Evaluation of Early Computed Tomographic Findings in Acute Ischemic Stroke

Abstract

Background and Purpose —Detection of large, hypoattenuated brain-tissue volume on hyperacute CT scan has been suggested as an exclusion criterion for early intravenous tissue plasminogen activator (IV-tPA) treatment. This study assessed the reliability of detection for these findings and their relationship to outcome. Methods —Fifty hyperacute CT scans (<6 hours after ictus) were selected from a randomized trial evaluating IV-tPA (ATLANTIS trial). Three neuroradiologists blinded to all clinical information evaluated scans for degree of MCA territory involvement (<33% or >33%) and the presence of a hyperdense MCA. Evaluations were compared with 24-hour scan results, 30-day infarct volumes, and baseline NIH stroke scale scores (NIHSS). Results —Readers reliably evaluated the degree of MCA territory hypodensity (intraclass correlation=0.53, P <0.001), with all 3 readers agreeing in 36 of 50 cases (72%). They correctly called >33% involvement with a sensitivity of 60% to 85% and a specificity of 86% to 97%. The baseline NIHSS was higher when >33% MCA hypodensity was seen ( P =0.021). Detection of significant hypodensity (>33%) correlated with poorer outcome. When >33% hypodensity was not detected, mean 30-day infarct volumes were 27.0 to 33.0 cm 3 , versus 84.3 to 123.1 cm 3 when >33% hypodensity was present ( P =0.002). Conclusions —Detection of MCA territory hypodensity on hyperacute CT scans is a sensitive, prognostic, and reliable indicator of the amount of MCA territory undergoing infarction.