Distance to Thrombus in Acute Middle Cerebral Artery Occlusion Predicts Target Mismatch and Ischemic Penumbra.

BACKGROUND AND PURPOSE: In patients with occlusion of the middle cerebral artery (MCA) treated by intravenous thrombolysis (IVT), the distance to thrombus (DT) has been proposed as a predictor of outcome. The purpose of the present study was to investigate how DT relates to dynamic susceptibility contrast perfusion metrics. METHODS: Retrospective analysis was undertaken of patients who were diagnosed with acute MCA occlusion by magnetic resonance imaging and treated with IVT. Volumes of time-to-maximum (Tmax) perfusion deficits and diffusion-weighted imaging (DWI) lesions, diffusion-perfusion mismatch volumes, and the presence of target mismatch were determined. Correlations between the above stoke measures and DT were then calculated. RESULTS: Fifty-five patients were included. DT showed significant inverse correlations with Tmax greater than 4, 6, 8, and 10 seconds, respectively, and mismatch volumes. Using the DT group median (14 mm) as a separator, significant intergroup differences were observed for Tmax greater than 4, 6, and 8 seconds, respectively, and for mismatch volumes. Grouping DT into quartiles showed significant intergroup differences regarding mismatch volumes and Tmax values greater than 4 and 6 seconds. Binary logistic regression identified DT (odds ratio [OR] = .89; 95% confidence interval [CI], .81-.99) and DWI lesion volumes (OR = .92; 95% CI, .86-.97) as independent predictors of target mismatch. A low DT predicted target mismatch with an area under the curve of .69. CONCLUSIONS: DT correlates inversely with Tmax perfusion deficits and mismatch volumes and acts as an independent predictor of target mismatch.