EXPRESS: Diagnostic and prognostic value of on-site CT-derived fractional flow reserve in intracranial atherosclerotic stenosis

BACKGROUND: The role of CT-derived fractional flow reserve (CT-FFR) in cerebrovascular disease remains undefined. This study validated the diagnostic and prognostic value of an on-site CT-FFR in symptomatic intracranial atherosclerotic stenosis (sICAS) patients. METHODS: This retrospective study enrolled sICAS patients with 30 - 99% stenosis confirmed by CTA, divided into two substudies. The diagnostic performance study included 259 patients undergoing CTA and CT perfusion (CTP) or four-dimensional CTA (CTP as reference standard). In prognosis study, 452 patients with at least 1-year follow-up were included. Computational fluid dynamics (CFD) model was used to measure CT-FFR. Diagnostic performance was assessed by receiver-operating characteristic (ROC) curves, and predictive value by Cox regression analysis. RESULTS: The diagnostic performance of CT-FFR was significantly higher than diameter stenosis (DS) on both per-patient (P = 0.009) and per-lesion (P = 0.004) basis. And the cut-off value of CT-FFR diagnosing cerebral hypoperfusion was 0.80. 15.0% (68 / 452) patients experienced recurrent ischemic events during the median 24 (17-33) months follow-up. CT-FFR provided incremental prognostic value beyond traditional cardiovascular risks plus DS (AUC = 0.797 vs 0.716, P < 0.001). CONCLUSION: This on-site CT-FFR can serve as a valuable tool for diagnosis and risk stratification in sICAS patients.