11C-methionine Uptake in Brain Tumors Measured by PET: Early Clinical Results

CT scan and magnetic resonance imaging are excellent for detecting brain tumors but they suffer from a number of limitations. We studied with PET the uptake of 11C-methionine in 6 patients with newly diagnosed brain tumors and in 2 patients who were suspected of tumor recurrence. They were also studied with CT and MRI. Four patients were also studied with 18FDG. Six patients were later operated, one patient underwent a biopsy while one patient had been operated of a grade IV astrocytoma three months before. The uptake of 11C-methionine was increased in each of these brain tumors, allowing a clear delineation of their extent. The tumor/controlateral cortex ratio ranged from 1.6 to 3.5 and seemed related to tumor grade. Glucose uptake was increased in 2 cases of grade IV astrocytoma and decreased in 2 grade I–II astrocytoma. 11C-methionine might be a more interesting tracer for imaging brain tumors than 18FDG and appears useful for the evaluation of tumor activity.