Introduction: We performed this study to explore the diagnostic accuracies and cutoff values of contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI) for the detection and diagnosis of metastatic retropharyngeal lymph nodes (RLNs) in patients with nasopharyngeal carcinoma (NPC).
Methods: One hundred and twenty-eight patients with a total of 159 RLNs were included in the study. The sizes of maximal and minimal axial diameters of each node on both contrast-enhanced CT and MRI images were measured. The characteristics of the RLNs (malignant or benign), as well as the survival of patients, were classified based on the results of follow-up MRI.
Results: RLN size cutoffs of 4– 11 mm for minimal axial diameter were used. We found that MRI showed higher sensitivity while CT demonstrated higher specificity. The reasonable criterion for the diagnosis of metastatic RLNs in MRI was a minimal axial diameter of ≥ 6 mm, which yielded a sensitivity, specificity and diagnostic odds ratio (DOR) of 0.71, 0.82 and 10.88.
Conclusion: The radiologic criteria that should be used for the assessment of RLN metastases in NPC patients are nodes with a minimal axial diameter of ≥ 6 mm on MR images.
Keywords: retropharyngeal lymph node, metastasis, nasopharyngeal carcinoma, cutoff, MRI