PET versus SPECT in distinguishing radiation necrosis from tumor recurrence in the brain.

Two cases of postsurgical brain tumor evaluation in which MRI was inconclusive are discussed. Functional imaging techniques, such as FDG-PET and 201TI SPECT, were used in both cases for distinguishing radiation necrosis from tumor recurrence. These methods proved to be complimentary. For Patient 1, FDG-PET showed more limitations compared to 201TI SPECT. FDG-PET results on the other hand, were consistent with the final diagnosis and the SPECT image was false positive for tumor recurrence in Patient 2.