Positron emission tomography (PET) in the staging of head neck cancer: comparison between PET and CT.

Standard pre-treatment clinical staging (TNM) of head and neck squamous cell carcinoma includes clinical and instrumental objective examination of primary tumour and of the cervical lymph nodes (inspection, palpation of neck, panendoscopy, biopsy of tumour, fine needle aspiration of nodes) and computed tomography or magnetic resonance imaging. Albeit, this procedure presents diagnostic limitations in the identification of approximately 1/3 of T1, of small sized nodes and in the diagnosis of metastases. Positron emission tomography-fluorodesoxy-glucose imaging, in the diagnostic workup of these cases, appears to offer an important contribution, however, its use is limited due to poor availability of this equipment and the high cost of the examination. In the present study, a comparison is made of results of standard clinical staging and positron emission tomography-fluorodesoxy-glucose in 22 patients with head and neck carcinoma prior to surgical treatment, with the results of pathological staging (pTNM) carried out on surgical specimens. In the staging of the tumour, computed tomography shows a sensitivity of 71% and positron emission tomography of 81%. In the staging of nodes, computed tomography imaging shows a sensitivity of 73%, a specificity of 57% and an accuracy of 68%, whereas positron emission tomography shows a sensitivity of 93%, a specificity of 100% and an accuracy of 95%. Furthermore, positron emission tomography identified 1/5 occult tumours and one tumour revealed at objective endoscopic examination, but not by computed tomography. The risk of occult nodes following positron emission tomography was found to be 7%. Overall, these results are in keeping with those reported in the literature, thus confirming the usefulness of positron emission tomography-fluorodesoxy-glucose in identifying occult tumours and nodes, in which computed tomography appears to be limited. Indications of positron emission tomography-fluorodesoxy-glucose may play a role in the choice of therapeutic options for the clinically N0 neck.