title: MRI assessment of bone marrow in children with juvenile idiopathic arthritis: intra- and inter-observer variability.
abstract: BACKGROUND
  Bone marrow oedema (BMO) is included in MRI-based scoring systems of disease activity in adults with rheumatoid arthritis. Similar systems in juvenile idiopathic arthritis (JIA) are lacking.
  
  
  OBJECTIVE
  To assess the reproducibility in a multi-centre setting of an MRI BMO scoring system in children with JIA.
  
  
  METHODS
  Seventy-six wrist MRIs were read twice, independently, by two experienced paediatric radiologists. BMO was defined as ill-defined lesions within the trabecular bone, returning high and low signal on T2- and T1-weighted images respectively, with or without contrast enhancement. BMO extension was scored for each of 14 bones at the wrist from 0 (none) to 3 (extensive).
  
  
  RESULTS
  The intra-observer agreement was moderate to excellent, with weighted kappa ranging from 0.85 to 1.0 and 0.49 to 1.0 (readers 1 and 2 respectively), while the inter-observer agreement ranged from 0.41 to 0.79. The intra- and inter-observer intraclass correlation coefficients were excellent and satisfactory, respectively.
  
  
  CONCLUSIONS
  The scoring system was reliable and may be used for grading bone marrow abnormality in JIA. The relatively large variability in aggregate scores, particularly between readers, underscores the need for thorough standardisation.
authors.affiliation: Department of Radiology, Ospedale Pediatrico Bambino Gesù, Piazza S Onofrio 4, 00165 Rome, Italy. laura.tanturri@opbg.net
authors.forename: Laura
authors.initials: L
authors.lastname: Tanturri de Horatio
authors.forename: Maria Beatrice
authors.initials: MB
authors.lastname: Damasio
authors.forename: Domenico
authors.initials: D
authors.lastname: Barbuti
authors.forename: Claudia
authors.initials: C
authors.lastname: Bracaglia
authors.forename: Karen
authors.initials: K
authors.lastname: Lambot-Juhan
authors.forename: Peter
authors.initials: P
authors.lastname: Boavida
authors.forename: Lil-Sofie
authors.initials: LS
authors.lastname: Ording Müller
authors.forename: Clara
authors.initials: C
authors.lastname: Malattia
authors.forename: Lucilla
authors.initials: L
authors.lastname: Ravà
authors.forename: Karen
authors.initials: K
authors.lastname: Rosendahl
authors.forename: Paolo
authors.initials: P
authors.lastname: Tomà
mesh_terms: D000293:Adolescent; D001171:Arthritis, Juvenile / Q000150:complications* / Q000473:pathology*; D001853:Bone Marrow / Q000473:pathology; D001855:Bone Marrow Diseases / Q000150:complications* / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D004487:Edema / Q000150:complications* / Q000473:pathology*; D005260:Female; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity