Biodistribution and radiation dosimetry of the hypoxia marker 18F-HX4 in monkeys and humans determined by using whole-body PET/CT

Objectives F-18-HX4 is a novel positron emission tomography (PET) tracer for imaging hypoxia The purpose of this study was to determine the biodistribution and estimate the radiation dose of F-18 HX4 using whole-body PET/computed tomography (CT) scans in monkeys and humans Methods Successive whole-body PET/CT scans were done after the injection of 18F HX4 in four healthy humans (422 +/- 142 MBq) and in three rhesus monkeys (189 +/- 3 MBq) Biodistnbution was determined from PET images and organ doses were estimated using OLINDA/EXM software Results The bladder, liver, and kidneys showed the highest percentage of the injected radioactivity for humans and monkeys For humans, approximately 45% of the activity is eliminated by bladder voiding in 36 h, and for monkeys 60% is in the bladder content after 3 h The critical organ is the urinary bladder wall with the highest absorbed radiation dose of 415 +/- 18 (monkeys) and 299 +/- 38 mu Gy/MBq (humans), in the 48-h bladder voiding interval model The average value of effective dose for the adult male was estimated at 42 +/- 4 2 mu Sv/MBq from monkey data and 27 +/- 2 mu Sv/MBq from human data Conclusion Bladder, kidneys, and liver have the highest uptake of injected F-18-HX4 activity for both monkeys and humans The urinary bladder wall receives the highest dose of F-18-HX4 and is the critical organ Thus, patients should be encouraged to maintain adequate hydration and void frequently The effective dose of 18F-HX4 is comparable with that of other F-18-based imaging agents Nucl Med Commun 31 1016-1024 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins