 2023). Boundary conditions have also been pointed out as crucial aspects of the simulation setting (Jeken-Rico et al, 2024;Nozaleda et al, 2024). Indeed, 25% inflow rate variations have been reported to cause TAWSS variations in the range of 30% (Øyvind et al, 2013;Nozaleda et al, 2024).…”

“…The development of CFD simulations of IAs has raised multiple scientific challenges, ranging from the consistent generation of meshes for intricate vessel geometries to the resolution of coupled systems of equations involving adequate boundary conditions and multiple parameters (Janiga et al, 2015;Jeken-Rico et al, 2024). Among the remaining research goals stands the modelling of the complex interaction between the blood flow and surrounding vessels through Fluid-Structure Interaction (FSI).…”