MRI of acute appendicitis.

Appendicitis is the most common cause of acute abdominal pain resulting in surgery. While historically ultrasound (US) and computed tomography (CT) have been used to evaluate for appendicitis and its related complications, magnetic resonance imaging (MRI) has become a highly accurate and increasingly utilized modality in the last two decades, particularly in the pediatric and pregnant patient populations in whom ionizing radiation is used reluctantly. This article discusses the advantages and disadvantages of MRI as a modality to evaluate for acute appendicitis, summarizes studies of the diagnostic performance relative to CT and US, provides a standard MR protocol, and describes MRI findings typical of acute appendicitis, common complications, and other differential diagnoses. Level of Evidence: 2 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:1367-1376.