Identification of vortex structures in a cohort of 204 intracranial aneurysms

Abstract

An intracranial aneurysm (IA) is a cerebrovascular pathology that can lead to death or disability if ruptured. Abnormal wall shear stress (WSS) has been associated with IA growth and rupture, but little is known about the underlying flow physics related to rupture-prone IAs. Previous studies, based on analysis of a few aneurysms or partial views of three-dimensional vortex structures, suggest that rupture is associated with complex vortical flow inside IAs. To further elucidate the relevance of vortical flow in aneurysm pathophysiology, we studied 204 patient IAs (56 ruptured and 148 unruptured). Using objective quantities to identify three-dimensional vortex structures, we investigated the characteristics associated with aneurysm rupture and if these features correlate with previously proposed WSS and morphological characteristics indicative of IA rupture. Based on the Q-criterion definition of a vortex, we quantified the degree of the aneurysmal region occupied by vortex structures using the volume vortex fraction (vVF) and the surface vortex fraction (sVF). Computational fluid dynamics simulations showed that the sVF, but not the vVF, discriminated ruptured from unruptured aneurysms. Furthermore, we found that the near-wall vortex structures co-localized with regions of inflow jet breakdown, and significantly correlated to previously proposed haemodynamic and morphologic characteristics of ruptured IAs.

A non-dimensional parameter for classification of the flow in intracranial aneurysms. II. Patient-specific geometries

“…11 To better understand the behavior of WSS, gradients of WSS, and OSI, the basic flow physics of aneurysms needs to be investigated. 1 In addition, the flow physics in aneurysms, such as flows involving complex vortical structures (high flow instabilities), 12 complex and unstable core lines, 13 or higher fraction of vortex structures near the wall, 14 can be helpful in identifying the main factors in aneurysm rupture. 12 All of the above hemodynamic parameters require simulations or experiments to be computed.…”

Shared and Distinct Rupture Discriminants of Small and Large Intracranial Aneurysms

“…15, 17, 19–21 To gain further insight into the flow dynamics of IAs, the inflow was classified as either Jet Breakdown Mode or Continuous Jet Mode. 22 We also collected and analyzed clinical features, including previous subarachnoid hemorrhage (SAH), hypertension, and IA location (Table 2).…”

Effectiveness of Stent in the Treatment of Renal Artery Aneurysm using FSI Simulation

“…Consequently, it can lead to high risk of rupture due to the disrupted flow pattern. Varble et al (2017) in their studies, found that the ruptured aneurysm had nearly 1.5 times vortex structures near the surface as compared to the unruptured aneurysm. High WSS could prompt matrix metalloproteinase production through smooth muscle cells that will result in internal elastic lamina damage and cell apoptosis (Varble et al 2017).…”

“…Varble et al (2017) in their studies, found that the ruptured aneurysm had nearly 1.5 times vortex structures near the surface as compared to the unruptured aneurysm. High WSS could prompt matrix metalloproteinase production through smooth muscle cells that will result in internal elastic lamina damage and cell apoptosis (Varble et al 2017). Du and Lü (2017) in their study regarding the growth and rupture of saccular aneurysm mentioned that WSS of around 1.5 Pa is sufficient to induce the degeneration of endothelial cells in the aneurysm wall causing formation of lesion and subsequently could lead to rupture.…”