title: Superior cervical ganglion mimicking retropharyngeal adenopathy in head and neck cancer patients: MRI features with anatomic, histologic, and surgical correlation.
abstract: BACKGROUND
  To describe the unique MRI findings of superior cervical ganglia (SCG) that may help differentiate them from retropharyngeal lymph nodes (RPLNs).
  
  
  METHODS
  A retrospective review of post-treatment NPC patients from 1999 to 2012 identified three patients previously irradiated for NPC that were suspected of having recurrent nodal disease in retropharyngeal lymph nodes during surveillance MRI. Subsequent surgical exploration revealed enlarged SCG only; no retropharyngeal nodal disease was found. A cadaveric head specimen was also imaged with a 3T MRI before and after dissection. In addition, SCG were also harvested from three cadaveric specimens and subjected to histologic analysis.
  
  
  RESULTS
  The SCG were found at the level of the C2 vertebral body, medial to the ICA. They were ovoid on axial images and fusiform and elongated with tapered margins in the coronal plane. T2-weighted (T2W) signal was hyperintense. No central elevated T1-weighted (T1W) signal was seen within the ganglia in non-fat-saturated sequences to suggest the presence of a fatty hilum. Enhancement after gadolinium was present. A central "black dot" was seen on axial T2W and post-contrast images in two of the three SCG demonstrated. Histology showed the central black line was comprised of venules and interlacing neurites within the central portion of the ganglion.
  
  
  CONCLUSIONS
  The SCG can be mistaken for enlarged RPLNs in post-treatment NPC patients. However, there are features which can help differentiate them from RPLNs, preventing unnecessary therapy. These imaging findings have not been previously described.
authors.affiliation: Department of Diagnostic Radiology, Tan Tock Seng Hospital, Basement 1, Podium Block, 11 Jalan Tan Tock Seng, Singapore, 308433, Republic of Singapore.
authors.forename: S C
authors.initials: SC
authors.lastname: Loke
authors.affiliation: Department of Diagnostic Radiology, Tan Tock Seng Hospital, Basement 1, Podium Block, 11 Jalan Tan Tock Seng, Singapore, 308433, Republic of Singapore.
authors.forename: A
authors.initials: A
authors.lastname: Karandikar
authors.affiliation: Department of Radiology, University of Brescia, Brescia, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Ravanelli
authors.affiliation: Department of Radiology, University of Brescia, Brescia, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Farina
authors.affiliation: Department of Diagnostic Radiology, Tan Tock Seng Hospital, Basement 1, Podium Block, 11 Jalan Tan Tock Seng, Singapore, 308433, Republic of Singapore. Julian_Goh@ttsh.com.sg.
authors.forename: J P N
authors.initials: JP
authors.lastname: Goh
authors.affiliation: Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Republic of Singapore.
authors.forename: E A
authors.initials: EA
authors.lastname: Ling
authors.affiliation: Department of Radiology, University of Brescia, Brescia, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Maroldi
authors.affiliation: Department of Radiology, Changi General Hospital, Singapore, Republic of Singapore.
authors.forename: T Y
authors.initials: TY
authors.lastname: Tan
mesh_terms: D002102:Cadaver; D003937:Diagnosis, Differential; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D000072281:Lymphadenopathy / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D010614:Pharynx; D012189:Retrospective Studies; D017783:Superior Cervical Ganglion / Q000000981:diagnostic imaging*
keywords: Head and neck; MRI; Retropharyngeal lymph node; Superior cervical ganglion