Principles and application of PET in brain tumors

From the introduction of PET as an imaging modality, radiotracers such as FDG and CMET have been extensively studied and in some situations may provide complementary information to traditional MR imaging sequences with regard to tumor delineation and distinguishing necrosis from tumor recurrence. Nevertheless, FDG is limited by high background activity in the remainder of the brain and CMET is essentially limited to institutions with on-site cyclotron and nuclear chemistry facilities. However, newer radiotracers continue to be developed that offer the potential of being accessible as well as providing complementary information for diagnosis and tumor delineation. This may prove to be of use when planning surgery or radiation treatments, or when trying to differentiate pseudoresponse or pseudoprogression from tumor, a problem that is becoming increasingly frequent with newer therapeutic strategies in the management of gliomas. Radiotracers such as FDOPA and FET that are taken up preferentially by tumors independent of the integrity of the BBB seem to show particular promise, but further prognostic studies evaluating their clinical utility are warranted.