• Marjolein M N Leeuwenburgh, Bart M Wiarda, Marinus J Wiezer, Bart C Vrouenraets, Jan Willem C Gratama, Aart Spilt, Milan C Richir, Patrick M M Bossuyt, Jaap Stoker, Marja A Boermeester, and OPTIMAP Study Group.
• Department of Radiology, Surgery, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, the Netherlands. m.m.leeuwenburgh@amc.uva.nl
• Radiology. 2013 Jul 1;268(1):135-43.

PurposeTo compare the diagnostic performance of imaging strategies with magnetic resonance (MR) imaging and computed tomographic (CT) imaging in adult patients suspected of having appendicitis.Materials And MethodsInstitutional 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.ResultsBetween 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.ConclusionThe 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.

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