title: Whole-body distribution and radiation dosimetry of 11C-(+)-PHNO, a D2/3 agonist ligand.
abstract: Using PET, we measured the whole-body distribution of (11)C-(+)-PHNO ((11)C-(+)-4-propyl-9-hydroxynaphthoxazine), a D(2/3) agonist, as a function of time in adult subjects in order to determine the internal radiation dose.
  
  
  METHODS
  PET whole-body data were acquired after the injection of (11)C-(+)-PHNO (∼360 MBq) in 6 healthy subjects (3 male and 3 female). The PET acquisition duration was a maximum of 112.5 min, and 9 discrete time frames were obtained. After reconstruction of the emission data, 6 organs were identified in the images as exhibiting uptake above background levels. Regions of interest were delineated on these organs, and time-activity curves were generated. The time-activity curve data were corrected for the injected activity, specific organ density, and volume, from which normalized accumulated activities (previously known as residence times) were calculated. The normalized accumulated activities were then used with the software code OLINDA/EXM 1.1 to calculate the internal doses for the standard adult male and female models.
  
  
  RESULTS
  The mean effective dose was estimated to be 4.5 ± 0.3 μSv/MBq when all subjects were included and the male model was applied for the dosimetry calculation, and the mean effective dose was estimated to be 5.2 ± 0.2 μSv/MBq when the females were considered separately and the female model was applied for the calculation. The organ receiving the highest dose was the liver (17.9 ± 3.9 μSv/MBq), followed by the kidneys (14.3 ± 3.6 μSv/MBq) and the urinary bladder wall (13.5 ± 3.7 μSv/MBq).
  
  
  CONCLUSIONS
  The estimated radiation doses for (11)C-(+)-PHNO are similar to those reported for other radiotracers labeled with (11)C. (11)C-(+)-PHNO may be used for multiple PET scans in the same subject and remain within regulatory guidelines.
authors.affiliation: Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
authors.forename: Romina
authors.initials: R
authors.lastname: Mizrahi
authors.forename: Pablo
authors.initials: P
authors.lastname: Rusjan
authors.forename: Irina
authors.initials: I
authors.lastname: Vitcu
authors.forename: Alvina
authors.initials: A
authors.lastname: Ng
authors.forename: Alan A
authors.initials: AA
authors.lastname: Wilson
authors.forename: Sylvain
authors.initials: S
authors.lastname: Houle
authors.forename: Peter M
authors.initials: PM
authors.lastname: Bloomfield
mesh_terms: D000328:Adult; D018491:Dopamine Agonists / Q000493:pharmacokinetics* / Q000494:pharmacology; D005260:Female; D006801:Humans; D008024:Ligands; D008297:Male; D009929:Organ Size; D010078:Oxazines / Q000493:pharmacokinetics* / Q000494:pharmacology; D049268:Positron-Emission Tomography; D011874:Radiometry; D017448:Receptors, Dopamine D2 / Q000819:agonists*; D050637:Receptors, Dopamine D3 / Q000819:agonists*; D014018:Tissue Distribution
chemical_list: D018491:Dopamine Agonists; D008024:Ligands; D010078:Oxazines; D017448:Receptors, Dopamine D2; D050637:Receptors, Dopamine D3; C042631:naxagolide