title: Imaging of dopamine transporters and D2 receptors in patients with Parkinson's disease and multiple system atrophy.
abstract: OBJECTIVE
  The aim of this study was to ascertain whether combined presynaptic and postsynaptic dopaminergic single-photon emission computed tomography (SPECT) scanning is useful for differentiation between patients with idiopathic Parkinson's disease (IPD), patients with multiple system atrophy of the striatonigral type (MSA) and healthy subjects.
  
  
  METHODS
  SPECT measurements of the dopamine transporter (DAT) were done with 123I-beta-CIT, while for determination of the dopamine D2-like receptors (D2), 123I-epidepride was used. Clinical evaluation and SPECT scans were carried out in 14 patients with IPD, eight patients with MSA and 11 healthy age-matched control subjects.
  
  
  RESULTS
  Putaminal DAT binding was reduced to 32% of control values in IPD and to 19% of control values in MSA . Significantly higher striatal asymmetry in DAT binding was found in MSA than in controls, but IPD patients had significantly higher asymmetry than MSA patients. Striatal D2 binding did not differ significantly between patients and healthy controls but the ratio between caudate DAT and D2 binding was significantly higher in patients with IPD than in those with MSA, even when disease severity was taken into account.
  
  
  CONCLUSIONS
  Patients with reduced striatal 123I-beta-CIT binding and a side-to-side difference greater than 15% are likely to suffer from IPD. Patients with reduced striatal 123I-beta-CIT binding and a side-to-side difference of between 5% and 15% are more likely to have MSA. 123I-epidepride SPECT measurements may add further diagnostic information, since the ratio between DAT and D2 receptor binding is significantly higher in IPD than in MSA.
authors.affiliation: Neurobiology Research Unit 9201, Department of Neurology, University Hospital Rigshospitalet, Copenhagen, Denmark. gitte@nru.dk
authors.forename: G M
authors.initials: GM
authors.lastname: Knudsen
authors.forename: M
authors.initials: M
authors.lastname: Karlsborg
authors.forename: G
authors.initials: G
authors.lastname: Thomsen
authors.forename: K
authors.initials: K
authors.lastname: Krabbe
authors.forename: L
authors.initials: L
authors.lastname: Regeur
authors.forename: T
authors.initials: T
authors.lastname: Nygaard
authors.forename: C
authors.initials: C
authors.lastname: Videbaek
authors.forename: L
authors.initials: L
authors.lastname: Werdelin
mesh_terms: D000328:Adult; D000368:Aged; D001549:Benzamides / Q000493:pharmacokinetics; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism; D003042:Cocaine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D003937:Diagnosis, Differential; D050483:Dopamine Plasma Membrane Transport Proteins; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008875:Middle Aged; D019578:Multiple System Atrophy / Q000000981:diagnostic imaging* / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000378:metabolism*; D011759:Pyrrolidines / Q000493:pharmacokinetics; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D001549:Benzamides; D050483:Dopamine Plasma Membrane Transport Proteins; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D011759:Pyrrolidines; D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; C493214:SLC6A3 protein, human; C063525:epidepride; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine