Regional imbalance of striatal dopaminergic function in Parkinson's disease visualized with 11C-CFT and 11C-raclopride PET

Abstract

The aim of this study was to investigate regional correlation between pre- and post-synaptic dopaminergic functions in the striatum of Parkinson's disease (PD). Ten PD patients (HY score I–III) underwent two positron emission tomography (PET) studies with 11C-CFT for dopamine reuptake sites as a marker of pre-synaptic dopaminergic function and with 11C-raclopride (RAC) for dopamine D 2 receptors as a marker of post-synaptic dopaminergic function. Two PET images from each subject were co-registered using an automated registration program and re-sliced in the coronal section. Accumulation of 11C-CFT and 11C-RAC was evaluated with reference to the cerebellum and a ratio image of 11C-RAC and 11C-CFT accumulation was created. 11C-CFT uptake decreased predominantly in the posterior and dorsolateral part of the putamen. In the same region, 11C-RAC uptake was relatively increased in inverse proportion to 11C-CFT. Thus, the 11C-RAC/ 11C-CFT ratio images demonstrated significant discrepancy of pre- and post-synaptic dopaminergic functions, predominantly in posterior and dorsolateral parts of the putamen contralateral to the side of dominant symptoms, not only in patients with advanced symptoms (HY-III), but also in those with hemi-parkinsonism (HY-I). The combination of 11C-CFT and 11C-RAC PET studies clarified the regional imbalance of striatal dopaminergic function in Parkinson's disease.