Functional assessment of cerebral artery stenosis: A pilot study based on computational fluid dynamics

Abstract

The fractional pressure ratio is introduced to quantitatively assess the hemodynamic significance of severe intracranial stenosis. A computational fluid dynamics-based method is proposed to non-invasively compute the FPR and compared against fractional pressure ratio measured by an invasive technique. Eleven patients with severe intracranial stenosis considered for endovascular intervention were recruited and an invasive procedure was performed to measure the distal and the aortic pressure ( P and P). The fractional pressure ratio was calculated as [Formula: see text]. The computed tomography angiography was used to reconstruct three-dimensional (3D) arteries for each patient. Cerebral hemodynamics was then computed for the arteries using a mathematical model governed by Navier-Stokes equations and with the outflow conditions imposed by a model of distal resistance and compliance. The non-invasive [Formula: see text], [Formula: see text], and FPR were then obtained from the computational fluid dynamics calculation using a 16-core parallel computer. The invasive and non-invasive parameters were tested by statistical analysis. For this group of patients, the computational fluid dynamics method achieved comparable results with the invasive measurements. The fractional pressure ratio and FPR are very close and highly correlated, but not linearly proportional, with the percentage of stenosis. The proposed computational fluid dynamics method can potentially be useful in assessing the functional alteration of cerebral stenosis.

Characteristics of Wall Shear Stress and Pressure of Intracranial Atherosclerosis Analyzed by a Computational Fluid Dynamics Model: A Pilot Study

“…It is worth noting that the index of pressure ratio (terminal/origin) in our study was similar to the recently proposed index of fractional pressure ratio by Liu et al, who have demonstrated that for symptomatic ICAS, it was a good approximation of fractional flow reserve, the gold standard for assessing the physiological significance of coronary stenotic lesions (8,23). Moreover, one recent study has demonstrated the close correlation between translesional pressure ratio, translesional WSS ratio, and stroke…”

“…The 3D geometric model was then reconstructed by a suite of software, Mimics (Materialize NV, Belgium), and then examined and manually revised by two neurologists, with the primary collaterals included. Further processing of the vascular surface and generation of the computational domain (volume mesh) was performed using the ANSYS ICEM CFD meshing software (ANSYS, Inc., USA) (6)(7)(8).…”

“…We then applied an instantaneous pulsatile inflow and incorporated a lumped parameter model to mimic the downstream effects from the distal vessels on the outlet boundaries. The detailed calculation of the outlet condition was performed by the same method reported previously (8). The governing equations of blood flow were described by 3D steady incompressible Navier-Stokes equations.…”

“…Several studies have applied computational fluid dynamics (CFD) to simulate and analyze the hemodynamics of ICAS (6)(7)(8). However, these studies relied on images of computed tomography angiography, which causes concerns in radioactivity and contrast administration, and applied with the hypothetical inlet flow condition.…”

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

“…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.…”