Biodistribution and Radiation Dosimetry of 4-[¹⁸F]fluorobenzylguanidine derived from PET Imaging in Non-Human Primates

Objectives: This study was designed to determine the distribution pattern of 4-[¹⁸F]fluorobenzylguanidine (¹⁸F-PFBG) in non-human primates (NHP) and to estimate the radiation dosimetry of ¹⁸F-PFBG as derived from PET imaging in NHP.

Methods: Whole body PET images were acquired of three male cynomolgus monkeys after intravenous (i.v.) administration of 269 ± 51 MBq of ¹⁸F-PFBG. Twenty-one whole body frames were acquired over 150 min post-administration. Regions of interest (ROIs) were placed on identifiable organs and time activity curves (TACs) were generated. Residence times were derived from the TACs and OLINDA/EXM 1.0 was used to produce radiation absorbed dose estimates for the 70-kg male, 15-year old, 5-year old, and 1-year old models. Results: Rapid uptake was observed in the heart, liver, kidneys, spleen, adrenal glands, parotid glands, and submandibular glands (Fig. 1). The uptake in heart wall, liver, lungs, spleen, and adrenal glands at 6.0 min was 1.41 ± 0.16 %ID, 23.89 ± 9.14 %ID, 2.72 ± 0.41 %ID, 1.09 ± 0.25 %ID, and 0.41 ± 0.08 %ID, respectively. Radioactivity accumulated in the bladder over time and corresponded with a decrease in radioactivity in the kidney. Total radioactivity in the kidney and bladder at 6 min was 14.68 ± 6.22 %ID and 2.84 ± 4.68 %ID and 1.74 ± 0.80 %ID and 34.51 ± 6.11 %ID at 153 min. The mean residence times for ¹⁸F-PFBG in the brain, liver, lungs, kidneys, muscles, heart wall, pancreas, and adrenal glands were 0.38 ± 0.04, 23.40 ± 5.71, 2.37 ± 0.44, 5.48 ± 3.23, 36.63 ± 4.35, 1.27 ± 0.09, 0.88 ± 0.16, and 0.37 ± 0.01 min. The mean effective dose for ¹⁸F- PFBG was 0.04 ± 0.00, 0.07 ± 0.00, 0.36 ± 0.04, 0.43 ± 0.05 and 0.62 ± 0.06 mSv/MBq for the 70-kg adult, 15-year old, 10-year old, 5-year old and 1-year old models, respectively. The organs receiving the highest radiation absorbed dose from ¹⁸F-PFBG exposure in the 70-kg adult were the urinary bladder wall (0.24 ± 0.06 mGy/MBq), testes (0.09 ± 0.01 mGy/MBq), adrenal glands (0.07 ± 0.00 mGy/MBq), kidneys (0.06 ± 0.03 mGy/MBq) and liver (0.05 ± 0.01 mGy/MBq). Conclusions: The radiation burden estimated from PET imaging of non-human primates after administration of ¹⁸F-PFBG appears to be modest and compares well with other radiolabeled guanidine analogs.

• Download figure
• Open in new tab
• Download powerpoint