Comparative Evaluation of F-18 FDOPA, F-18 FDG, and F-18 FLT-PET/CT for Metabolic Imaging of Low Grade Gliomas

Abstract

We undertook this prospective study to compare amino acid metabolism, glucose metabolism, and proliferation in primary and recurrent low grade gliomas using positron emission tomography (PET)/computed tomography with F-18 FDOPA, F-18 FDG, and F-18 FLT. Fifteen patients with newly diagnosed or previously treated low grade gliomas (WHO grade I or II) were subjected to F-18-FDOPA, F-18 FDG, and F-18 FLT PET/computed tomography studies on consecutive days. This included 2 patients in remission as control subjects. Uptake of all the 3 tracers were analyzed visually and quantified using standardized uptake values and tumor to normal (T/N) ratios. The accuracy of all the 3 PET tracers in the detection of newly diagnosed and recurrent low grade gliomas was compared. F-18 FDOPA was positive in all cases of primary and recurrent low grade gliomas and negative in the patients in remission. Tumor was visualized on F-18 FDG in 7 of 13 cases, F-18-FLT was positive in 4 of 13 cases. Average tumor standardized uptake values max for F-18 FDOPA (5.75 +/- 4.9) and F-18 FLT (1.8 +/- 0.91) was lower than that of F-18 FDG (8.5 +/- 4.4). T/N ratios for F-18-FDOPA (2.3 +/- 0.51) and F-18 FLT (1.8 +/- 0.91) were higher than F-18 FDG (1.03 +/- 0.64) providing good image contrast for tumor detection in positive cases. F-18 FDOPA scan is superior to both F-18 FLT and F-18 FDG for visualization of primary and recurrent low grade gliomas. F-18-FLT should not be considered for evaluation of recurrent low grade gliomas.