title: Pre- and postsynaptic dopamine SPECT in the early phase of idiopathic parkinsonism: a population-based study.
abstract: OBJECTIVE
  The aim of this study was to assess the diagnostic contribution of pre- and postsynaptic dopamine SPECT in drug-naïve patients with early idiopathic parkinsonism and to investigate possible differences between idiopathic Parkinson's disease (PD) and atypical parkinsonian syndromes (APS) and possible differences in motor subtypes of parkinsonism.
  
  
  METHODS
  A group of 128 newly diagnosed idiopathic parkinsonian patients and 48 healthy controls was studied. Presynaptic baseline SPECT with (123)I-FP-CIT was performed in all patients and in 120 patients also a baseline postsynaptic SPECT with (123)I-IBZM. Clinical diagnoses were reassessed after 12 months.
  
  
  RESULTS
  Presynaptic uptake in the putamen and caudate was significantly reduced in patients compared to controls. Presynaptic uptake ratios were not different between PD patients and patients with APS, and postsynaptic uptake in APS was not significantly reduced compared to PD or controls. In half of the APS patients both pre- and postsynaptic uptake ratios were reduced on the same side in the striatum. Impaired motor performance was associated with decreased presynaptic uptake in the putamen in PD. The postural instability and gait difficulty (PIGD) subtype of PD had lower presynaptic uptake ratios than patients with tremor-dominated (TD) symptoms.
  
  
  CONCLUSIONS
  Not only presynaptic putamen uptake ratios, but also caudate ratios were reduced in a majority of the patients in our study. At baseline scan, i.e. in an early stage of the disease, the accuracy of excluding APS in the whole study population was 85% using a combination of pre- and postsynaptic SPECT. Already at baseline, lower presynaptic SPECT ratios were seen in PD with PIGD at onset compared to those with TD subtype.
authors.affiliation: Department of Radiation Sciences, Diagnostic Radiology, Umeå University, 901 85, Umeå, Sweden. susanna.jakobson.mo@diagrad.umu.se
authors.forename: Susanna Jakobson
authors.initials: SJ
authors.lastname: Mo
authors.forename: Jan
authors.initials: J
authors.lastname: Linder
authors.forename: Lars
authors.initials: L
authors.lastname: Forsgren
authors.forename: Anne
authors.initials: A
authors.lastname: Larsson
authors.forename: Lennart
authors.initials: L
authors.lastname: Johansson
authors.forename: Katrine
authors.initials: K
authors.lastname: Riklund
mesh_terms: D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D003937:Diagnosis, Differential; D004298:Dopamine / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D010300:Parkinson Disease / Q000000981:diagnostic imaging* / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D017448:Receptors, Dopamine D2 / Q000378:metabolism; D012737:Sex Factors; D013569:Synapses; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D017448:Receptors, Dopamine D2; D004298:Dopamine