title: Role of magnetic resonance imaging in evaluation of the activity of perianal Crohn's disease.
abstract: OBJECTIVE
  To evaluate the diagnostic ability of contrast-enhanced Magnetic Resonance Imaging (MRI) in assessment of the activity of perianal fistulas in Crohn's disease (CD) patients, compared to clinical data.
  
  
  METHODS
  Fifty CD patients (25 men; mean[SD] age: 40.4[12.6] years) with known or suspected perianal fistulas underwent perianal space MRI. Radiological activity of disease was measured as the percentage increase (PI) of ROI values of fistulas in relation to ROI values of healthy local fat, after contrast administration. Clinical activity of disease was defined according to Perianal Disease Activity Index (PDAI) and Fistula Drainage Assessment (FDA).
  
  
  RESULTS
  Forty-two patients presented perianal disease at MRI (55 fistulas identified). An association between both fistula's PI and PDAI (Pearson's coefficient 0.512, p<0.0001) and between PI and FDA (p=0.003) was demonstrated. Areas under ROC curves of PI values in relation to PDAI and FDA were respectively 0.876 [95%CI=(0.743-1.00), p<0.001] and 0.784 [95%CI=(0.588-0.980), p=0.003]. A cut-off value of PI, calculated on these preliminary data, correctly classified more than 90% of fistulas.
  
  
  CONCLUSIONS
  Contrast-enhanced MRI with PI calculation offered practical information about activity of perianal fistulas and might be helpful in providing a comprehensive evaluation of CD perianal disease.
authors.affiliation: Department of Diagnostic and Interventional Radiology, San Paolo Hospital, Università degli Studi di Milano, via A. di Rudinì 8, 20142 Milan, Italy. chiara.villa@hotmail.it
authors.forename: Chiara
authors.initials: C
authors.lastname: Villa
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pompili
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Franceschelli
authors.forename: Alice
authors.initials: A
authors.lastname: Munari
authors.forename: Giovanni
authors.initials: G
authors.lastname: Radaelli
authors.forename: Giovanni
authors.initials: G
authors.lastname: Maconi
authors.forename: Gian Paolo
authors.initials: GP
authors.lastname: Cornalba
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001004:Anus Diseases / Q000150:complications* / Q000175:diagnosis*; D003424:Crohn Disease / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D005402:Fistula / Q000150:complications* / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult