title: A diffusion-based quantification technique for assessment of sacroiliitis in adolescents with enthesitis-related arthritis.
abstract: OBJECTIVE
  To investigate the use of a quantitative diffusion-weighted imaging (DWI) tool for measuring inflammation of the sacroiliac joints (SIJs) in enthesitis-related arthritis (ERA).
  
  
  METHODS
  A retrospective study was performed with institutional review board approval. Subjects were adolescents who had undergone MRI of the SIJs since January 2010. 10 patients with a clinical diagnosis of ERA and 10 controls with a clinical diagnosis of mechanical back pain were assessed. Axial T1 weighted, short tau inversion recovery (STIR) and DWI (b-values 0, 50, 100, 300 and 600 mm(2) s(-1)) images were acquired. Apparent diffusion coefficient (ADC) maps were generated using a monoexponential fit. On each of four slices, two to three linear regions-of-interest were placed on each joint. Normalized ADC (nADC) values were defined as joint ADC divided by a reference ADC derived from normal sacral bone. STIR images were scored using a modification of an established technique. The correlation between nADC values and STIR scores was evaluated using Spearman's rank correlation.
  
  
  RESULTS
  Mean nADC values were significantly higher in cases than in controls (p = 0.0015). There was a strong correlation between STIR scores and nADC values (R = 0.85).
  
  
  CONCLUSIONS
  ADC values are significantly increased in inflamed SIJs compared with controls. There is a good correlation between this diffusion-based method and STIR scores of inflammation.
  
  
  CONCLUSIONS
  We have described and provisionally validated a method for quantifying the severity of inflammation in the SIJs in ERA using ADC measurements. This method is quick, is reproducible and could potentially be automated.
authors.affiliation: 1 Academic Radiology, University College London Centre for Medical Imaging, London, UK.
authors.forename: Kanimozhi
authors.initials: K
authors.lastname: Vendhan
authors.affiliation: 1 Academic Radiology, University College London Centre for Medical Imaging, London, UK.|2 Arthritis Research UK Centre for Adolescent Rheumatology, University College London, London, UK.
authors.forename: Timothy J P
authors.initials: TJ
authors.lastname: Bray
authors.affiliation: 1 Academic Radiology, University College London Centre for Medical Imaging, London, UK.
authors.forename: David
authors.initials: D
authors.lastname: Atkinson
authors.affiliation: 1 Academic Radiology, University College London Centre for Medical Imaging, London, UK.
authors.forename: Shonit
authors.initials: S
authors.lastname: Punwani
authors.affiliation: 2 Arthritis Research UK Centre for Adolescent Rheumatology, University College London, London, UK.
authors.forename: Corinne
authors.initials: C
authors.lastname: Fisher
authors.affiliation: 2 Arthritis Research UK Centre for Adolescent Rheumatology, University College London, London, UK.
authors.forename: Debajit
authors.initials: D
authors.lastname: Sen
authors.affiliation: 2 Arthritis Research UK Centre for Adolescent Rheumatology, University College London, London, UK.
authors.forename: Yiannakis
authors.initials: Y
authors.lastname: Ioannou
authors.affiliation: 1 Academic Radiology, University College London Centre for Medical Imaging, London, UK.
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Hall-Craggs
mesh_terms: D000293:Adolescent; D000328:Adult; D001171:Arthritis, Juvenile / Q000150:complications* / Q000473:pathology*; D002648:Child; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007089:Image Enhancement; D008297:Male; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012446:Sacroiliac Joint / Q000473:pathology; D058566:Sacroiliitis / Q000150:complications* / Q000473:pathology*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D055815:Young Adult