title: Observer variability in the evaluation of multiple lumbar stenosis by routine MR--myelography and MRI.
abstract: METHODS
  Retrospective study.
  
  
  OBJECTIVE
  To determine whether magnetic resonance myelography (MRM) improves the evaluation of the severity of stenosis in patients with multilevel lumbar stenosis.
  
  
  BACKGROUND
  MRM shows a similar image as myelography in a noninvasive manner.
  
  
  METHODS
  One hundred patients over 50 years of age with multiple lumbar stenosis who were prospectively referred for MR imaging (MRI) with MRM were enrolled in the study. The most severe stenotic segment and the degree of stenosis of that segment, as assessed by the extent of remaining subarachnoidal space (1: normal to 50%; 2: over 50% but not a total blockage; 3: total blockage) were evaluated in a blinded manner by 2 observers. Conventional MRI (class A), MRM (class B), and MRI combined with MRM (class C) were evaluated independently and interobserver and intraobserver reliability were assessed.
  
  
  RESULTS
  In the selection of the most severe segment and degree of stenosis, for both observers, the consensus between class (B) and class (C), was higher than that of class (A) and class (C). The average kappa values for interobserver agreement in the selection of the most severe segment/assessing the degree of stenosis for classes (A), (B), and (C) were 0.649/0.727, 0.782/0.771, and 0.832/0.784, respectively. Intraobserver kappa values were also highest for class (B), followed by class (C), and then class (A). Observations were within the range of "almost perfect" (0.81< or =kappa< or =1), with the exception of the selection of the most severe segment in class (A) by one of the observers.
  
  
  CONCLUSIONS
  When employed in routine practice, MRM could be of value for improving observer reliability in the assessment of severity of stenosis in multiple lumbar stenosis.
authors.affiliation: Department of Orthopedic Surgery, Chung-Ang University, College of Medicine, Seoul, Korea. ksong70@cau.ac.kr
authors.forename: Kwang-Sup
authors.initials: KS
authors.lastname: Song
authors.forename: Eui-Chan
authors.initials: EC
authors.lastname: Jang
authors.forename: Ho-Joong
authors.initials: HJ
authors.lastname: Jung
authors.forename: Kyung-Woon
authors.initials: KW
authors.lastname: Kim
authors.forename: Hyeon
authors.initials: H
authors.lastname: Yu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007723:Korea; D008159:Lumbar Vertebrae / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009192:Myelography; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013130:Spinal Stenosis / Q000175:diagnosis*