Efficacy of collateral circulation analysis by single-phase CT angiography for acute large vessel occlusion

Abstract

Background and Purpose: Collateral circulation is known to influence the outcomes of mechanical thrombectomy for acute large vessel occlusion, but the assessment method has not been established. We explored the efficacy of collateral circulation assessment using simple single-phase CT angiography (CTA). Methods: From June 2015 to November 2019, we retrospectively studied 51 patients who underwent thrombectomy for ICA or MCA M1 segment occlusion. We compared the contrast-enhanced area of the occluded vessel territory on single-phase CTA to the contralateral side (collateral score 0, 0%; 1, 1–50%; 2, 51–99%; 3, 100%). The 90-day outcomes were classified as favorable for mRS grade 0–2. Results: 20 patients had favorable outcomes. No significant differences were observed between the favorable and unfavorable outcome groups in the reperfusion status and the time from onset to reperfusion. The only factor related to the outcomes was the development of collateral circulation (p=0.012). A higher collateral score was significantly associated with a higher proportion of favorable outcomes (p<0.001). Conclusion: Collateral score from single-phase CTA can easily predict the clinical outcomes of patients treated with mechanical thrombectomy, making it a convenient tool for assessing treatment indications.