Additional diagnostic value of 18F-FDG PET-CT in detecting retropharyngeal nodal metastases

Objective: This study investigated whether preoperative 18fluorine-fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) scanning improved the diagnosis of retropharyngeal lymph node (RPLN) metastasis in patients with head and neck squamous cell carcinoma (HNSCC) relative to conventional imaging alone. Study Design: Case series with chart review. Setting: University hospital cancer center. Subjects and Methods: Sixty-three patients with HNSCC underwent RPLN dissection in accordance with our indications and were subsequently divided into two groups: CT/magnetic resonance imaging (MRI) only (group A, n = 33) and CT/MRI with PET-CT (group B, n = 30). The preoperative radiological findings of each group were compared with the RPLN histopathologic findings, which served as the standard of reference. Results: RPLN metastasis was confirmed histopathologically in 17 of 63 patients (27.0%): eight from group A and nine from group B. With the additional use of PET-CT in group B, the sensitivity (88.9%), specificity (85.7%), and accuracy (86.7%) were higher than the respective values in group A (62.5%, 60.0%, and 60.6%). The positive and negative predictive values for group B (72.7% and 94.7%, respectively) were also higher than those for group A (33.3% and 83.3%, respectively). False-positive results were obtained in 10 patients from group A and three patients from B; false-negative findings occurred in three patients from group A and one patient from group B. The predictive power of the radiological findings was statistically significant in group B (P = 0.0017), with an odds ratio of 47.987 (95% confidence interval, 4.3-535.0). Conclusion: 18F-FDG PET-CT, when used in combination with CT/MRI, increases diagnostic efficacy in the detection of RPLN metastases and may therefore be useful in screening high-risk patients.