Whole-body biodistribution and radiation dosimetry estimates for the PET dopamine transporter probe 18F-FECNT in non-human primates.
OBJECTIVE
2 beta-Carbomethoxy-3-(4-chlorophenyl)-8-(2-[18F]fluoroethyl)nortropane (18F-FECNT) is a selective radioligand for the in vivo quantification of dopamine transporters by using positron emission tomography. The aim of the current study was to quantify the distribution of radioactivity in three rhesus monkeys after the injection of approximately 185 MBq (5 mCi) of 18F-FECNT.


METHODS
Whole-body images were acquired at 23-30 time points for a total of 220 min following injection of the radioligand. Source organs were identified at each time point from planar images.


RESULTS
The peak activities in planar images in the six identified source organs (expressed as per cent injected dose (%ID)) were lungs (16.5%ID at 2 min), kidneys (12.5%ID at 3 min), brain (9.5%ID at 6 min), liver (7.5%ID at 3 min), red bone marrow (3.5%ID at 12 min), and urinary bladder (2%ID at 98 min). Radiation absorbed doses were calculated using the gastrointestinal tract model in two ways: (1) assuming no urine voiding, and (2) using a dynamic bladder model with voiding intervals of 2.4 and 4.8 h. Using the gastrointestinal tract model and dynamic bladder model with a voiding interval 4.8 h, the three organs with highest exposure (in mu Gy.MBq(-1) (mrad.mCi(-1)) were kidneys 75.68 (280), lungs 44.86 (166) and urinary bladder 58.38 (216). Effective doses estimated with and without urine voiding were in the range 21.35-22.70 mu Gy.MBq(-1) (79-84 mrad.mCi(-1)).


CONCLUSIONS
The estimated radiation burden of 18F-FECNT is relatively modest and would allow multiple scans per research subject per year.
Tipre
Dnyanesh N
DN
Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bldg 1 Rm. B3-10, 1 Center Drive, Bethesda, MD 20892-0135, USA. TipreD@intra.nimh.nih.gov
Fujita
Masahiro
M
Chin
Frederick T
FT
Seneca
Nicholas
N
Vines
Douglas
D
Liow
Jeih-San
JS
Pike
Victor W
VW
Innis
Robert B
RB
D000818:Animals; D001822:Body Burden; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D004353:Drug Evaluation, Preclinical; D006801:Humans; D008253:Macaca mulatta; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009662:Nortropanes / Q000493:pharmacokinetics*; D009928:Organ Specificity; D049268:Positron-Emission Tomography / Q000379:methods; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D012062:Relative Biological Effectiveness; D014018:Tissue Distribution; D014915:Whole-Body Counting / Q000379:methods*
C410211:2-carbomethoxy-3-(4-chlorophenyl)-8-(2-fluoroethyl)nortropane; D050483:Dopamine Plasma Membrane Transport Proteins; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D009662:Nortropanes; D019275:Radiopharmaceuticals