Radiosynthesis and evaluation of two novel 123I-labeled 2-methyl-4-nitroimidazole derivatives as potential infection imaging agents

The 123I-labeled tracers were obtained in moderate to good radiochemical yields (34-80%) and acceptable radiochemical purities (93-99%). In contrast to 123I-labeled ornidazole, 1-[(1-hydroxy-3-[123I]iodoprop-2-yloxy)methyl]-2-methyl-4-nitroimidazole (2) and 1-[(1-[123I]iodoprop-2-yloxy)methyl]-2-methyl-4-nitroimidazole (3) showed high serum stability. Compared to noninfected controls, all of the 123I-labeled tracers showed increased uptake at the area of induced infection after 6 and 24 h, but the uptake was significantly lower than in the case of 67Ga over the same period. Tracer 3 showed a slightly superior uptake after 6 h than the other 123I-labeled tracers over the same period. The advantage of the initially slightly faster rate at which nitroimidazole tracers appear to accumulate in the infection area in comparison to 67Ga might not outweigh the advantage of the eventual higher target to nontarget ratio displayed by 67Ga.