The patterns of nodal spread of nasopharyngeal carcinoma (NPC) have an important influence on treatment planning, but have not yet been fully addressed. We prospectively used MRI and FDG PET to document the patterns of nodal spread in NPC. One hundred and one patients with newly diagnosed NPC were studied with MRI and FDG PET. On MRI, nodes were considered as metastatic according to criteria regarding size, the presence of nodal necrosis, and extracapsular spread. FDG PET images were interpreted visually, and nodes were considered metastatic if they showed prominent FDG uptake against the background. Nodal metastases were found in 89 of our 101 patients. Analysis of the distributions of nodal metastases in these 89 patients showed that retropharyngeal nodes were less frequently involved than cervical nodes (82.0% vs 95.5%). The vast majority of cervical nodal metastases were to the internal jugular chain, including nodes at levels II, III, and IV, with decreasing incidences of 95.5%, 60.7%, and 34.8%, respectively. Level V nodal involvement was found in 27% of patients. Supraclavicular fossa nodal metastases were not uncommon and occurred in 22.5% of patients. Skip metastases in the lower-level nodes or supraclavicular fossa nodes occurred in 7.9% of patients. Mediastinal and abdominal metastatic adenopathy was present in 4.5% and 3.4% of patients, respectively, and was associated with advanced nodal metastasis in the supraclavicular fossa. Level VI (2.2%), level VII (1.1%), submandibular (2.2%), and parotid (3.4%) nodal metastases were uncommon and were always associated with advanced ipsilateral nodal metastases of the neck. We conclude that the combined use of FDG PET and MRI can comprehensively depict the pattern of nodal metastasis in NPC patients. Nodal metastases principally affected level II nodes, from which lymphatic spread extended down in an orderly manner to involve level III, level IV, and the supraclavicular fossa nodes, or extended posteriorly to involve level V nodes. The frequency of skip metastases was 7.9%. Distant spread to mediastinal or abdominal nodes was found in 3-5% of patients, usually in association with supraclavicular nodal metastases.

[18F]FDG PET is more sensitive than SS for detecting bone metastasis in endemic NPC at initial staging, whereas SS can be considered as supplementary in this setting.

[(18)F]FDG PET was superior to CT/MRI for detecting palpably occult neck metastasis of oral SCC. Because [(18)F]FDG PET could reduce the probability of occult neck metastasis to less than 15% in T1 to T3 tumors, it should be indicated for evaluation of these subpopulations.

In NPC patients, MRI appears to be superior to PET/CT for the assessment of locoregional invasion and retropharyngeal nodal metastasis. PET/CT is more accurate than MRI for determining cervical nodal metastasis and should be the better reference for the neck status. PET/CT has an acceptable diagnostic yield and a low false-positive rate for the detection of distant malignancy and can replace conventional work-up to this aim. PET/CT and head-and-neck MRI are suggested for the initial staging of NPC patients.