[Molecular imaging in Parkinson's disease].

Molecular imaging techniques using PET or SPECT have provided major insights into not only objective diagnosis of Parkinson's disease(PD), but also understanding the pathophysiological process in the disease progression. At disease onset, a compensatory hyperactivity of dopa decarboxylase in the nigrostriatal and extrastriatal dopaminergic pathways and upregulation of postsynaptic D2 receptor have been demonstrated. In the advanced stage, an excessively earlier release of dopamine from the residual neurons has been shown, suggesting a relationship with motor complications. In terms of therapy of PD, functional images have provided some objective evidences for possible neuroprotective effect of dopamine agonists, survival of fetal dopaminergic tissue grafted into patient's putamen, an increase of dopamine release by BDNF focal infusion therapy, and functional modification by deep brain stimulation. In vivo imaging of gene expression under developing may be informative in the future gene therapy in PD.