A SIMPLE PRACTICAL CLASSIFICATION OF CEREBRAL INFARCTS ON CT AND ITS INTEROBSERVER RELIABILITY

PURPOSE: To test the interobserver reliability of a simple method of c lassifying cerebral infarcts as seen on CT brain scans, which might al low differentiation of the site and size of the infarct from infarct s welling and hemorrhagic transformation. METHOD: Two experienced neuror adiologists independently reviewed 119 CT brain scans showing recent s mall to large cortical and subcortical cerebral infarcts and classifie d each for site and size, amount of swelling, and hemorrhagic transfor mation blind to clinical information. Six less experienced general rad iologists in training classified 33 of the CT scans blind to clinical information. Interobserver agreement was calculated using unweighted k appa statistics. RESULTS: The kappa statistics between the two experie nced neuroradiologists were: (a) 0.78 for site and size (95% confidenc e interval, 0.69-0.87); (b) 0.8 for swelling (95% confidence interval, 0.68-0.92); and (c) 0.3 for hemorrhagic transformation (95% confidenc e interval, 0-0.77); indicating ''good,'' ''excellent,'' and ''fair'' agreement, respectively. Agreement for the less experienced radiologis ts was fair to excellent. CONCLUSION: The cerebral infarct morphologic classification is simple, quick, and reliable and therefore practical . It usefully distinguishes between infarcts of similar site and size but with different amounts of swelling and hemorrhagic transformation, thus facilitating study of factors such as the influence of drug trea tment on infarct swelling, which might influence clinical outcome. Alt hough developed for CT, it could be used equally for MR imaging and ha s applications in research and clinical practice.