What does computational fluid dynamics tell us about intracranial aneurysms? A meta-analysis and critical review

Abstract

Despite the plethora of published studies on intracranial aneurysms (IAs) hemodynamic using computational fluid dynamics (CFD), limited progress has been made towards understanding the complex physics and biology underlying IA pathophysiology. Guided by 1733 published papers, we review and discuss the contemporary IA hemodynamics paradigm established through two decades of IA CFD simulations. We have traced the historical origins of simplified CFD models which impede the progress of comprehending IA pathology. We also delve into the debate concerning the Newtonian fluid assumption used to represent blood flow computationally. We evidently demonstrate that the Newtonian assumption, used in almost 90% of studies, might be insufficient to describe IA hemodynamics. In addition, some fundamental properties of the Navier–Stokes equation are revisited in supplementary material to highlight some widely spread misconceptions regarding wall shear stress (WSS) and its derivatives. Conclusively, our study draws a roadmap for next-generation IA CFD models to help researchers investigate the pathophysiology of IAs.

The hemodynamic complexities underlying transient ischemic attacks in early-stage Moyamoya disease: an exploratory CFD study

“…Indeed, we do not argue that hemodynamic studies of the CBF such as MR-SPECT should have a lesser importance, on the contrary, we employed these techniques as the gold standard for clinical diagnosis. Our aim was to take the CFD a step further towards its ultimate clinical goal as a clinical diagnostic and decision-making tool 12 . In this work we clearly demonstrate the power of CFD as decision making tool, even though the study was performed retrospectively, as CFD analysis was able to predict the root causes of hemodynamic insufficiency in our patient cohort, and to demonstrate why they did not respond to medical therapy.…”

“…We have recently shown that the Newtonian assumption used in CFD models of cerebral blood flow is an inappropriate over-relaxed assumption 12,59 . To model the non-Newtonian shear thinning blood properties, the Carreau-Yasuda 60 model was used.…”

“…To address this critical issue, we investigated the hemodynamic complexities of early-stage MMD by analyzing five MMD patients presenting with progressive ischemia despite their mild or moderate stenosis of the affected arteries using high-fidelity computational fluid dynamics (CFD) simulations. We hypothesized that studying hemodynamic phenomena could provide valuable information to delineate the underlying pathology and symptomatology of early-stage MMD since CFD has been a valuable tool that provided critical information to evaluate the relationship between the pathobiology of the vascular wall anatomy and the blood hemodynamics in variety of cerebrovascular diseases 12 .…”

“…Several vascular diseases had their hemodynamic features studied using computational fluid dynamics (CFD) to understand the relationship between the pathobiology of endothelial cells and the vessel wall and blood hemodynamics and physics 12 . There is a wealth of publications for example on cerebral aneurysms, carotid stenosis and intracranial stenosis [12][13][14][15][16][17] . However, a Scopus search using the terms; "Moyamoya" + "computational fluid dynamics" or "CFD" reveals less than 10 publications that explored the blood dynamics features associated with MMD but with no possible link to early MMD pathology or symptomatology.…”

Using hemodynamic parameters quantified with computational fluid dynamics to explore potential mechanisms of occurrence and progression in Alzheimer Disease

“…CFD technique can reduce unnecessary interventional angiography effectively and help doctors to diagnose pathological conditions [22,23] . Moreover, CFD can be applied to assess the risk of rupture and pressure of the intracranial aneurysm, thereby improving the understanding of the biomechanics of the aneurysms [24] .…”