title: Erosion or normal variant? 4-year MRI follow-up of the wrists in healthy children.
abstract: BACKGROUND
  A large proportion of healthy children have wrist changes on MRI, namely carpal depressions, findings that have been described as pathological in children with juvenile idiopathic arthritis.
  
  
  OBJECTIVE
  We performed follow-up imaging in a cohort of healthy children to evaluate carpal surface depressions over time, focusing on the presence of overlying cartilage as a potential discriminator between normal variants and true erosions.
  
  
  METHODS
  74 of the initial cohort of 89 healthy children (83%) had a re-scan of their wrists using the same protocol, including coronal T1 and fat-saturated T2 sequences. A cartilage-selective sequence was added for this study. We registered number and location of bony depressions and presence of overlying cartilage.
  
  
  RESULTS
  The total number of carpal depressions increased by age group and over time; their location was unchanged in 370 of 487 (76%) carpal sites and 91 of 117 (78%) metacarpal sites. In total, 426 of the 1,087 (39.2%) bony depressions were covered by cartilage, with a decreasing percentage by age (P = 0.001).
  
  
  CONCLUSIONS
  Normal appearances during growth, such as bony depressions, should not be mistaken for pathology. There must be additional findings to support a diagnosis of disease. A cartilage sequence may add to the diagnostic image analysis.
authors.affiliation: Faculty of Health Sciences, University of Tromsø, 9037, Tromsø, Norway. derk.avenarius@unn.no.|Department of Radiology, University Hospital of North Norway, Tromsø, Norway. derk.avenarius@unn.no.
authors.forename: Derk F M
authors.initials: DF
authors.lastname: Avenarius
authors.affiliation: Department for Radiology and Intervention, Oslo University Hospital, Oslo, Norway.
authors.forename: Lil-Sofie
authors.initials: LS
authors.lastname: Ording Müller
authors.affiliation: Department of Radiology, Haukeland University Hospital, Bergen, Norway.|Department of Clinical Medicine K1, University of Bergen, Bergen, Norway.
authors.forename: Karen
authors.initials: K
authors.lastname: Rosendahl
mesh_terms: D000293:Adolescent; D000375:Aging / Q000473:pathology*; D002348:Carpal Bones / Q000000981:diagnostic imaging* / Q000473:pathology*; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000473:pathology*; D002648:Child; D015331:Cohort Studies; D003937:Diagnosis, Differential; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014953:Wrist
keywords: Cartilage; Children; Erosion; Magnetic resonance imaging; Normal variants; Wrist