CLINICAL-VALUE OF PET WITH F-18 FLUORODEOXYGLUCOSE AND L-METHYL-C-11-METHIONINE FOR DIAGNOSIS OF RECURRENT BRAIN-TUMOR AND RADIATION-INJURY

We studied 15 patients clinically suspected to have recurrent brain tumor or radiation injury, using positron emission tomography (PET) with F-18-fluorodeoxyglucose ((FDG)-F-18) and L-methyl-C-11-methionine (C-11-Met). PET with C-11-Met (Met-PET) clearly delineated the extent of recurrent brain tumor as focal areas of increased accumulation of C-11-Met, and was useful for early detection of recurrent brain tumor. PET with (FDG)-F-18 (FDG-PET) showed focal (FDG)-F-18-hypermetabolism in one patient with malignant transformation of low grade glioma, and demonstrated its usefulness for evaluation of malignant transformation. (FDG)-F-18-hypometabolism was observed in all patients with radiation injury, but was also found in one patient with recurrent malignant brain tumor. C-11-Met uptake in 3 patients with radiation injury was similar to that of the normal cortical tissue. FDG-PET can be used to initially exclude recurrent brain tumor which is seen as (FDG)-F-18-hypermetabolism. The combined use of Met-PET in addition to FDG-PET can improve the accuracyof differentiation of recurrent brain tumor with (FDG)-F-18-hypometabolism from radiation injury.