Imaging
hypoxia using positron emission tomography (PET) is of great importance for
therapy of
cancer. [(18)F]
Fluoromisonidazole (
FMISO) was the first PET agent for
hypoxia imaging, and various radiolabeled
nitroimidazole derivatives such as [(18)F]
fluoroerythronitroimidazole (
FETNIM), [(18)F]1-α-D: -(2-deoxy-2-fluoroarabinofuranosyl)-2-nitroimidazole (FAZA), [(18)F]2-(2-nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)
acetamide (EF-5), and [(18)F]
fluoroetanidazole (FETA) have been developed successively. To overcome the high cost of
cyclotron installation, (68)Ga-labeled
nitroimidazole derivatives also have been developed. Another important
hypoxia imaging agent is (64)Cu-
diacetyl-bis(N (4)-methylthiosemicarbazone) ((64)Cu-ATSM), which can distribute in
cancer tissue rapidly due to high lipophilicity. However, its application is limited due to high cost of
radionuclide production. Although various
hypoxia imaging agents have been reported and tested,
hypoxia PET images still have to be improved, because of the low blood flow in hypoxic tissues and resulting low uptake of the agents.