Measurement of Infarct Size Using MRI Predicts Prognosis in Middle Cerebral Artery Infarction

Abstract

Background and Purpose An accurate measure of the severity of ischemic insult and the resulting prognosis is needed to assess the effectiveness of new treatments for acute stroke. We studied the reproducibility and accuracy of measurements of infarct volume with MRI and correlated the measurements with outcome. Methods Infarct volume was measured on T 2 -weighted images with the A nalyze image analysis software. This technique was found to be highly accurate and reproducible. Results Measurements of infarct volume were found to be highly accurate and reproducible. Twenty-one patients (mean age, 66.5 years; range, 28 to 90 years) with cortical middle cerebral artery territory infarcts in whom adequate data could be obtained were studied within 72 hours from onset (mean delay to MRI, 27.5 hours; range, 5 to 72 hours). The Scandinavian Stroke Scale was used to calculate a prognostic score, and clinical outcome was assessed at 3 months. Infarct volume was found to significantly predict outcome. Mean infarct volume in the independent patients was 35.7±29.7 cm 3 compared with 88.3±71.3 cm 3 in dependent patients and 166.5±65.9 cm 3 in dead patients (F=10.52, P <.001). Patients with an initial infarct volume less than 80 cm 3 were found to have a better outcome than those with larger infarct volumes. Secondary hemorrhage visible on MRI also predicted a poor outcome. In contrast, the Scandinavian Stroke Scale did not significantly predict outcome. Conclusions The results demonstrate that measurement of the size of middle cerebral artery infarction with MRI is a useful tool in assessing prognosis and will have a valuable role in assessing new therapeutic agents.