Appendicitis: Role of MRI.

The diagnosis of pediatric appendicitis can be difficult, with a substantial proportion misdiagnosed based on clinical features and laboratory tests alone. Accordingly, advanced imaging with ultrasound (US), computed tomography (CT), and/or magnetic resonance imaging has become routine for most children undergoing diagnostic evaluation for appendicitis. There is increasing interest in the use of US as the primary imaging modality and reserving CT as a secondary diagnostic modality in equivocal cases. Magnetic resonance imaging, using a rapid protocol, without contrast or sedation, has been found to be highly sensitive and specific in the evaluation of children with acute right lower quadrant pain in a number of studies. Because magnetic resonance imaging has the advantage over CT of not using contrast or ionizing radiation, it may replace CT in many instances, whether after US as part of a stepwise imaging algorithm or as a primary imaging modality. Accessibility and cost, however, limit its more widespread use currently.