title: Assessing the optimal time point for the measurement of extrastriatal serotonin transporter binding with 123I-FP-CIT SPECT in healthy, male subjects.
abstract: (123)I-N-ω-fluoropropyl-2β-carboxymethoxy-3β-(4-iodophenyl)nortropane ((123)I-FP-CIT) is commonly used to assess the dopamine transporter in the striatum. However, recent studies suggest that this tracer may be used also to assess binding to monoamine transporters in the midbrain or diencephalon, which may reflect predominantly serotonin transporter (SERT) binding. However, it is still unclear at what time point after injection SPECT should be performed for optimal assessment of SERT with(123)I-FP-CIT. Therefore, we examined the time course of extrastriatal (123)I-FP-CIT binding.
  
  
  METHODS
  Nineteen healthy, male subjects were included, and SPECT images were acquired up to 3 h after (123)I-FP-CIT injection. Region-of-interest analysis was performed, and specific-to-nonspecific binding ratios were calculated.
  
  
  RESULTS
  Specific-to-nonspecific (123)I-FP-CIT binding ratios in the midbrain and diencephalon were significantly higher 2 h after injection than 1 h after injection and remained stable between 2 and 3 h after injection.
  
  
  CONCLUSIONS
  The optimal time frame for assessing (123)I-FP-CIT binding to extrastriatal SERT is between 2 and 3 h after injection of the tracer.
authors.affiliation: Department of Endocrinology and Metabolism, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. k.e.koopman@amc.nl
authors.forename: Karin E
authors.initials: KE
authors.lastname: Koopman
authors.forename: Susanne E
authors.initials: SE
authors.lastname: la Fleur
authors.forename: Eric
authors.initials: E
authors.lastname: Fliers
authors.forename: Mireille J
authors.initials: MJ
authors.lastname: Serlie
authors.forename: Jan
authors.initials: J
authors.lastname: Booij
mesh_terms: D000328:Adult; D002531:Cerebellum / Q000000981:diagnostic imaging / Q000378:metabolism; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism; D004027:Diencephalon / Q000000981:diagnostic imaging / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008636:Mesencephalon / Q000000981:diagnostic imaging / Q000378:metabolism*; D011485:Protein Binding; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D050486:Serotonin Plasma Membrane Transport Proteins / Q000378:metabolism*; D015899:Tomography, Emission-Computed, Single-Photon; D014326:Tropanes / Q000138:chemical synthesis / Q000493:pharmacokinetics; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D050486:Serotonin Plasma Membrane Transport Proteins; D014326:Tropanes; C087552:2-carbomethoxy-8-(3-fluoropropyl)-3-(4-iodophenyl)tropane