ABSTRACT NUMBER: ESOC2026A811 OVERESTIMATION OF LUMINAL STENOSIS BY TOF-MRA OVER CTA INDICATES HEMODYNAMIC IMPAIRMENT AND PREDICTS STROKE RECURRENCE IN SYMPTOMATIC INTRACRANIAL ATHEROSCLEROTIC STENOSIS

Abstract Background and aims Time-of-flight magnetic resonance angiography (TOF-MRA) can overestimate the severity of luminal stenosis in intracranial atherosclerotic stenosis (ICAS), which may indicate hemodynamic impairment. We investigated whether such overestimation predicted stroke recurrence in symptomatic ICAS (sICAS). Methods Patients with 50-99% sICAS, confirmed by CT angiography (CTA), with TOF-MRA exam within one month, were enrolled from 2 hospitals. Stenosis severity of sICAS was assessed in CTA and TOF-MRA, and patients were grouped into 3 groups: 1) CTA-MRA moderate stenosis (50-69% stenosis by both); 2) CTA-MRA mismatch (50-69% stenosis in CTA, 70-99% stenosis or focal flow gap in TOF-MRA); and 3) CTA-MRA severe stenosis group (severe stenosis by both). Computational fluid dynamics (CFD) models were constructed based on CTA to quantify translesional pressure ratio (PR) in sICAS. The primary outcome was same-territory ischemic stroke or TIA within 1 year. Results Among 218 patients (median age 61 years), 92 (42.2%), 66 (30.3%), and 60 (27.5%) were respectively classified into CTA-MRA moderate stenosis, mismatch and severe stenosis groups. Primary outcome occurred in 31 (14.2%) patients. In multivariate Cox regression, compared to CTA-MRA moderate stenosis, both CTA-MRA mismatch (adjusted HR=2.75, p=0.044) and CTA-MRA severe stenosis (adjusted HR=4.30, p=0.006) groups had significantly higher risks of primary outcome. Among 90 patients with CFD modeling, sICAS lesions in CTA-MRA mismatch and severe stenosis groups were hemodynamically more severe than CTA-MRA moderate stenosis group (median PR 0.91, 0.83 vs. 0.98, p<0.001). Conclusions Overestimation of the stenosis severity by TOF-MRA over CTA may identify sICAS with hemodynamic significance and higher risk of stroke/TIA recurrence. Conflict of interest nothing to disclose