Is there a need for positron emission tomography imaging to stage the N0 neck in T1-T2 squamous cell carcinoma of the oral cavity or oropharynx?

Objectives: We assess whether negative findings on computed tomography (CT), magnetic resonance imaging (MRI), and/or ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸FDG-PET) may contribute to the decision-making process of elective neck dissection (eND) in patients with squamous cell carcinoma of the oral cavity or the oropharynx (oSCC) staged cT1-T2 cN0 cM0. Methods: We interpreted CT, MRI, and ¹⁸FDG-PET images separately, after combining the data of CT with those of ¹⁸FDG-PET and the data of MRI with those of ¹⁸FDG-PET. Each set of results was then compared with the histopathologic results of ipsilateral or bilateral eND in a prospective, blinded study. Results: The histopathologic examination of 594 lymph nodes revealed 4 metastases less than 4 mm in diameter and 3 micrometastases (less than 2 mm) in 6 of 17 patients. On CT, MRI, and ¹⁸FDG-PET, respectively, 5, 5, and 0 cases were true-malignant (true positives) and 4, 10, and 1 cases were false-malignant (false positives). The accuracy was not enhanced by fusing CT with ¹⁸FDG-PET or MRI with ¹⁸FDG-PET. Conclusions: The detectability threshold of occult metastases appears to be below the spatial and contrast resolution of CT, MRI, and ¹⁸FDG-PET. The decision for eND in patients with cT1-T2 cN0 cM0 oSCC cannot be based upon cross-sectional imaging at the resolutions currently available.