Striatal Distribution of Dopamine Transporters and Dopamine D2 Receptors at Different Stages of Parkinson's Disease A CFT and RAC PET Study

We investigated the alteration of dopaminergic system in striata of Parkinson's disease (PD) at different stages using positron emission tomography (PET), [11C]2β-carbomethoxy-3β-(4-fluorophenyl)tropane (CFT) for dopamine transporter (DAT), and [11C]raclopride (RAC) for dopamine D2 receptor (D2R). We studied eight elderly healthy volunteers (Group A), 13 drug naive patients with PD (Group B), and seven advanced PD patients with mild dyskinesia (Group D). Six patients in Group B were re-examined after antiparkinsonian therapy (Group C). Regions of interest were drawn on the cerebellar hemisphere, head of the caudate nucleus (CN), and anterior (AP) and posterior putamen (PP) in the PET images. We calculated uptake ratio index (URI), asymmetry index (AI) and presynapse-to-postsynapse ratio (PPR) to evaluate dopaminergic function. DAT was smaller in the three PD groups than the Group A. URI of RAC in the PP was significantly larger in Group B than in Groups A and C. AI of CFT in the putamen was larger in the ...