Dual time point 18F-FDOPA PET as a tool for characterizing brain tumors

¹⁸F-FDOPA is an amino acid analogue used to evaluate presynaptic dopaminergic activity, which has aroused great interest in neuro-oncology. We have evaluated five ¹⁸F-FDOPA PET studies of patients referred for study of parkinsonian syndrome. Two subjects had previously treated high- grade brain tumors, one nonspecific brain injury, and 2 subjects presented unexpected tumoral lesions. For all lesions SUVmax, time to SUVmax and tumor-to-normal grey matter SUVmax rate (T/N) were calculated, and 90 minutes ¹⁸F-FDOPA kinetics were analyzed. Tumor lesions corresponded to three malignant neurocytomas, one meningioma, one pineocytoma and one intrasinusal heman- gioma. Both malignant and benign tumors exhibited high uptake of ¹⁸F-FDOPA well above the normal cortex. However, the analysis of the curve uptake displayed characteristic patterns that facilitate the characterization of tumor lesions. A dual phase maximum uptake was observed, with an early 10 minutes uptake in malignant lesions, and a late 60 to 90 minutes uptake in benign or low grade lesions.