Update on 18F-fluorodeoxyglucose/positron emission tomography and positron emission tomography/computed tomography imaging of squamous head and neck cancers.

This article summarizes the recent literature in (18)F-fluorodeoxyglucose/positron emission tomography (FDG-PET) imaging of head and neck cancers and extends the previous review in this area by Schöder and Yeung in the July 2004 issue of Seminars in Nuclear Medicine. Positron emission tomography/computed tomography (PET-CT) imaging is now used widely but has not been adequately evaluated for head and neck cancer. Its accuracy in initial staging is better than CT but may be similar to magnetic resonance imaging. It is not sufficiently accurate in the N0 neck to rule out nodal metastases but may be appropriate if sentinel node mapping is performed in patients with PET studies showing no nodal disease. PET imaging is beginning to be used in radiotherapy treatment planning, where it makes a significant difference by identifying malignant normal size nodes, extent of viable tumor, and distant disease. PET continues to be useful in carcinoma of unknown primary in identification of the primary site. Overall success is around 27% after all other modalities have failed. FDG-PET is being used frequently to assess response to therapy and for surveillance thereafter. The major controversy is when to image after radiotherapy or combined chemo-radiotherapy. One month seems to be too early. The ideal time seems to be 3 to 4 months to avoid both false-positive and false-negative studies. The growing use of PET-CT studies in head and neck cancer will certainly make a significant difference in the treatment and outcome in this disease.