Brain scans, dexamethasone therapy, and brain tumors.

Eight men with primary or metastatic brain tumors were examined with brain scans before and after the administration of dexamethasone. All patients demonstrated some improvement in their clinical neurologic status during therapy, and two patients had a dramatic response. Seven of the eight patients examined showed a decrease in the apparent size of the original lesion on recent brain scan while receiving dexamethasone. Comparison of immediate scans obtained 15 to 20 minutes following the administration of sodium pertechnetate Tc 99m with those obtained two or three hours later suggests that the change in apparent size of the original lesion results from decrease in peritumor edema.