Diagnostic performance of magnetic resonance imaging in the detection of appendicitis in adults: a meta-analysis

Rationale and objectives: Perform a meta-analysis evaluating the diagnostic performance of magnetic resonance imaging (MRI) for the diagnosis of acute appendicitis.

Materials and methods: MEDLINE and EMBASE were queried between January 1995 and December 2009. Prospective and retrospective studies were included if they: used MRI as a diagnostic test for appendicitis, used pathology or clinical follow-up as the reference standard, and reported absolute number of true-positive, true-negative, false-positive, and false-negative results, or stated sufficient data to derive these values. Summary sensitivity, summary specificity, positive and negative likelihood ratios (LR+) and (LR-), and diagnostic odds ratio were calculated. Heterogeneity of the results was assessed using Forest plots and the value of inconsistency index (I(2)).

Results: The inclusion criteria were fulfilled by eight articles with a total of 363 patients (mean age 26.9 ± 7.2 years; 86.2 % female). The appendix was not found in eight patients, with one article not reporting such data. The summary sensitivity was 97% (92%-99% at 95% confidence interval [CI]) and summary specificity was 95% (CI: 94%-99%), with a LR+ of 16.3 (CI: 9.1-29.1) and a LR- of 0.09 (CI: 0.04-0.197). Diagnostic odds ratio was 299.85 (CI: 97.5-921.61). No heterogeneity was found in the sensitivity (I(2) = 0.0, P = .4589). Minimal heterogeneity was found in the specificity (I(2) = 21.9%, P = .2553).

Conclusion: MRI appears promising in the evaluation of acute appendicitis, although larger future studies are warranted to confirm the results.