Work

Atherosclerotic middle cerebral artery stenosis: adjacent arterial geometry, hemodynamics and plaque features

Year: 2026

Type: article

Abstract: BACKGROUND: Adjacent vessel geometry may affect focal hemodynamics and plaque features in intracranial atherosclerotic disease. PURPOSE: To investigate the correlations of upstream (internal carotid artery (ICA) bifurcation) and focal arterial geometry of M1 middle cerebral artery (MCA-M1) with location of MCA-M1 plaques and focal hemodynamics, particularly wall shear stress (WSS) metrics. METHODS: In patients with symptomatic atherosclerotic stenosis (50-99%) of MCA-M1, we assessed vessel geometry at ICA bifurcation and MCA-M1, including diameters and diameter ratios of different arterial segments, angles between arteries, and MCA-M1 tortuosity. The MCA-M1 plaque was defined as in proximal or distal halves of MCA-M1. Computational fluid dynamics (CFD) modeling was conducted to simulate adjacent blood flow and quantify relative wall shear stress (relative WSS, rWSS) across the MCA-M1 plaque (as relative to mean WSS at proximal normal segment). We investigated the associations of vessel geometry with the plaque location and rWSS metrics. RESULTS: Among 132 patients (median age 62 years), smaller diameter of MCA-M1 origin (adjusted odds ratio = 0.19, 95%CI 0.08-0.43, p < 0.001), smaller diameter ratio of MCA-M1 origin and terminal (0.04, 0.01-0.17, p < 0.001), and larger MCA-M1 tortuosity (1.03, 1.00-1.05, p = 0.045) were associated with proximal (versus distal) MCA-M1 plaques, independent of patient characteristics. These geometric parameters were associated with higher rWSS and larger area of high-rWSS region, throughout the MCA-M1 plaque and in upstream and downstream plaque segments, in patients with proximal MCA-M1 plaques (most p < 0.05), but not in those with distal MCA-M1 plaques. CFD models also revealed different velocity profiles and flow patterns in cases with different ICA bifurcation and MCA-M1 geometry. CONCLUSIONS: Adjacent arterial geometry may affect plaque distribution in MCA-M1. Focal hemodynamics e.g., WSS and velocity profiles, may play a role underlying the associations.

Source: Japanese Journal of Radiology

DOI: 10.1007/s11604-026-02041-2