Radiation-induced medulloblastoma in an adult: A functional imaging study

C-Met and 11 C-Choline PET 11 C-methionine ( 11 C-Met), 11 C-Choline, and Magnetic Resonance Spectroscopy (MRS). The co-registered MRI and FDG images of the brain demonstrated very minimal to absent glucose uptake in the contrast-enhancing lesion in the poste- rior fossa. This observation was not suggestive of a high-grade tumor but rather radiation necrosis. The 11 C-Met PET study demonstrated areas of increased methionine uptake greater than the cortex in an area corresponding to the contrast-enhancing abnormality noted on the MRI scan. The findings on 11 C-Met PET were more suggestive of a tumor, but nevertheless did not exclude the presence of radiation necrosis. 11 C-choline PET study suggested the presence of a tumor with prominent 11 C-choline uptake, in the region of the contrast-enhanc-