title: Whole-body biodistribution, radiation absorbed dose and brain SPECT imaging with iodine-123-beta-CIT in healthy human subjects.
abstract: SPECT imaging with 123I-labeled methyl 3 beta-(4-iodophenyl)tropane-2 beta-carboxylate ([123I]beta-CIT) in nonhuman primates has shown brain striatal activity, which primarily reflects binding to the dopamine transporter. The biodistribution and calculated radiation-absorbed doses of [123I]beta-CIT administered to eight healthy subjects were measured with attention to the accurate determination of organ time-activity data.
  
  
  METHODS
  Whole-body transmission images were obtained with a scanning line source for attenuation correction of the emission images. Following administration of 92.5 +/- 22.2 MBq (2.5 +/- 0.6 mCi) of [123I]beta-CIT, subjects were imaged with a whole-body imager every 30 min for 3 hr, every 60 min for the next 3 hr and at 12, 24 and 48 hr postinjection. Regional body conjugate counts were converted to microcuries of activity, with a calibration factor determined in a separate experiment using a distributed source of 123I.
  
  
  RESULTS
  The peak brain uptake represented 14% of the injected dose, with 2% of the activity approximately overlying the striatal region. Highest radiation-absorbed doses were to the lung (0.1 mGy/MBq, 0.38 rads/mCi), liver (0.087 mGy/MBq, 0.32 rads/mCi) and lower large intestine (0.053 mGy/MBq, 0.20 rads/mCi).
  
  
  CONCLUSIONS
  Iodine-123-beta-CIT is a promising SPECT agent for imaging of the dopamine transporter in humans with favorable dosimetry and high brain uptake.
authors.affiliation: Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut.
authors.forename: J P
authors.initials: JP
authors.lastname: Seibyl
authors.forename: E
authors.initials: E
authors.lastname: Wallace
authors.forename: E O
authors.initials: EO
authors.lastname: Smith
authors.forename: M
authors.initials: M
authors.lastname: Stabin
authors.forename: R M
authors.initials: RM
authors.lastname: Baldwin
authors.forename: S
authors.initials: S
authors.lastname: Zoghbi
authors.forename: Y
authors.initials: Y
authors.lastname: Zea-Ponce
authors.forename: Y
authors.initials: Y
authors.lastname: Gao
authors.forename: W Y
authors.initials: WY
authors.lastname: Zhang
authors.forename: J L
authors.initials: JL
authors.lastname: Neumeyer
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D003042:Cocaine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D008297:Male; D011829:Radiation Dosage; D014018:Tissue Distribution; D015899:Tomography, Emission-Computed, Single-Photon
chemical_list: D007457:Iodine Radioisotopes; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine