Retropharyngeal Node Metastasis in Nasopharyngeal Carcinoma

Abstract

Objective: PET/CT has been proposed to enhance pretreatment evaluation of cervical nodal status in patients with nasopharyngeal carcinoma (NPC). The purpose of this study was to compare PET/CT and enhanced CT in the detection of retropharyngeal lymph node (RLN) metastasis in NPC, and to ascertain the factors affecting its diagnostic performance. Method: From 2007 to 2008, 33 patients with newly diagnosed NPC were prospectively studied. All patients underwent an enhanced CT scan and FDG-PET/CT. Results: The detection rate of RLN metastasis on PET/CT was significantly lower than that on enhanced CT (36.4% vs 75.8%), Pmax of RLNs was positively correlated with the minimal axial diameter (r=0.803), P < 5 mm, 9% for those 5 to 10 mm, and 73% for those ≥1 cm. The detection rate of PET/CT at C1 level was significant lower than that at C2 level (22% vs 67%, P = .035), suggesting that RLNs in close proximity to the primary tumor hindered the recognition by PET/CT. Conclusion: PET/CT is inferior to enhanced CT in detecting RLN metastasis in NPC, especially in lymph nodes with a diameter less than 1 cm or in close proximity to the primary tumor. Using enhanced CT in PET/CT is complementary in delineating the RLN metastasis in patients with NPC.