title: [Value of Radiation Therapy Oncology Group guidelines based on MR imaging in diagnosing lymph node metastasis of nasopharyngeal carcinoma].
abstract: OBJECTIVE
  Radiation Therapy Oncology Group (RTOG) and other major cooperative groups endorse the consensus guidelines for the delineation of the node levels in stage N0 cases. But it is unclear if these guidelines can be extrapolated to N+ cases. This study was to explore the value of RTOG guidelines in delineating cervical target volumes for nasopharyngeal carcinoma (NPC) patients with lymph node metastasis.
  
  
  METHODS
  Conventional magnetic resonance imaging (MRI) of the nasopharynx, including plain and contrast enhanced sequences, was performed on 254 naive NPC patients. The lymph nodes were divided into six cervical levels plus retropharyngeal nodes (RN) according to RTOG guidelines proposed in 2003.
  
  
  RESULTS
  Anatomic boundaries of node levels were observed clearly on MRI. Of the 254 patients, 107 (42.1%) had obvious lymph node necrosis, 78 (30.7%) had extracapsular nodal spread, four (1.6%) had skipped metastasis. The levels of lymph node metastases in 51 (20.1%) patients were beyond RTOG guidelines, 42 of which were above cranial level IIb, six were behind the anterior edge of the trapezius muscle, and 23 were below the caudal of level IV; 20 patients had two regions of lymph node metastases beyond RTOG guidelines. No patient only with lymph node metastasis beyond RTOG guidelines was found.
  
  
  CONCLUSIONS
  MRI is feasible to diagnose cervical node metastasis with RTOG guidelines. The boundaries of node levels should be enlarged rationally when delineating target volumes for the N+ NPC patients according to RTOG guidelines.
authors.affiliation: Department of Radiology, The Second Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, China.
authors.forename: Zhong-Xiang
authors.initials: ZX
authors.lastname: Ding
authors.forename: Bi-Ling
authors.initials: BL
authors.lastname: Liang
authors.forename: Jun
authors.initials: J
authors.lastname: Shen
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.forename: Bang-Kun
authors.initials: BK
authors.lastname: Xie
authors.forename: Jian-Hua
authors.initials: JH
authors.lastname: Yuan
mesh_terms: D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis / Q000175:diagnosis* / Q000473:pathology; D008279:Magnetic Resonance Imaging / Q000379:methods / Q000592:standards; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000473:pathology*; D009333:Neck; D009367:Neoplasm Staging; D017410:Practice Guidelines as Topic