CFD Analysis Incorporating the Influence of Wall Motion: Application to Intracranial Aneurysms

Abstract

Abstract. Haemodynamics, and in particular wall shear stress, is thought to play a critical role in the progression and rupture of intracranial aneurysms. A novel method is presented that combines image-based wall motion estimation obtained through non-rigid registration with computational fluid dynamics (CFD) simulations in order to provide realistic intra-aneurysmal flow patterns and understand the effects of deforming walls on the haemodynamic patterns. In contrast to previous approaches, which assume rigid walls or ad hoc elastic parameters to perform the CFD simulations, wall compliance has been included in this study through the imposition of measured wall motions. This circumvents the difficulties in estimating personalized elasticity properties. Although variations in the aneurysmal haemodynamics were observed when incorporating the wall motion, the overall characteristics of the wall shear stress distribution do not seem to change considerably. Further experiments with more cases will be required to establish the clinical significance of the observed variations.

Generalized versus Patient-Specific Inflow Boundary Conditions in Computational Fluid Dynamics Simulations of Cerebral Aneurysmal Hemodynamics

“…CFD is traditionally performed by using generalized inflow boundary conditions based on typical flow rates in a healthy adult. [14][15][16][17][18][19][20][21][22][23][24][25][26][27] Recently, several studies have replaced these generalized inflow boundary conditions by patient-specific velocity measurements in the vessels proximal to the aneurysm. 10,12,[28][29][30][31][32] In these studies, either 2D phase-contrast MR imaging (PC-MR imaging) or transcranial Doppler sonography was used to measure the flow.…”

Additional Value of Intra-Aneurysmal Hemodynamics in Discriminating Ruptured versus Unruptured Intracranial Aneurysms

“…However, these assumptions are believed to have relatively limited influence on the predicted flow patterns. 28 The influence of mesh resolution is reported in an article by Valen-Sendstad and Steinman, 29 in which they have shown that lower resolution meshes can result in different oscillatory shear index values as opposed to higher resolution models. Not using the very-high-resolution models may have disguised the associations between oscillatory shear index and rupture status; however, this issue was beyond the scope of this study.…”

Fluid dynamic characterization of a novel branching anastomosis design

“…Nevertheless, the use of idealized, rigid models facilitated fundamental understanding of the effects that two different design geometries had on flow. Based on previous literature, the global flow and stress profiles generated by compliant wall simulations are similar to those from the rigid simulation case (Zhao et al 2000;Dempere-Marco et al 2006). Accordingly, rather than using our computational resources to accomplish a handful of compliant model simulations, we chose to explore a more extensive range of boundary conditions, which (such as geometry) generally have greater impact on fluid dynamic outcomes (Cebral et al 2011).…”