Over the years, external beam radiotherapy (EBRT) has been used in the treatment management
of many malignancies, including head and neck squamous cell carcinomas (HNSCC). Hypoxia
is a common feature in HNSCC. Hypoxic segments in HNSCC have proven to be more resistant
to radiotherapy. The ability to identify hypoxia using SPECT and PET tracers has been investigated
since the late 1970s. Nitroimidazole-based compounds labelled with positron emitters have been developed
to more specifically image hypoxia. This article reviews the current data from research
publications on18F–FMISO, 18F-FAZA, 18F-EF5 and 64Cu-ATSM.