title: Discordant inflammatory changes in the apophyseal and sacroiliac joints: serial observations in enthesitis-related arthritis.
abstract: OBJECTIVE
  To determine the extent to which inflammation of the sacroiliac joints (SIJs) and apophyseal joints (AJs) changes concordantly after treatment in enthesitis-related arthritis (ERA).
  
  
  METHODS
  A retrospective study was performed with institutional review board approval. 31 young patients with ERA who had been scanned between March 2009 and November 2014 were included. All patients had post-contrast imaging of the SIJs and lumbar spine and short tau inversion-recovery (STIR) images of the SIJs. The severity of sacroiliitis was scored using a modification of an established technique, and inflammation of the AJs was evaluated using a recently described grading system. The changes in SIJ and AJ scores after treatment were classified as either concordant or discordant, and the proportion of scan pairs in these groups was recorded. In addition, the correlation between change in SIJ STIR score (Δnfla) and change in AJ score (ΔAJ) was assessed using Spearman's correlation coefficient.
  
  
  RESULTS
  Of a total of 43 scan pairs, the changes in inflammation were concordant in 16 scan pairs and discordant in 27 scan pairs. There was no significant correlation between Δnfla and ΔAJ (R = 0.14, p = 0.37).
  
  
  CONCLUSIONS
  Inflammatory changes in the SIJs and AJs are often discordant. This may be a reason why patients experience ongoing back pain despite apparent improvement in one or the other site.
  
  
  CONCLUSIONS
  Inflammation may behave differently at different anatomical sites. The SIJs and AJs should both be imaged in patients with ERA with back pain.
authors.affiliation: 1 Centre for Medical Imaging, University College London, London, UK.
authors.forename: Timothy J P
authors.initials: TJ
authors.lastname: Bray
authors.affiliation: 1 Centre for Medical Imaging, University College London, London, UK.
authors.forename: Thomas
authors.initials: T
authors.lastname: Amies
authors.affiliation: 1 Centre for Medical Imaging, University College London, London, UK.
authors.forename: Kanimozhi
authors.initials: K
authors.lastname: Vendhan
authors.affiliation: 1 Centre for Medical Imaging, University College London, London, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Humphries
authors.affiliation: 2 Arthritis UK Centre for Adolescent Rheumatology, University College London, London, UK.
authors.forename: Debajit
authors.initials: D
authors.lastname: Sen
authors.affiliation: 2 Arthritis UK Centre for Adolescent Rheumatology, University College London, London, UK.
authors.forename: Yiannis
authors.initials: Y
authors.lastname: Ioannou
authors.affiliation: 1 Centre for Medical Imaging, University College London, London, UK.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Hall-Craggs
mesh_terms: D000293:Adolescent; D018501:Antirheumatic Agents / Q000627:therapeutic use; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D015588:Observer Variation; D012189:Retrospective Studies; D012446:Sacroiliac Joint / Q000473:pathology*; D058566:Sacroiliitis / Q000188:drug therapy / Q000473:pathology*; D055815:Young Adult
chemical_list: D018501:Antirheumatic Agents