Evaluation of the biodistribution and radiation dosimetry of the ¹⁸F-labelled amyloid imaging probe [¹⁸F]FACT in humans

Background: The biodistribution and radiation dosimetry of the ¹⁸F-labelled amyloid imaging probe ([¹⁸F] FACT) was investigated in humans. Methods: Six healthy subjects (three males and three females) were enrolled in this study. An average of 160.8 MBq of [¹⁸F] FACT was intravenously administered, and then a series of whole-body PET scans were performed. Nineteen male and 20 female source organs, and the remainder of the body, were studied to estimate time-integrated activity coefficients. The mean absorbed dose in each target organ and the effective dose were estimated from the time-integrated activity coefficients in the source organs. Biodistribution data from [¹⁸F] FACT in mice were also used to estimate absorbed doses and the effective dose in human subjects; this was compared with doses of [¹⁸F] FACT estimated from human PET data. Results: The highest mean absorbed doses estimated using human PET data were observed in the gallbladder (333 ± 251 μGy/MBq), liver (77.5 ± 14.5 μGy/MBq), small intestine (33.6 ± 30.7 μGy/MBq), upper large intestine (29.8 ± 15.0 μGy/MBq) and lower large intestine (25.2 ± 12.6 μGy/MBq). The average effective dose estimated from human PET data was 18.6 ± 3.74 μSv/MBq. The highest mean absorbed dose value estimated from the mouse data was observed in the small intestine (38.5 μGy/MBq), liver (25.5 μGy/MBq) and urinary bladder wall (43.1 μGy/MBq). The effective dose estimated from the mouse data was 14.8 μSv/MBq for [¹⁸F] FACT. Conclusions: The estimated effective dose from the human PET data indicated that the [¹⁸F] FACT PET study was acceptable for clinical purposes.