Four-dimensional CT angiography-derived dynamic collaterals and perfusion deficits as predictors of stroke recurrence in moderate middle cerebral artery stenosis: A prospective cohort study

Background Non-cardioembolic non-disabling minor ischemic stroke carries a considerable risk of early recurrence that is not fully captured by clinical severity scales. Hemodynamic impairment and collateral status may improve risk stratification. Purpose To assess the prognostic value of four-dimensional computed tomography angiography (4D-CTA)-derived collateral status and CT perfusion parameters for predicting recurrence in patients with minor stroke and moderate middle cerebral artery (MCA) stenosis. Material and Methods In this prospective study (July 2024 to June 2025), 183 patients with minor ischemic stroke (National Institutes of Health Stroke Scale (NIHSS) ≤ 5) and symptomatic moderate (50%–69%) MCA stenosis were enrolled. All underwent multimodal CT imaging and received standardized dual antiplatelet therapy. Collateral status was graded using 4D-CTA (modified American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR)), and perfusion parameters, including relative cerebral blood flow (rCBF) and Tmax, were quantified. The primary endpoint was recurrent ischemic stroke or transient ischemic attack. Cox regression and subgroup analyses were performed. Results Over a median follow-up of approximately 10 months, rCBF < 30% volume was the only independent predictor of recurrence (hazard ratio (HR) = 1.168, 95% confidence interval (CI) 1.039–1.314; P = 0.010). Poor collateral status showed a non-significant trend overall (HR = 2.079; P = 0.093) but was strongly associated with recurrence in patients without limb weakness (HR = 9.875; P = 0.030). Conclusion Multimodal CT-derived hemodynamic parameters outperform clinical scores in predicting recurrence. rCBF <30% is a robust predictor, while 4D-CTA collateral assessment is particularly valuable in clinically mild patients without motor deficits.