Regional metabolic changes in parkinsonian patients with normal dopaminergic imaging

Mov Disord. 2007 Jan 15;22(2):167-73. doi: 10.1002/mds.21185.


Dopaminergic imaging has been found to be normal in approximately 15% of parkinsonian patients enrolled in neuroprotective trials. We used (18)F-fluorodeoxyglucose positron emission tomography (FDG PET) to determine the metabolic basis for this finding. We reviewed scans from 185 patients with clinical signs of Parkinson's disease (PD) who underwent (18)F-fluorodopa PET imaging for diagnostic confirmation. Of this group, 27 patients (14.6%) had quantitatively normal scans; 8 of these patients were additionally scanned with FDG PET. Pattern analysis was performed on an individual scan basis to determine whether the metabolic changes were consistent with classic PD. Computer-assisted single-case assessments of the FDG PET scans of these 8 patients did not disclose patterns of regional metabolic change compatible with classical PD or an atypical parkinsonian variant. Similarly, network quantification revealed that PD-related pattern expression was not elevated in these patients as it was in an age- and duration-matched cohort with classical PD (P < 0.0001). None of these patients developed clinical signs of classical PD or of an atypical parkinsonian syndrome at a follow-up visit conducted 3 years after imaging. The results suggest that parkinsonian subjects with normal dopaminergic imaging do not have evidence of classical PD or an atypical parkinsonian syndrome.

MeSH terms

  • Brain / metabolism*
  • Corpus Striatum / metabolism
  • Dihydroxyphenylalanine / analogs & derivatives*
  • Dihydroxyphenylalanine / pharmacokinetics
  • Dopamine / metabolism*
  • Dopamine / physiology
  • Female
  • Ganglia / metabolism
  • Ganglia / pathology
  • Humans
  • Male
  • Middle Aged
  • Multiple System Atrophy / epidemiology
  • Multiple System Atrophy / metabolism
  • Occipital Lobe / metabolism
  • Parkinson Disease / epidemiology*
  • Parkinson Disease / metabolism*
  • Positron-Emission Tomography*
  • Putamen / metabolism
  • Retrospective Studies
  • Spinocerebellar Degenerations / epidemiology
  • Spinocerebellar Degenerations / metabolism
  • Spinocerebellar Degenerations / pathology
  • Supranuclear Palsy, Progressive / epidemiology
  • Supranuclear Palsy, Progressive / metabolism


  • fluorodopa F 18
  • Dihydroxyphenylalanine
  • Dopamine