title: Reliability of change in lumbar MRI findings over time in patients with and without disc prosthesis--comparing two different image evaluation methods.
abstract: OBJECTIVE
  To assess the reliability of change in lumbar magnetic resonance imaging (MRI) findings evaluated retrospectively by direct comparison of images and by non-comparison.
  
  
  METHODS
  Pre-treatment and 2-year follow-up MRI was performed in 126 patients randomized to disc prosthesis surgery or non-surgical treatment. Two experienced radiologists independently evaluated progress and regress for Modic changes, disc findings, and facet arthropathy (FA) at L3/L4, L4/L5, and L5/S1, both by non-comparison and by comparison of initial and follow-up images. FA was evaluated at all levels, and other findings at non-operated levels. We calculated prevalence- and bias-adjusted kappa (PABAK) values for interobserver agreement. The impact of an adjacent prosthesis (which causes artefacts) and image evaluation method on PABAK was assessed using generalized estimating equations.
  
  
  RESULTS
  Image comparison indicated good interobserver agreement on progress and regress (PABAK 0.63-1.00) for Modic changes, posterior high-intensity zone, disc height, and disc contour at L3-S1 and for nucleus pulposus signal and FA at L3/L4; and moderate interobserver agreement (PABAK 0.46-0.59) on decreasing nucleus signal and increasing FA at L4-S1. Image comparison indicated lower (but fair) interobserver agreement (PABAK 0.29) only for increasing FA at L5/S1 in patients with prosthesis in L4/L5 and/or L5/S1. An adjacent prosthesis had no overall impact on PABAK values (p ≥ 0.22). Comparison yielded higher PABAK values than non-comparison (p < 0.001).
  
  
  CONCLUSIONS
  Regarding changes in lumbar MRI findings over time, comparison of images can provide moderate or good interobserver agreement, and better agreement than non-comparison. An adjacent prosthesis may not reduce agreement on change for most findings.
authors.affiliation: Department of Radiology, Haukeland University Hospital, Jonas Liesvei 65, 5021, Bergen, Norway. linda.berg@kir.uib.no
authors.forename: Linda
authors.initials: L
authors.lastname: Berg
authors.forename: Oivind
authors.initials: O
authors.lastname: Gjertsen
authors.forename: Christian
authors.initials: C
authors.lastname: Hellum
authors.forename: Gesche
authors.initials: G
authors.lastname: Neckelmann
authors.forename: Lars G
authors.initials: LG
authors.lastname: Johnsen
authors.forename: Geir E
authors.initials: GE
authors.lastname: Eide
authors.forename: Ansgar
authors.initials: A
authors.lastname: Espeland
mesh_terms: D000328:Adult; D000465:Algorithms; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D055959:Intervertebral Disc Degeneration / Q000473:pathology* / Q000628:therapy*; D008137:Longitudinal Studies; D008159:Lumbar Vertebrae / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D059145:Total Disc Replacement; D016896:Treatment Outcome