Comparison of 1- and 2-hr delayed brain scans in patients undergoing chemotherapy for primary brain tumors

Fifty-five patients receiving various forms of chemotherapy for primary brain tumors had brain scans performed at 1 hr and again at 2 hr following injection of the radionuclide. The images were compared for changes in lesion size, lesion intensity, and surgical flap intensity. Sixteen percent (9) of the patients showed a definite increase in size of the lesions and 29% (16) a definite increase in intensity from 1-hr to the 2-hr scan. Fifty-one percent (28) of the patients showed fading in surgical flap intensity. One case of primary neoplasm, one case of meningeal spread of tumor, and one case of subdural hematoma were detected only on the 2-hr view. In addition, changes in the so-called doughnut sign were observed. These findings demonstrate a need for strict adherence to a specified time between injection and imaging in studying brain lesions receiving chemotherapy, and emphasize the superiority of the 2-hr scan for evaluation of these patients.