Abstract
18F-THK-5351 is a novel radiotracer that demonstrates high binding selectivity and affinity for tau pathology and exhibits better pharmacokinetics in the living brain than previous THK tau probes. The aim of the present study was to estimate the radiation dose of 18F-THK-5351 in humans and to compare the clinical radiation dosimetry results to estimations published previously with preclinical data. Methods: Serial whole-body positron emission tomography/computed tomography (PET/CT) imaging was performed for 240 min on 12 healthy volunteers after injecting 18F-THK-5351 (mean administered activity: 377.8 ± 14.0 MBq, range: 340–397 MBq). The bladder and gallbladder were delineated on PET images, while the other organs were delineated on CT images. Voided urine activity was recorded. The decay-corrected and normalized 18F-THK-5351 activity of 15 source organ regions as a function of time was entered into the OLINDA/EXM software to calculate the effective dose for each subject following the medical internal radiation dosimetry schema. Results: Overall, the 18F-THK-5351 injection was well tolerated. The highest mean initial uptakes at 10 min post-injection were measured in the liver (11.4 ± 2.0%), lung (5.7 ± 2.1%), intestine (3.4 ± 0.8%), and kidney (1.4 ± 0.3%). The highest mean absorbed doses of radiation were in the gallbladder wall (242.2 ± 105.2 µGy/MBq), upper large intestine (90.0 ± 15.8 µGy/MBq), small intestine (79.5 ± 13.8 µGy/MBq), and liver (55.8 ± 6.1 µGy/MBq). The resultant whole-body effective dose was 22.7 ± 1.3 µSv/MBq. Conclusion: Our results suggest that a routine injection of 370 MBq of 18F-THK-5351 would lead to an estimated effective dose of 8.4 mSv; hence, 18F-THK-5351 shows similar radiation burdens to other commonly used clinical tracers. Our findings in humans were compatible with recently published preclinical dosimetry data extrapolated from mice.
- Molecular Imaging
- Neurology
- PET
- Radiotracer Tissue Kinetics
- 18F-THK-5351
- Alzheimers disease
- radiation dosimetry
- tau
- whole body biodistribution
- Copyright © 2017 by the Society of Nuclear Medicine and Molecular Imaging, Inc.