title: MR imaging and CT in osteoarthritis of the lumbar facet joints.
abstract: OBJECTIVE
  To test the agreement between MR imaging and CT in the assessment of osteoarthritis of the lumbar facet joints, and thus to provide data about the need for an additional CT scan in the presence of an MR examination.
  
  
  METHODS
  Using a four-point scale, two musculoskeletal radiologists independently graded the severity of osteoarthritis of 308 lumbar facet joints on axial T2-weighted and on sagittal T1- and T2-weighted turbo-spin-echo images and separately on the corresponding axial CT scans. Kappa statistics and percentage agreement were calculated.
  
  
  RESULTS
  The weighted kappa coefficients for MR imaging versus CT were 0.61 and 0.49 for readers 1 and 2, respectively. The weighted kappa coefficients for interobserver agreement were 0.41 for MR imaging and 0.60 for CT, respectively. There was agreement within one grade between MR and CT images in 95% of cases for reader 1, and in 97% of cases for reader 2.
  
  
  CONCLUSIONS
  With regard to osteoarthritis of the lumbar facet joints there is moderate to good agreement between MR imaging and CT. When differences of one grade are disregarded agreement is even excellent. Therefore, in the presence of an MR examination CT is not required for the assessment of facet joint degeneration.
authors.affiliation: Department of Radiology, Orthopedic University Hospital Balgrist, Zurich, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Weishaupt
authors.forename: M
authors.initials: M
authors.lastname: Zanetti
authors.forename: N
authors.initials: N
authors.lastname: Boos
authors.forename: J
authors.initials: J
authors.lastname: Hodler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D010003:Osteoarthritis / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed