title: Cartilage thickness of the knee joint in juvenile idiopathic arthritis: comparative assessment by ultrasonography and magnetic resonance imaging.
abstract: OBJECTIVE
  The functional disability experienced in juvenile idiopathic arthritis (JIA) is primarily caused by joint effusion, synovial membrane hypertrophy, and periarticular soft tissue edema, leading to the degeneration of the osteocartilaginous structures because of the inflammatory process in the synovium. The ability to visualize the inflammatory changes and hence the ensuing osteocartilaginous degeneration is, therefore, of great importance in pediatric rheumatology. Ultrasonography (US) has been validated as a tool for measuring cartilage thickness in healthy children and, previously, we have found good agreement with the measures obtained by magnetic resonance imaging (MRI). Our aim is to validate and compare US with MRI measurements of distal femoral cartilage thickness in the knee joint at the medial condyle, lateral condyle, and intercondylar spots in children with JIA, and to locate the best spot for imaging comparisons.
  
  
  METHODS
  One knee from each of 23 children with oligoarticular JIA were investigated by both MRI and US. Outcome measures of imaging procedures were distal femoral cartilage thickness.
  
  
  RESULTS
  We found a high level of agreement between MRI and US measurements of mean cartilage thickness, and Rho values between modalities were high (between 0.70 and 0.86, p < 0.05 for all). We found a thinner cartilage thickness at the medial condyle in comparison to the other investigated points. Evaluation of anatomical landmarks for optimal measurement of cartilage thickness was found to be the intercondylar spot, which was easier to locate in addition to a smaller variance around the mean for that anatomical measuring point.
  
  
  CONCLUSIONS
  US measurements of distal femoral cartilage thickness are highly correlated to MRI measurements. The intercondylar notch of the distal femoral cartilage may be the best anatomical point for cartilage thickness measurements of the knee. US is a reliant and nonexpensive, non-invasive modality for visualization of childhood femoral cartilage.
authors.affiliation: From the Department of Pediatrics, Department of Radiology, and MRI Centre, Aarhus University Hospital Skejby, Aarhus, Denmark.D.Ø. Pradsgaard, MD; A.H. Spannow, MD, PhD; C. Heuck, MD, PhD; T. Herlin, MD, DMSc, Department of Pediatrics; B. Fiirgaard, MD, Department of Radiology, MRI Centre, Aarhus University Hospital Skejby. pradsgaard@ki.au.dk.
authors.forename: Dan Østergaard
authors.initials: DØ
authors.lastname: Pradsgaard
authors.affiliation: From the Department of Pediatrics, Department of Radiology, and MRI Centre, Aarhus University Hospital Skejby, Aarhus, Denmark.D.Ø. Pradsgaard, MD; A.H. Spannow, MD, PhD; C. Heuck, MD, PhD; T. Herlin, MD, DMSc, Department of Pediatrics; B. Fiirgaard, MD, Department of Radiology, MRI Centre, Aarhus University Hospital Skejby.
authors.forename: Bente
authors.initials: B
authors.lastname: Fiirgaard
authors.affiliation: From the Department of Pediatrics, Department of Radiology, and MRI Centre, Aarhus University Hospital Skejby, Aarhus, Denmark.D.Ø. Pradsgaard, MD; A.H. Spannow, MD, PhD; C. Heuck, MD, PhD; T. Herlin, MD, DMSc, Department of Pediatrics; B. Fiirgaard, MD, Department of Radiology, MRI Centre, Aarhus University Hospital Skejby.
authors.forename: Anne Helen
authors.initials: AH
authors.lastname: Spannow
authors.affiliation: From the Department of Pediatrics, Department of Radiology, and MRI Centre, Aarhus University Hospital Skejby, Aarhus, Denmark.D.Ø. Pradsgaard, MD; A.H. Spannow, MD, PhD; C. Heuck, MD, PhD; T. Herlin, MD, DMSc, Department of Pediatrics; B. Fiirgaard, MD, Department of Radiology, MRI Centre, Aarhus University Hospital Skejby.
authors.forename: Carsten
authors.initials: C
authors.lastname: Heuck
authors.affiliation: From the Department of Pediatrics, Department of Radiology, and MRI Centre, Aarhus University Hospital Skejby, Aarhus, Denmark.D.Ø. Pradsgaard, MD; A.H. Spannow, MD, PhD; C. Heuck, MD, PhD; T. Herlin, MD, DMSc, Department of Pediatrics; B. Fiirgaard, MD, Department of Radiology, MRI Centre, Aarhus University Hospital Skejby.
authors.forename: Troels
authors.initials: T
authors.lastname: Herlin
mesh_terms: D000293:Adolescent; D001171:Arthritis, Juvenile / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000473:pathology; D002358:Cartilage, Articular / Q000000981:diagnostic imaging* / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D013583:Synovial Membrane; D014463:Ultrasonography
keywords: CARTILAGE; JUVENILE IDIOPATHIC ARTHRITIS; MAGNETIC RESONANCE IMAGING; ULTRASONOGRAPHY