title: Dopamine transporter imaging does not predict the number of nigral neurons in Parkinson disease.
abstract: OBJECTIVE
  To examine possible associations between in vivo brain dopamine transporter SPECT imaging and substantia nigra pars compacta (SNc) neuronal survival in Parkinson disease (PD).
  
  
  METHODS
  Nigral neuron numbers were calculated for 18 patients (11 patients with neuropathologically confirmed PD) who had been examined with dopamine transporter (DAT) SPECT before death. Correlation analyses between SNc tyrosine hydroxylase (TH)-positive and neuromelanin-containing neuron counts and DAT striatal specific binding ratios (SBRs) were performed with semiquantitative region of interest-based and voxel-based analyses.
  
  
  RESULTS
  Mean putamen SBR did not correlate with the number of substantia nigra TH-positive (r= -0.11,p= 0.66) or neuromelanin-containing (r= -0.07,p= 0.78) neurons. Correlations remained clearly nonsignificant when the time interval between SPECT and death was used as a covariate, when the voxel-based analysis was used, and when only patients with PD were included.
  
  
  CONCLUSIONS
  This cohort study demonstrates that postmortem SNc neuron counts are not associated with striatal DAT binding in PD. These results fit with the theory that there is no correlation between the number of substantia nigra neurons and striatal dopamine after a certain level of damage has occurred. Striatal DAT binding in PD may reflect axonal dysfunction or DAT expression rather than the number of viable neurons.
authors.affiliation: From the Division of Clinical Neurosciences (L.S., J.J., V.K.), Turku University Hospital, Turku, Finland; Department of Neurology (L.S., J.J., V.K.) and Turku PET Centre (J.J., T.N., V.K.), University of Turku; and Departments of Pathology (K.K., M.G.) and Clinical Physiology and Nuclear Medicine (T.N.), Turku University Hospital and University of Turku, Finland.
authors.forename: Laura
authors.initials: L
authors.lastname: Saari
authors.affiliation: From the Division of Clinical Neurosciences (L.S., J.J., V.K.), Turku University Hospital, Turku, Finland; Department of Neurology (L.S., J.J., V.K.) and Turku PET Centre (J.J., T.N., V.K.), University of Turku; and Departments of Pathology (K.K., M.G.) and Clinical Physiology and Nuclear Medicine (T.N.), Turku University Hospital and University of Turku, Finland.
authors.forename: Katri
authors.initials: K
authors.lastname: Kivinen
authors.affiliation: From the Division of Clinical Neurosciences (L.S., J.J., V.K.), Turku University Hospital, Turku, Finland; Department of Neurology (L.S., J.J., V.K.) and Turku PET Centre (J.J., T.N., V.K.), University of Turku; and Departments of Pathology (K.K., M.G.) and Clinical Physiology and Nuclear Medicine (T.N.), Turku University Hospital and University of Turku, Finland.
authors.forename: Maria
authors.initials: M
authors.lastname: Gardberg
authors.affiliation: From the Division of Clinical Neurosciences (L.S., J.J., V.K.), Turku University Hospital, Turku, Finland; Department of Neurology (L.S., J.J., V.K.) and Turku PET Centre (J.J., T.N., V.K.), University of Turku; and Departments of Pathology (K.K., M.G.) and Clinical Physiology and Nuclear Medicine (T.N.), Turku University Hospital and University of Turku, Finland.
authors.forename: Juho
authors.initials: J
authors.lastname: Joutsa
authors.affiliation: From the Division of Clinical Neurosciences (L.S., J.J., V.K.), Turku University Hospital, Turku, Finland; Department of Neurology (L.S., J.J., V.K.) and Turku PET Centre (J.J., T.N., V.K.), University of Turku; and Departments of Pathology (K.K., M.G.) and Clinical Physiology and Nuclear Medicine (T.N.), Turku University Hospital and University of Turku, Finland.
authors.forename: Tommi
authors.initials: T
authors.lastname: Noponen
authors.affiliation: From the Division of Clinical Neurosciences (L.S., J.J., V.K.), Turku University Hospital, Turku, Finland; Department of Neurology (L.S., J.J., V.K.) and Turku PET Centre (J.J., T.N., V.K.), University of Turku; and Departments of Pathology (K.K., M.G.) and Clinical Physiology and Nuclear Medicine (T.N.), Turku University Hospital and University of Turku, Finland. valtteri.kaasinen@tyks.fi.
authors.forename: Valtteri
authors.initials: V
authors.lastname: Kaasinen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002452:Cell Count; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008543:Melanins / Q000378:metabolism; D008875:Middle Aged; D009474:Neurons / Q000473:pathology*; D010300:Parkinson Disease / Q000000981:diagnostic imaging / Q000473:pathology*; D011485:Protein Binding / Q000502:physiology; D012189:Retrospective Studies; D013378:Substantia Nigra / Q000000981:diagnostic imaging / Q000473:pathology*; D015899:Tomography, Emission-Computed, Single-Photon; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
chemical_list: D050483:Dopamine Plasma Membrane Transport Proteins; D008543:Melanins; C014121:neuromelanin; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine