INVIVO IMAGING OF VESICULAR MONOAMINE TRANSPORTERS IN HUMAN BRAIN USING [C-11] TETRABENAZINE AND POSITRON EMISSION TOMOGRAPHY

The pharmacokinetics of [C-11]tetrabenazine, a high-affinity radioliga nd for the monoamine vesicular transporter, were determined in living human brain using in vivo imaging by positron emission tomography (PET ). The radiotracer showed high brain uptake and rapid washout from all brain regions with relatively slower clearance from regions of highes t concentrations of monoamine vesicular transporters (striatum), resul ting in clear differential visualization of these structures at short intervals after injection (10-20 min). As the first human PET imaging study of a vesicular neurotransmitter transporter, these experiments d emonstrate that external imaging of vesicular transporters forms a new and valuable approach to the in vivo quantification of monoaminergic neurons, with potential application to the in vivo study of neurodegen erative disorders such as Parkinson's disease.