In Vivo Measurement of Vesicular Monoamine Transporter Type 2 Density in Parkinson Disease with 18F-AV-133

PET provides a noninvasive means to evaluate the functional integrity of the presynaptic monoaminergic system in the living human brain. Methods: In this study, a novel F-18-labeled tetrabenazine derivative, F-18-(1) fluoropropyldihydrotetrabenazine (F-18-AV-133), was used for the noninvasive assessment of the vesicular monoamine transporters type 2 (VMAT2) in 17 Parkinson disease (PD) patients and 6 healthy controls. The binding potential (BP) of F-18-AV-133 was calculated using Logan graphical analysis. Voxel-based and volume-of-interest-based analyses of BP images were performed to examine brain regional reductions in VMAT2 density in PD. Results: VMAT2 BP was decreased by 81% in the posterior putamen, 70% in the anterior putamen, and 48% in the caudate nucleus of PD patients. Voxel-based analysis demonstrated VMAT2 reductions in the striatum and mid brain of PD patients. Furthermore, VMAT2 BPs in the caudate nuclei significantly correlated with the clinical severity of PD. Conclusion: These findings indicate that the novel F-18-labeled ligand F-18-AV-133 can sensitively detect monoaminergic terminal reductions in PD patients. Studies with F-18-AV-133 may allow the presymptomatic identification of individuals with disorders characterized by degeneration of dopaminergic nigrostriatal afferents.