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 may serve as potentially effective, yet preliminary, imaging tools for assessing 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.