Biodistribution and radiation dosimetry of the dopamine D2 ligand 11C-raclopride determined from human whole-body PET.
Whole-body radiation dosimetry of 11C-raclopride was performed in healthy human volunteers.


METHODS
Subjects (n = 6) were scanned with PET. Subjects received single-bolus injections of 11C-raclopride (S-(-)-3,5-dichloro-N-[(1-ethyl-2-pyrrolidinyl)]methyl-2-hydroxy-6-methoxybenzamide) (533 +/- 104 MBq) and were scanned for approximately 110 min with a 2-dimensional whole-body protocol. Regions of interest were placed over all visually identifiable organs and time-activity curves were generated. Residence times were computed as the area under the curve of the time-activity curves, normalized to injected activities and standard values of organ volumes. Absorbed doses were computed according to the MIRD schema with MIRDOSE3.1 software.


RESULTS
Organs with the highest radiation burden were gallbladder wall, small intestine, liver, and urinary bladder wall.


CONCLUSIONS
On the basis of the estimated absorbed dose, the maximum allowable single study dose under U.S. federal regulations for studies performed under Radiation Drug Research Committee is 1.58 GBq (42.8 mCi). This is still considerably higher than the doses of 11C-raclopride commonly used in research PET (370-555 MBq).
Slifstein
Mark
M
Department of Psychiatry, Columbia University, New York, New York 10032, USA. mms218@columbia.edu
Hwang
Dah-Ren
DR
Martinez
Diana
D
Ekelund
Jesper
J
Huang
Yiyun
Y
Hackett
Elizabeth
E
Abi-Dargham
Anissa
A
Laruelle
Marc
M
D000328:Adult; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D009928:Organ Specificity; D020891:Raclopride / Q000493:pharmacokinetics*; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D017448:Receptors, Dopamine D2 / Q000378:metabolism*; D014018:Tissue Distribution; D051598:Whole Body Imaging / Q000379:methods; D014915:Whole-Body Counting / Q000379:methods*
D019275:Radiopharmaceuticals; D017448:Receptors, Dopamine D2; D020891:Raclopride