In summary, PET and SPECT are versatile imaging modalities capable of providing dynamic information regarding the metabolism and physiology of brain and brain tumor. PET and SPECT are useful adjuncts to MRI and CT scanning in the important clinical areas of presurgical estimations of tumor grade. In addition, PET can be used to differentiate tumor necrosis from recurrence noninvasively, which is important for patient management. PET also may prove useful in early assessments of metabolic and physiologic changes in brain tumors following treatment and in monitoring drug delivery to tumor. Studies of drug delivery to and metabolic and physiologic responses of brain and brain tumor to treatment provide a quantitative handle on tumor response and patient prognosis. The ability to acquire such quantitative data may lead in the future to more efficient brain tumor treatment algorithms and to the development of more effective treatment protocols.