Clinical Question

Can MRI safely and effectively replace CT in the evaluation of suspected appendicitis in pediatric patients?

Impact

Appendicitis is prevalent in pediatric populations and the leading cause of emergent abdominal surgery (1). CT imaging is standard-of-care for children presenting with symptoms of appendicitis and is used to triage patients to emergency surgery.

Approach

The standard protocol for evaluation of acute appendicitis in most hospitals is an abdominal CT scan with oral contrast. At our institution, we performed an ultrasound to assess for appendicitis before triaging to CT for equivocal cases in order to spare some children the need for the radiation exposure. As of early 2015 we have been able to replace this CT scan with a limited abdomen/pelvis study using MRI. The limited MRI of abdomen/pelvis is rapid (approximately 20 minutes), cost-effective (costing half the price of regular abdominal MRI scan with contrast and equal to the CT study with contrast for appendicitis), and confers less potential risk to the patient by eliminating radiation exposure.

Gains and Losses

Replacing CT with MRI for the evaluation of suspected appendicitis in children eliminates potential risk of radiation related to CT and is cost neutral in our institution. Care must be taken to have measures in place to reduce motion in children undergoing MRI for appendicitis. Using state-of-the-art rapid MRI imaging techniques, we have been successful in imaging suspected appendicitis in children as young as five years old. Children younger than this age may not be able to undergo MRI as these studies cannot be performed with sedation and some younger children may not be able to cooperate for the twenty minute length of the exam.

Preliminary Data

The diagnostic quality of MRI is equivalent or superior to CT imaging for appendicitis in children as long as motion dose not degrade the image. The MRI without contrast study is cost neutral compared to the CT with contrast study in our institution and spares children exposure to radiation for a very common indication. Included in this data set are ten pairs of MRI and CT images of children who were ordered imaging of the abdomen/pelvis to rule out acute appendicitis. For illustrative purposes we have selected five cases of acute appendicitis and five cases negative for appendicitis in a range of ages from 5-16 years old. MRI images where acquired on a 3.0T magnet (Skyra, Siemens Healthcare, Erlangen, Germany) and 64 slice CT scanners (Somatom Definition Flash, Siemens Healthcare, Erlangen Germany or HD750, GE Healthcare, Little Chalfont, UK). The MRI appendicitis protocol includes coronal, sagittal, and axial HASTE sequences and an axial HASTE sequence with fat saturation. All image are acquired with breathhold or navigator from mid kidney through the bladder with a 3mm slice thickness and no gap. Optional add-on sequences include an axial TRUEFISP, an axial T2 TSE, and an axial DWI (b=50, 800) acquired at the region of interest.

Acknowledgements

No acknowledgement found.

References

(1) Addiss DG, Shaffer N, Fowler BS, Tauxe RV. The epidemiology of appendicitis and appendectomy in the United States. Am J Epidemiol. 1990 Nov;132(5):910-25.