Abstract
Background: Although wall shear stress (WSS) and pressure play important roles in plaque vulnerability, characteristics of the two indices in intracranial atherosclerosis (ICAS) have not been fully investigated yet. This study aimed to elucidate this issue by means of establishing a non-invasive computational fluid dynamics method with time-of-flight magnetic resonance angiography (TOF-MRA) of the whole cerebral artery.Materials and Methods: Subjects with symptomatic ICAS in the middle cerebral artery domain were enrolled, excluding those with concomitant internal carotid artery stenosis. Based on patient-specific TOF-MRA images for three-dimensional (3D) meshes and arterial blood pressure with patient-specific carotid artery ultrasonography for inlet boundary conditions, patients' three-dimensional hemodynamics were modeled by a finite element method governed by Navier-Stokes equations.Results: Among the 55 atherosclerotic lesions analyzed by this TOF-MRA based computational fluid dynamics model, the maximum WSS (WSSmax) was most frequently detected at the apex points and the upper half of the upstream sections of the lesions, whereas the maximum pressure was most often located at the lower half of the upstream sections. As the percent stenosis increases, the relative value of WSSmax and pressure drop increased with significantly increasing steep beyond 50% stenosis. Moreover, WSSmax was found to linearly correlate with pressure drop in ICAS.Conclusions: This study on ICAS revealed certain trends of longitudinal distribution of WSS and pressure and the influences of percent stenosis on cerebral hemodynamics, as well as the correlations between WSS and pressure drop. It represents a step forward in applying computational flow simulation techniques in studying ICAS and stroke, in a patient-specific manner.
Highlights
Stroke is a leading cause of mortality, disability, and the economic costs of treatment [1]
Correlation Between WSSmax, Pressure Ratio(terminal/origin), and Pressure Drop(origin-to-terminal). By this time-of-flight magnetic resonance angiography (TOF-MRA)-based computational fluid dynamics (CFD) model, we evaluated the correlation between indices of hemodynamic forces
We proposed the potential value of routine TOFMRA-based cerebral blood flow simulation in hemodynamic assessment of intracranial atherosclerosis (ICAS)
Summary
Stroke is a leading cause of mortality, disability, and the economic costs of treatment [1]. One of the potential mechanisms is identified as the destabilizing effect by hemodynamic forces acting on plaques, generated by cerebral blood flow, the major indices of which are wall shear stress (WSS) and pressure [5]. High mechanical load generated by hemodynamic forces often reveals a hemodynamic pattern prone to plaque rupture. It is of great significance to clarify the characteristics of WSS and pressure of ICAS, in view of risk evaluation. Despite these speculations, data remain scarce by far on this issue. Wall shear stress (WSS) and pressure play important roles in plaque vulnerability, characteristics of the two indices in intracranial atherosclerosis (ICAS) have not been fully investigated yet. This study aimed to elucidate this issue by means of establishing a non-invasive computational fluid dynamics method with time-of-flight magnetic resonance angiography (TOF-MRA) of the whole cerebral artery
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