[Muscarinic cholinergic receptor imaging of parkinsonian brain using 11C-NMPB and PET]

11C-NMPB is a useful ligand which is used to measure brain muscarinic cholinergic receptors (mAChRs) for its high affinity and high brain uptake. PET images of 11C-NMPB uptake had the highest accumulations in the cerebral cortex and striatum and the lowest in the cerebellum, both in patients with Parkinson's disease (PD) and normal subjects. 11C-NMPB uptake was homogeneous throughout the cerebral cortex in the normal subjects but greater in the frontal cortex of about one half of the PD patients as compared with other cerebral cortical areas. Quantitative analysis showed that the PD patients had high K3 values, an index of mAChR binding, in the frontal cortex. In PD, increased mAChR binding in the frontal cortex may be related to frontal lobe dysfunction. This technique should prove useful for detecting subclinical impairment of the central cholinergic system in PD.