Diagnostic accuracy and patient acceptance of MRI in children with suspected appendicitis.

OBJECTIVE: To compare magnetic resonance imaging (MRI) and ultrasound in children with suspected appendicitis.

METHODS: In a single-centre diagnostic accuracy study, children with suspected appendicitis were prospectively identified at the emergency department. All underwent abdominal ultrasound and MRI within 2 h, with the reader blinded to other imaging findings. An expert panel established the final diagnosis after 3 months. We evaluated the diagnostic accuracy of three imaging strategies: ultrasound only, conditional MRI after negative or inconclusive ultrasound, and MRI only. Significance between sensitivity and specificity was calculated using McNemar's test statistic.

RESULTS: Between April and December 2009 we included 104 consecutive children (47 male, mean age 12). According to the expert panel, 58 patients had appendicitis. The sensitivity of MRI only and conditional MRI was 100% (95% confidence interval 92-100), that of ultrasound was significantly lower (76%; 63-85, P < 0.001). Specificity was comparable among the three investigated strategies; ultrasound only 89% (77-95), conditional MRI 80% (67-89), MRI only 89% (77-95) (P values 0.13, 0.13 and 1.00).

CONCLUSION: In children with suspected appendicitis, strategies with MRI (MRI only, conditional MRI) had a higher sensitivity for appendicitis compared with a strategy with ultrasound only, while specificity was comparable.

KEY POINTS: • In children, MRI has a higher sensitivity for appendicitis than ultrasound. • Ultrasound followed by MRI in negative or inconclusive findings is accurate. • The tolerance for ultrasound and MRI in children is comparable. • MRI can be performed in children in an emergency setting.