The intensity of parenchymal brain lesions was compared using Tc-99m pertechnetate and Tc-99m phosphate. The following conclusions were made: 1. If the Tc-99m phosphate intensity is greater than the intensity of the Tc-99m pertechnetate scan, and the patient is evaluated within four weeks of ictus, the lesion is a CVA (P less than .001). 2. If the Tc-99m phosphate intensity is less than or equal to the intensity of the Tc-99m pertechnetate scan, and the patient is evaluated within four weeks of ictus, the parenchymal lesion is not a CVA (P less than .001). 3. If the evaluation takes place longer than six weeks after ictus, then no evaluation about the nature of the lesion can be made based upon uptake of Tc-99m phosphate and Tc-99m pertechnetate.