Tumor Hypoxia Imaging Agents in Nuclear Medicine

Hypoxia is due to imbalance in oxygen supply and oxygen demand compromising biological functions of cells. Since tumor hypoxia results in angiogenesis, apoptosis, metastasis, tumor aggressiveness and treatment failure, in vivo measurement is required. Nuclear imaging can provide information about tissue oxygen levels. 2-nitroimidazole containing compounds selectively accumulate in hypoxic cells. They have been radiolabeled with 18F, 123/124I, and 99mTc and used in clinical trial stages using PET and SPECT techniques. 62/64Cu-ATSM is a non-imidazole imaging agent, which is trapped in hypoxic cells. There is a great interest in the development of 99mTc-labeled 2-nitroimidazole compounds. Though novel compounds based on molecular mechanisms of hypoxia would be developed in future.