Radiation dosimetry and biodistribution of the TSPO ligand 11C-DPA-713 in humans.

UNLABELLED Whole-body PET/CT was used to characterize the radiation dosimetry of (11)C-DPA-713, a specific PET ligand for the assessment of translocator protein. METHODS Six healthy control subjects, 3 men and 3 women, underwent whole-body dynamic PET scans after bolus injection of (11)C-DPA-713. Subjects were scanned from head to mid thigh with 7 passes performed, with a total PET acquisition of approximately 100 min. Time-activity curves were generated in organs with visible tracer uptake, and tissue residence times were calculated. Whole-body dosimetry was calculated using OLINDA 1.1 software, assuming no voiding. RESULTS The absorbed dose is highest in the lungs, spleen, kidney, and pancreas. The lungs were determined to be the dose-limiting organ, with an average absorbed dose of 2.01 × 10(-2) mSv/MBq (7.43 × 10(-2) rem/mCi). On the basis of exposure limits outlined in the U.S. Food and Drug Administration Code of Federal Regulations (21CFR361.1), the single-dose limit for (11)C-DPA-713 radiotracer injection is 2,487.6 MBq (67.3 mCi). CONCLUSION (11)C-DPA-713 has an uptake pattern that is consistent with the biodistribution of translocator protein and yields a dose burden that is comparable to that of other (11)C-labeled PET tracers.