Current status of FDG-PET for head and neck cancer.

18-FDG-PET has utility for the identification of the unknown primary head and neck squamous carcinoma, distant metastases or second primary carcinomas, and recurrent HNSCC in the post-treatment setting. PET has a high negative predictive value in the detection of recurrent HNSCC. Standardized uptake values have demonstrated prognostic value. Limitations of PET include a lower utility for identifying occult nodal metastases and false positive readings from inflammation, infection, muscle activity, and radiation effect. Novel radioactive tracers may enable PET to identify sites of DNA replication, protein metabolism, and hypoxia.