Preprocedural high-resolution vessel wall MRI predicts in-stent restenosis after intracranial stenting.

BACKGROUND: In-stent restenosis (ISR) remains a challenge after intracranial stenting for intracranial atherosclerotic stenosis (ICAS). We evaluated whether preprocedural high-resolution vessel wall imaging (HR-VWI) features and clinical factors could predict ISR. METHODS: We retrospectively analyzed 237 ICAS patients undergoing intracranial stenting with preprocedural HR-VWI and follow-up. Clinical and HR-VWI parameters were compared between ISR and non-ISR groups using the Mann-Whitney U and χ2 tests. Predictors were identified using LASSO (least absolute shrinkage and selection operator) Cox regression. A 1-year risk prediction model was constructed and visualized as a nomogram. Model performance was evaluated using C-index, calibration, decision curve analysis, and bootstrap validation. Kaplan-Meier analysis assessed ISR incidence over time. RESULTS: ISR occurred in 42 patients (17.7%) during follow-up, including 38 cases (16.0%) within 1 year. Mean normalized wall index (NWI) (per 10% increase; HR 2.37, 95% CI 1.51 to 3.73, P<0.001), plaque length (HR 1.12, 95% CI 1.03 to 1.22, P=0.010), and enhancement ratio (HR 2.27, 95% CI 1.07 to 4.82, P=0.034), along with residual stenosis (per 10% increase; HR 1.42, 95% CI 1.09 to 1.85, P=0.010), were independent predictors. The model showed good discrimination (C-index 0.79, 95% CI 0.72 to 0.86), calibration, and net benefit. Higher ISR risk was observed with mean NWI ≥0.88, plaque length ≥8 mm, enhancement ratio ≥1.07, or residual stenosis ≥39% (all P≤0.01). CONCLUSION: Preprocedural HR-VWI-derived mean NWI, plaque length, and enhancement ratio, together with residual stenosis, were associated with ISR and may aid risk stratification. Further validation in larger prospective cohorts is warranted.