Prognostic Value of Modified Magnetic Resonance Arterial and Venous Collateral Scores in Unilateral Chronic Middle Cerebral Artery Occlusion

Objective To investigate the value of modified regional leptomeningeal collateral (rLMC) scores based on high-resolution 3D time-of-flight magnetic resonance angiography with magnetization transfer contrast (MRA-MTC-rLMC) and susceptibility-weighted angiography (SWAN-rLMC) in assessing collateral circulation and predicting clinical outcomes in patients with unilateral chronic middle cerebral artery occlusion (CMCAO). Methods In this retrospective analysis of 39 CMCAO patients, we developed enhanced rLMC scores by incorporating the posterior cerebral artery territory and deep medullary veins into traditional scoring. The resulting MRA-MTC-rLMC (10 regions, 22 points) and SWAN-rLMC (11 regions, 24 points) scores were evaluated for predicting poor outcomes (TIA, cerebral infarction, or death) using ROC curve analysis. Results Among 39 patients, 20 (51.3%) experienced poor outcomes. Both modified scores demonstrated excellent predictive performance, with AUCs of 0.938 for MRA-MTC-rLMC and 0.886 for SWAN-rLMC (both P < 0.001). The optimal cut-off of ≤ 11 for MRA-MTC-rLMC achieved 100% sensitivity and 89.5% specificity, while ≤ 12 for SWAN-rLMC showed 90% sensitivity and 89.5% specificity. Patients stratified by these cut-offs showed significant prognostic differences (P < 0.001). Conclusion The modified MRA-MTC-rLMC and SWAN-rLMC scores provide valuable assessment of collateral circulation in CMCAO. A favorable prognosis is indicated by high arterial compensation (elevated MRA-MTC-rLMC score) combined with preserved venous oxygenation (reduced SWAN-rLMC score), establishing their clinical utility for risk stratification.