Whole body biodistribution and radiation dosimetry in humans of a new PET ligand, [(18)F]-FEPPA, to image translocator protein (18 kDa).
OBJECTIVE
[(18)F]-FEPPA is a translocator protein (18 kDa, TSPO) positron emission tomography (PET) radiotracer. Radiation dosimetry was estimated from the whole body biodistribution, taking into consideration TSPO rs6971 (Ala147Thr) polymorphism.


METHODS
[(18)F]-FEPPA whole body PET scans were acquired for six healthy subjects. Time-activity curves were generated from regions of interest of nine organs, from which normalized accumulated activities were calculated and thus internal dose, using OLINDA/EXM 1.1. Genotyping of rs6971, associated with high- and low-affinity [(18)F]-FEPPA binding (high-affinity binder (HAB) and low-affinity binder (LAB)), was performed.


RESULTS
Five subjects exhibited the C/C (HAB) allele, and the other carried the minor allele T/T (LAB). The LAB whole body biodistribution showed highest radioactivity accumulation in bladder, whereas in HABs, the spleen received the highest dose. The effective dose of the single LAB (16.3 μSv/MBq) was 23 % less than the mean of the HABs (21.0 ± 2.9 μSv/MBq). When including all subjects, the effective dose was 20.2 ± 3.0 μSv/MBq.


CONCLUSIONS
[(18)F]-FEPPA radiation dose is consistent with other (18)F-labeled radioligands and the Ala147Thr genotype agreed with [(18)F]-FEPPA distribution.
Vivian M. Rakoff PET Centre, Research Imaging Centre, Centre for Addiction and Mental Health CAMH, 250 College Street, Toronto, Ontario, Canada, M5T 1R8.
Romina
R
Mizrahi
Pablo M
PM
Rusjan
Irina
I
Vitcu
Alvina
A
Ng
Alan A
AA
Wilson
Sylvain
S
Houle
Peter M
PM
Bloomfield
D000328:Adult; D000813:Anilides / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008024:Ligands; D008297:Male; D009928:Organ Specificity; D049268:Positron-Emission Tomography / Q000379:methods*; D011725:Pyridines / Q000493:pharmacokinetics*; D011874:Radiometry / Q000379:methods*; D018079:Receptors, GABA / Q000378:metabolism*; D014018:Tissue Distribution; D051598:Whole Body Imaging / Q000379:methods*
D000813:Anilides; D008024:Ligands; C530438:N-(2-((N-(4-phenoxypyridin-3-yl)acetamido)methyl)phenoxy)ethyl fluoride; D011725:Pyridines; D018079:Receptors, GABA; C499229:TSPO protein, human