title: Diffusion-weighted magnetic resonance imaging for detecting and assessing ileal inflammation in Crohn's disease.
abstract: BACKGROUND
  Whether diffusion-weighted imaging (DWI)-MRI is of value in detecting and assessing inflammation of ileal Crohn's disease (CD) remains poorly investigated.
  
  
  OBJECTIVE
  To compare DWI-MR enterography (MRE) with conventional MRE in estimating inflammation in small bowel CD, to determine an apparent diffusion coefficient (ADC) threshold to differentiate active from non-active lesions and to assess inter-observer agreement.
  
  
  METHODS
  Thirty-one CD patients from the Clermont-Ferrand IBD unit with ileal involvement were consecutively and prospectively included between April and June 2011. All patients underwent DWI-MRI to detect the digestive segment with the most severe lesions, which was then used to calculate the ADC. Qualitative and quantitative results were compared with conventional MRE including MaRIA (Magnetic Resonance Index of Activity) score calculation and independent activity predictors (wall thickening, oedema, ulcers). Each examination was interpreted independently by two radiologists blinded for clinical assessment.
  
  
  RESULTS
  Seventeen patients (54.8%) had active CD as defined by the MaRIA score ≥7. DWI hyperintensity was highly correlated with disease activity evaluated using conventional MRE (P = 0.001). Qualitative analysis of DW sequences determined sensitivity, specificity, positive predictive value and negative predictive value as 100%, 92.9%, 94.4% and 100% respectively. Quantitative analysis using a cut-off of 1.6 × 10(-3) mm(2)/s for ADC yielded sensitivity and specificity values of, respectively, 82.4% and 100%. Inter-observer agreement was high with regard to DWI hyperintensity (κ = 0.69, accuracy rate = 85.7%) and ADC (correlation = 0.74, P < 0.001, and concordance = 0.71, P < 0.001).
  
  
  CONCLUSIONS
  DWI-MR enterography is a well-tolerated, non-time-consuming and accurate tool for detecting and assessing inflammation in small bowel Crohn's disease.
authors.affiliation: Department of Gastroenterology, University Hospital Estaing of Clermont-Ferrand, Auvergne University, France. a_buisson@hotmail.fr
authors.forename: A
authors.initials: A
authors.lastname: Buisson
authors.forename: A
authors.initials: A
authors.lastname: Joubert
authors.forename: P-F
authors.initials: PF
authors.lastname: Montoriol
authors.forename: D
authors.initials: D
authors.lastname: Da Ines
authors.forename: D D
authors.initials: DD
authors.lastname: Ines
authors.forename: C
authors.initials: C
authors.lastname: Hordonneau
authors.forename: B
authors.initials: B
authors.lastname: Pereira
authors.forename: J-M
authors.initials: JM
authors.lastname: Garcier
authors.forename: G
authors.initials: G
authors.lastname: Bommelaer
authors.forename: V
authors.initials: V
authors.lastname: Petitcolin
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003424:Crohn Disease / Q000175:diagnosis*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D007079:Ileitis / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D055815:Young Adult