title: Comparison of imaging strategies with conditional contrast-enhanced CT and unenhanced MR imaging in patients suspected of having appendicitis: a multicenter diagnostic performance study.
abstract: OBJECTIVE
  To compare the diagnostic performance of imaging strategies with magnetic resonance (MR) imaging and computed tomographic (CT) imaging in adult patients suspected of having appendicitis.
  
  
  METHODS
  Institutional review board approval was obtained prior to study initiation, and patients gave written informed consent. In a multicenter diagnostic performance study, adults suspected of having appendicitis were prospectively identified in the emergency department. Consenting patients underwent ultrasonography (US) and subsequent contrast-enhanced CT if US imaging yielded negative or inconclusive results. Additionally, all patients underwent unenhanced MR imaging, with the reader blinded to other findings. An expert panel assigned final diagnosis after 3 months. Diagnostic performance of three imaging strategies was evaluated: conditional CT after US, conditional MR imaging after US, and immediate MR imaging. Sensitivity and specificity were calculated by comparing findings with final diagnosis.
  
  
  RESULTS
  Between March and September 2010, 229 US, 115 CT, and 223 MR examinations were performed in 230 patients (median age, 35 years; 40% men). Appendicitis was the final diagnosis in 118 cases. Conditional and immediate MR imaging had sensitivity and specificity comparable to that of conditional CT, which resulted in 3% (three of 118; 95% confidence interval [CI]: 1%, 7%) missed appendicitis, and 8% (10 of 125; 95% CI: 4%, 14%) false-positives. Conditional MR missed appendicitis in 2% (two of 118; 95% CI: 0%, 6%) and generated 10% (13 of 129; 95% CI: 6%, 16%) false-positives. Immediate MR missed 3% (four of 117; 95% CI: 1%, 8%) appendicitis with 6% (seven of 120; 95% CI: 3%, 12%) false-positives. Conditional strategies resulted in more false-positives in women than in men (conditional CT, 17% vs 0%; P = .03; conditional MR, 19% vs 1%; P = .04), wherease immediate MR imaging did not.
  
  
  CONCLUSIONS
  The accuracy of conditional or immediate MR imaging was similar to that of conditional CT in patients suspected of having appendicitis, which implied that strategies with MR imaging may replace conditional CT for appendicitis detection.
authors.affiliation: Department of Radiology, Surgery, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands. m.m.leeuwenburgh@amc.uva.nl
authors.forename: Marjolein M N
authors.initials: MM
authors.lastname: Leeuwenburgh
authors.forename: Bart M
authors.initials: BM
authors.lastname: Wiarda
authors.forename: Marinus J
authors.initials: MJ
authors.lastname: Wiezer
authors.forename: Bart C
authors.initials: BC
authors.lastname: Vrouenraets
authors.forename: Jan Willem C
authors.initials: JW
authors.lastname: Gratama
authors.forename: Aart
authors.initials: A
authors.lastname: Spilt
authors.forename: Milan C
authors.initials: MC
authors.lastname: Richir
authors.forename: Patrick M M
authors.initials: PM
authors.lastname: Bossuyt
authors.forename: Jaap
authors.initials: J
authors.lastname: Stoker
authors.forename: Marja A
authors.initials: MA
authors.lastname: Boermeester
mesh_terms: D000328:Adult; D001064:Appendicitis / Q000175:diagnosis* / Q000000981:diagnostic imaging; D016009:Chi-Square Distribution; D003287:Contrast Media; D003937:Diagnosis, Differential; D004636:Emergency Service, Hospital; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography
chemical_list: D003287:Contrast Media