Hemodynamics and plaque distribution in basilar artery fenestration: Computational fluid dynamics and high-resolution...

High-resolution MRI (HRMRI) has emerged as a critical tool for intracranial arterial wall imaging, enabling direct visualization of atherosclerotic plaque morphology and distribution with superior spatial resolution. Basilar artery fenestration (BAF), a congenital vascular variant, presents unique. Med Phys. 2026;00:00-00. https://doi.org/10.1002/mp.70349 hemodynamic conditions that may drive localized plaque formation. The combination of HRMRI and computational fluid dynamics (CFD) provides a powerful physics-based approach to investigate the biomechanical determinants of atherosclerosis in this specialized anatomy.

To characterize plaque distribution patterns in BAF patients via HRMRI and elucidate their hemodynamic correlates through CFD, focusing on wall shear stress (WSS) modulation induced by fenestration morphology.

HRMRI datasets from 26 BAF patients (July 2014-June 2021) were retrospectively analyzed. Plaque characteristics (location, thickness) were systematically evaluated by two blinded neuroradiologists using three-dimensional volumetric isotropic turbo spin-echo acquisition (3D VISTA) images. Patient-specific CFD models were reconstructed to assess local blood flow, WSS, and oscillatory shear index (OSI).

HRMRI revealed distinct spatial patterning of atherosclerotic plaques in BAF patients. Fifteen plaques were detected in 11/26 patients, with 8 located in the fenestration segment, 7 in the downstream segment. In the fenestration segment, 50.0% (4/8) of plaques localized to lateral walls, surpassing ventral (25.0%, 2/8), dorsal (25.0%, 2/8), and interior walls (0). This lateral predominance persisted downstream (71.4%, 5/7 plaques). CFD analysis revealed significantly lower WSS on the lateral walls of the fenestration branches compared to other regions (left branch: lateral vs. medial, P = 0.0031; right branch: lateral vs. ventral and dorsal, P = 0.0319 and 0.0408). In the downstream segment, however, WSS differences among the four quadrant walls were not statistically significant. Furthermore, notable differences in WSS were observed between the BAF model and the idealized control model.

BAF morphology creates localized low-WSS microenvironments at fenestration lateral walls, correlating spatially with plaque predilection. These findings highlight the utility of CFD-HRMRI integration in decoding vascular biomechanics and suggest WSS mapping as a potential biomarker for atherosclerosis risk stratification in anatomical variants. The diminishing hemodynamic influence downstream implicates native vascular geometry as a co-determinant of plaque distribution, warranting further multiscale modeling studies.