11C-methionine and 18F-2-fluorodeoxy-glucose positron emission tomography:: A tool for diagnosis of cerebral glioma and monitoring after brachytherapy with 125I seeds

Forty-six patients with suspected brain tumors were investigated by positron emission tomography (PET). Using C-11-methionine PET, the spatial extent of increased uptake in gliomas was larger than that of contrast enhancement on CT/MR images in 67% or the same in 33%. Ten of 46 patients treated with brachytherapy for low-grade gliomas were also investigated with F-18-2-fluorodeoxyglucose (FDG)-PET. One year after seed implantation, the glucose metabolism had not changed, but the decline of methionine uptake was significant. In conclusion, C-11-methionine PET may improve tumor delineation and, following brachytherapy, provides more information on the therapeutic effects than FDG.