Biodistribution and radiation dosimetry in humans of a new PET ligand, (18)F-PBR06, to image translocator protein (18 kDa).
As a PET biomarker for inflammation, translocator protein (18 kDa) (TSPO) can be measured with an (18)F-labeled aryloxyanilide, (18)F-N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline ((18)F-PBR06), in the human brain. The objective of this study was to estimate the radiation absorbed doses of (18)F-PBR06 based on biodistribution data in humans.


METHODS
After the injection of (18)F-PBR06, images were acquired from head to thigh in 7 healthy humans. Urine was collected at various time points. Radiation absorbed doses were estimated by the MIRD scheme.


RESULTS
Moderate to high levels of radioactivity were observed in organs with high densities of TSPO and in organs of metabolism and excretion. Bone had low levels of radioactivity. The effective dose was 18.5 muSv/MBq.


CONCLUSIONS
The effective dose of (18)F-PBR06, compared with other (18)F radioligands, was moderate. This radioligand had negligible defluorination, as indirectly assessed by bone radioactivity. Doses to the gallbladder wall and spleen may limit the amount of permissible injected radioactivity.
Fujimura
Yota
Y
Molecular Imaging Branch, National Institute of Mental Health, National Institutes of Health, Bethesda, Maryland 20892-2035, USA.
Kimura
Yasuyuki
Y
Siméon
Fabrice G
FG
Dickstein
Leah P
LP
Pike
Victor W
VW
Innis
Robert B
RB
Fujita
Masahiro
M
D000083:Acetanilides / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000494:pharmacology; D000328:Adult; D001711:Biotransformation; D001794:Blood Pressure / Q000187:drug effects; D001842:Bone and Bones / Q000378:metabolism; D004562:Electrocardiography / Q000187:drug effects; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D049268:Positron-Emission Tomography; D011874:Radiometry; D019275:Radiopharmaceuticals / Q000008:administration & dosage* / Q000493:pharmacokinetics* / Q000494:pharmacology; D018079:Receptors, GABA / Q000378:metabolism*; D015656:Respiratory Mechanics / Q000187:drug effects; D014018:Tissue Distribution
D000083:Acetanilides; C538798:N-fluoroacetyl-N-(2,5-dimethoxybenzyl)-2-phenoxyaniline; D019275:Radiopharmaceuticals; D018079:Receptors, GABA; C499229:TSPO protein, human