title: MRI of a syrinx: is contrast material always necessary?
abstract: OBJECTIVE
  The workup of a syrinx often includes contrast-enhanced MRI to exclude the presence of an underlying mass. The diagnostic yield of performing these additional contrast-enhanced sequences is not well defined in the literature. We hypothesized that T2-weighted imaging alone could reliably exclude the presence of a syrinx-associated mass without the need for contrast-enhanced imaging sequences in all cases.
  
  
  METHODS
  Two independent readers retrospectively analyzed contrast-enhanced MRI studies of 87 consecutive patients with syringes. The presence or absence of an associated spinal cord mass was determined using only T2-weighted imaging. The imaging features considered positive for a possible syrinx-associated lesion on T2-weighted imaging were syrinx nodularity, syrinx septations, and a spinal cord signal intensity abnormality or a mass separate from the syrinx. The size of the syrinx was also recorded. Using contrast-enhanced sequences as the reference standard, statistical analysis was performed to determine the accuracy of T2-weighted imaging in detecting a syrinx-associated mass.
  
  
  RESULTS
  Of the 87 cases of syrinx, there were 23 mass lesions, 11 Chiari malformations, three spinal cord contusions, and 50 idiopathic syringes. Using T2-weighted imaging alone, readers detected no findings suspicious for a syrinx-associated mass in 55 cases and detected findings suspicious for a mass in 32 of 87 cases. Reader sensitivity for an underlying mass lesion was 100%; specificity, 86%; positive predictive value, 72%; and negative predictive value, 100%. Interreader agreement was excellent (κ = 0.88). Syrinx size showed a positive correlation with the presence of a mass lesion (p < 0.0001).
  
  
  CONCLUSIONS
  T2-weighted imaging alone appears to have a high sensitivity and high negative predictive value in evaluating for a syrinx-associated mass, and contrast-enhanced imaging may not be required for the workup of a syrinx.
authors.affiliation: 1 Department of Radiology, Division of Neuroradiology, Massachusetts General Hospital, 55 Fruit St, Gray 2, Rm 273A, Boston, MA 02114.
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Timpone
authors.forename: Sohil H
authors.initials: SH
authors.lastname: Patel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013595:Syringomyelia / Q000175:diagnosis*
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA
keywords: contrast-enhanced follow-up MRI; cystic intramedullary mass; diagnostic yield; syringohydromyelia; syrinx