[Brain necrosis following intraoperative radiation therapy or interstitial brachytherapy]

We have experienced 8 cases of radiation necrosis which occurred following radiation therapy of malignant brain tumors. In all 8 cases, necrosis developed in the brain tissue adjacent to the tumor after intraoperative radiation or interstitial radiation therapy. Considering that the extent of necrosis usually coincides with the extent of the radiation therapy, this type of necrosis is thought to be the expected result of radiation therapy. A differential diagnosis between radiation necrosis and the recurrence of a brain tumor has been thought to be difficult to achieve. Yet with the use of a dynamic CT or an Xe-enhanced CT, differential diagnosis between these two lesions was clearly accomplished.