Contributions of nuclear medicine to the diagnosis of recurrent cerebral tumors and cerebral radionecrosis

The evaluation of brain tumor recurrence and therapy-induced benign changes following surgery and/or irradiation is a diagnostic challenge for imaging methods based on either morphology (cCT/MRI) or function (SPECT/PET). Curr ent literature and the present data of our own patients demonstrate the dia gnostic efficiency of IMT-SPECT and FDG-PET in the detection of recurrence and in-vivo grading. Thirty-nine patients suspected of brain tumor recurren ce at follow-up were studied by FDG-PET and IMT-SPECT. Thirty-four of 39 pa tients showed recurrences; in 12 cases even a change in the grade of malign ancy was observed. All high-grade recurrences could be confirmed by either methods. IMT-SPECT showed a higher sensitivity in detecting low-grade tumor s at recurrence. In contrast to IMT-SPECT, FDG-PET supports sufficient in-v ivo grading. Both methods can be used to differentiate between tumor recurr ence and radionecrosis. In conclusion the results of our study demonstrate the efficiency of IMT-SPECT and FDG-PET in confirming recurrences and deter mining the actual tumor grade.