3-fluoro-2-(4-((2-nitro-1h-imidazol-1-yl)methyl)-1h-1-2-3-triazol-1-yl)propan-1-ol and Hypoxia

In the past 25 y, a large amount of clinical experience with hypoxia PET tracers has accumulated. This article discusses recent improvements in image acquisition protocols and tracer pharmacology that have resulted in improved understanding of the underlying physiologic processes. The widespread clinical adoption of hypoxia PET tracers will depend largely on their utility in treatment prescription and in outcome monitoring. The establishment and validation of hypoxia-directed treatment protocols are still under development, and it is envisaged that the design and use of future hypoxia PET tracers will develop as part of this process.

Topics: Etanidazole; Humans; Hydrocarbons, Fluorinated; Hypoxia; Nitroimidazoles; Positron-Emission Tomography; Radioactive Tracers; Triazoles

F-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-HX4 using whole-body PET/computed tomography (CT) scans in monkeys and humans.. Successive whole-body PET/CT scans were done after the injection of F-HX4 in four healthy humans (422±142 MBq) and in three rhesus monkeys (189±3 MBq). Biodistribution was determined from PET images and organ doses were estimated using OLINDA/EXM software.. 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 3.6 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 μGy/MBq (humans), in the 4.8-h bladder voiding interval model. The average value of effective dose for the adult male was estimated at 42±4.2 μSv/MBq from monkey data and 27±2 μSv/MBq from human data.. Bladder, kidneys, and liver have the highest uptake of injected F-HX4 activity for both monkeys and humans. The urinary bladder wall receives the highest dose of F-HX4 and is the critical organ. Thus, patients should be encouraged to maintain adequate hydration and void frequently. The effective dose of F-HX4 is comparable with that of other F-based imaging agents.

Topics: Animals; Biomarkers; Female; Haplorhini; Humans; Hypoxia; Male; Middle Aged; Nitroimidazoles; Positron-Emission Tomography; Radiometry; Radiopharmaceuticals; Species Specificity; Tomography, X-Ray Computed; Triazoles; Whole Body Imaging

[(18)F]HX4 is a 2-nitroimidazole based investigational radiotracer for imaging hypoxia.. A two-step, one-pot synthetic procedure was developed on a GE Tracerlab MX-FDG with a disposable cassette. Nucleophilic substitution of a nosylate group with [(18)F]fluoride was followed by solvent evaporation and acidic removal of the acetyl protecting group. HPLC purification in a bio-compatible solvent mixture was developed.. Using starting activities of 80-110 GBq [(18)F]fluoride, GMP compliant [(18)F]HX4 was produced in non-decay corrected radiochemical yields of 12 ± 3% (n = 9) in 55 min including HPLC purification. No reformulation steps were required. The mean specific activity of the final product was 2450 GBq/μmol. Modifications to the process and final formulation were included to prevent decomposition of the product, and these changes resulted in an improved stability of the formulated [(18)F]HX4, with a shelf-life of at least 8h post-synthesis. The product consistently passed all required quality control tests to determine that the [(18)F]HX4 was suitable for clinical use. Using a 90 minute target bombardment, and 80-110 GBq starting [(18)F]fluoride, the method produced multiple patient doses.

Topics: Automation; Hypoxia; Nitroimidazoles; Positron-Emission Tomography; Quality Control; Radiochemistry; Triazoles