title: Osteoradionecrosis of the upper cervical spine: MR imaging following radiotherapy for nasopharyngeal carcinoma.
abstract: OBJECTIVE
  To document the MRI appearances of radiation-induced abnormalities in the cervical spine following treatment for nasopharyngeal carcinoma (NPC).
  
  
  METHODS
  Patients with radiation-induced abnormalities in the upper cervical spine were identified from a retrospective analysis of reports from patients undergoing MRI follow-up. Imaging and clinical records of these patients were reviewed. Symmetrical distribution of abnormalities at C1 (anterior arch+/-adjacent aspect of the lateral masses) and C2 (dens+/-body especially with a characteristic horizontal rim of marrow preservation above the inferior endplate) were considered typical for osteoradionecrosis (ORN).
  
  
  RESULTS
  Abnormalities of C1/2 were identified in 9/884 (1%) patients. The MRI distribution of abnormalities was typical for ORN in four and atypical in five patients. Abnormal soft tissue was present in the atlantoaxial joint in eight patients, forming a florid mass in six. This soft tissue was in direct continuity with the posterior nasopharyngeal wall ulceration via the retropharyngeal region. The final clinical diagnosis was ORN in eight, five of whom had clinical factors which suggested infection could have played a contributory role, and osteomyelitis in one patient. All patients had undergone additional radiotherapy treatment comprising of brachytherapy (7), stereotactic radiotherapy (1) or radiotherapy boost (2) and three had undergone nasopharyngectomy.
  
  
  CONCLUSIONS
  ORN of the upper cervical spine following radiotherapy for NPC is more common than previously suspected and is seen in patients with additional treatment, especially brachytherapy. MRI features are often atypical and a contributory role of infection in the development of some cases of ORN is postulated.
authors.affiliation: Department of Diagnostic Radiology & Organ Imaging, Faculty of Medicine, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong S.A.R., China. king2015@cuhk.edu.hk
authors.forename: Ann D
authors.initials: AD
authors.lastname: King
authors.forename: James F
authors.initials: JF
authors.lastname: Griffith
authors.forename: Jill M
authors.initials: JM
authors.lastname: Abrigo
authors.forename: Sing-Fai
authors.initials: SF
authors.lastname: Leung
authors.forename: Fung-kwai
authors.initials: FK
authors.lastname: Yau
authors.forename: Gary M K
authors.initials: GM
authors.lastname: Tse
authors.forename: Anil T
authors.initials: AT
authors.lastname: Ahuja
mesh_terms: D000328:Adult; D002574:Cervical Vertebrae / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008536:Meglumine; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000532:radiotherapy*; D009942:Organometallic Compounds; D010025:Osteoradionecrosis / Q000473:pathology*; D019291:Skull Base / Q000473:pathology*
chemical_list: D003287:Contrast Media; D009942:Organometallic Compounds; D008536:Meglumine; D019786:Gadolinium DTPA; C072417:gadoterate meglumine