1 Jewish General Hospital and Lady Davis Institute for Medical Research, 3755 Chemin de la Cote St. Cathérine, Montreal, Québec, H3T 1E2, Canada. alexander.thiel@mcgill.ca.
2 Department of Neurology & Neurosurgery, McGill Univesrity, Montreal, Canada. alexander.thiel@mcgill.ca.
3 Department of Neurology & Neurosurgery, McGill Univesrity, Montreal, Canada.
4 Brain Imaging Center, Montreal Neurological Institute, Montreal, Canada.
5 Department of Chemistry, McGill University, Montreal, Canada.
6 Jewish General Hospital and Lady Davis Institute for Medical Research, 3755 Chemin de la Cote St. Cathérine, Montreal, Québec, H3T 1E2, Canada.
7 Medical Physics Unit, McGill University, Montreal, Canada.
8 PERFORM Centre Concordia University, Montreal, Canada.
9 Cross Cancer Institute, Medical Isotope Cyclotron Facility, University of Alb

Background: Reduced expression or impaired signalling of tropomyosin receptor kinases (Trk receptors) are found in a vast spectrum of CNS disorders. [¹⁸F]TRACK is the first PET radioligand for TrkB/C with proven in vivo brain penetration and on-target specific signal. Here we report dosimetry data for [¹⁸F]TRACK in healthy humans. 6 healthy participants (age 22-61 y, 3 female) were scanned on a General Electric Discovery PET/CT 690 scanner. [¹⁸F]TRACK was synthesized with high molar activities (A_m = 250 ± 75 GBq/µmol), and a dynamic series of 12 whole-body scans were acquired after injection of 129 to 147 MBq of the tracer. Images were reconstructed with standard corrections using the manufacturer's OSEM algorithm. Tracer concentration time-activity curves (TACs) were obtained using CT-derived volumes-of-interest. Organ-specific doses and the total effective dose were estimated using the Committee on Medical Internal Radiation Dose equation for adults and tabulated Source tissue values (S values).

Results: Average organ absorbed dose was highest for liver and gall bladder with 6.1E-2 (± 1.06E-2) mGy/MBq and 4.6 (± 1.18E-2) mGy/MBq, respectively. Total detriment weighted effective dose E_DW was 1.63E-2 ± 1.68E-3 mSv/MBq. Organ-specific TACs indicated predominantly hepatic tracer elimination.

Conclusion: Total and organ-specific effective doses for [¹⁸F]TRACK are low and the dosimetry profile is similar to other ¹⁸F-labelled radio tracers currently used in clinical settings.