title: [Radiologic criteria of MRI in diagnosing retropharyngeal lymph nodal metastasis of nasopharyngeal carcinoma].
abstract: OBJECTIVE
  To explore the reasonable radiologic criteria of retropharyngeal lymph nodal (RLN) metastasis of nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  275 patients with newly diagnosed NPC were enrolled. All patients underwent Magnetic resonance imaging (MRI) before treatment to measure the sizes of maximal and minimal axial diameters of each node. Determination of malignancy was based on the results of MRI follow-up. Receiver operating characteristic (ROC) curve was used to determine the optimal axial diameter and cutoff size criterion of RLN metastasis.
  
  
  RESULTS
  Among the 275 patients, a total number of 468 RLNs were assessed. 240 positive and 228 negative nodes were later confirmed by the MRI follow-up. The mean sizes of minimal and maximal axial diameters for positive nodes were significantly higher than those for negative nodes (9.9 mm +/- 4.8 mm vs 3.3 mm +/- 1.2 mm, 12.9 mm +/- 5.8 mm vs 5.7 mm +/- 2.0 mm, all P < 0.01). The reasonable criterion for diagnosing RLN metastasis was the minimal axial diameter of > or = 6 mm. The sensitivity, specificity and accuracy of this criterion were 84.1%, 94.3% and 89.1%, respectively. There were 3 nodes whose minimal axial diameter was < 6 mm in 50 RLNs with central necrosis. Central necrosis combined with the minimal axial diameter criteria slightly increased the sensitivity at a stable specificity.
  
  
  CONCLUSIONS
  The reasonable radiologic criteria for assessing RLN metastasis of NPC are: (1) node with a minimal axial diameter > or = 6 mm; and (2) any node with central necrosis.
authors.affiliation: State Key Laboratory of Oncology in Southern China, Cancer Center, Sun Yat-sen University, Guangzhou 510060, China.
authors.forename: Guo-yi
authors.initials: GY
authors.lastname: Zhang
authors.forename: Li-zhi
authors.initials: LZ
authors.lastname: Liu
authors.forename: Wei-han
authors.initials: WH
authors.lastname: Hu
authors.forename: Chong
authors.initials: C
authors.lastname: Zhao
authors.forename: Yuan-hong
authors.initials: YH
authors.lastname: Gao
authors.forename: Xue-wen
authors.initials: XW
authors.lastname: Liu
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000473:pathology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity