Correlation of clot imaging with endovascular recanalization in internal carotid artery terminus occlusion

Background and purpose In a swine stroke model we have previously demonstrated a high-intensity fluid attenuated inversion recovery (FLAIR) signal representing the erythrocyte component of the clot. We hypothesized that the intensity of the FLAIR clot signal in patients with acute stroke may predict the efficacy of recanalization by thrombectomy devices. In this study we compared the pretreatment FLAIR signal intensity of the clots in the distal internal carotid artery (ICA) and the degree of angiographic recanalization rate after mechanical thrombectomy. Methods 25 consecutive acute stroke patients with ICA terminus (ICA-T) occlusion diagnosed with MRI at the UCLA Medical Center between 2002 and 2013 were retrospectively reviewed. The intensity of the FLAIR clot signal at the distal ICA was blindly compared with the angiographic recanalization status (successful recanalization defined as Thrombolysis In Cerebral Infarction (TICI) score of 2b-3) and non-successful recanalization as TICI score 0-2a) after endovascular treatment. Multivariate logistic regression analysis for successful recanalization was performed. Results Successful recanalization was achieved in 40% of patients (10/25) and showed a significantly higher FLAIR intensity (p=0.014). The cut-off value for clot intensity on the FLAIR sequence to predict recanalization was 0.7952, with 70% sensitivity and 80% specificity (95% CI 0.59 to 0.96) using a receiver operating characteristic curve. In multivariate logistic regression analysis, only a high FLAIR clot intensity (>0.7952) was associated with successful recanalization (OR 16.79; 95% CI 1.29 to 218.92; p=0.031). Conclusions High signal intensity on FLAIR clot imaging may predict successful recanalization after endovascular therapy for ICA-T occlusion.