Clinical Usefulness of [18F]FDG PET-CT and CT/MRI for Detecting Nodal Metastasis in Patients with Hypopharyngeal Squamous Cell Carcinoma

Background and Purpose. The aim of this study was to investigate whether pretreatment imaging modalities, including [18F] fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) and CT/magnetic resonance imaging (MRI) are helpful for the selection of patient groups requiring contralateral neck dissection in patients with hypopharyngeal squamous cell carcinoma (SCC). Methods. A total of 72 consecutive patients with histologically proven hypopharyngeal SCC who underwent both PET-CT and CT/MRI preoperatively were recruited. To assess the diagnostic accuracy of each imaging modality, the neck was divided into levels based on the imaging-based nodal classification, and the histopathologic results of the surgical specimen were used as a standard reference. Results. Fifty-one (70.8 %) of the 72 patients had neck metastasis, and 12 (26.7 %) had contralateral metastatic nodes. The sensitivities of PET-CT and CT/MRI for detecting nodal metastasis in the contralateral neck were significantly lower than those in the ipsilateral neck (60.0 and 53.3 vs. 89.1 and 84.8 %, respectively; p<0.001). Among the patients who underwent bilateral neck dissection (n = 45), three (13.0 %) of the 23 patients with a palpably negative neck on the ipsilateral side showed occult contralateral lymph node metastasis, while none of the 11 patients without ipsilateral metastatic nodes on imaging studies had contralateral neck metastasis. Conclusions. With accurate assessment of ipsilateral neck metastasis in hypopharyngeal SCC patients, PET-CT and CT/MRI may be helpful in identifying patients at high risk of contralateral neck metastasis. Elective contralateral neck treatment is not necessary in hypopharyngeal SCC patients who do not show evidence of ipsilateral neck metastasis on preoperative imaging studies.