ABSTRACTIn recent years the use of 18F-Fluorodeoxyglucose (FDG) Positron Emission Tomography for the evaluation of head and neck cancers has increased, mainly with the introduction of fused PET/CT imaging. This new imaging modality combines the metabolic imaging of FDG-PET with the precise anatomical localization of lesions on CT images, and thereby reduces the limitations of PET and CT scannings alone. The indications for fused PET/CT imaging are staging and evaluating primary head and neck cancers, including thyroid cancer, localizing unknown primary tumours, finding nodal metastases in patients staged with N0 necks, diagnosing second primary tumours, evaluating treatment response and finding residual and recurrent cancer. This article looks primarily at recent literature on PET/CT. Methods: Medline search using search terms “’PET-CT and ’head and neck cancer’” and “PET and ‘head and neck cancer’” combined with ‘unknown primary’, ‘N0 neck’, ‘second primary’, ‘thyroid cancer’, ‘residual or recurrent cancer’, ‘staging’, general google searches and browsing relevant journals. Results: PET/CT does not contribute to the classification of tumours that are diagnosed by conventional modalities. Unknown primary tumours are identified with a 33-60% accuracy. The primary indications for PET/CT in thyroid cancer are anaplastic and medullary carcinomas, the value in differentiated thyroid carcinomas is limited. PET/CT usefulness in N0 necks is limited. More studies on PET/CT are needed to determine the usefulness in detecting second primary tumours. PET/CT identifies recurrent and residual cancer with 40-96% sensitivity. The main limitations of PET/CT are reduced detection of small lesions and various artefacts.
Keywords: PET/CT, FDG-PET, head and neck cancer, staging, unknown primary, thyroid cancer, N0 neck, second primary, residual/recurrent cancer.