Could unenhanced MR replace CT when diagnosing pediatric appendicitis?

Ultrasonography followed by CT is often viewed as the industry standard for diagnosing pediatric appendicitis, but could unenhanced MR imaging, used in place of CT, produce similar results?

A team of researchers from the Warren Alpert Medical School of Brown University/Rhode Island Hospital in Providence, Rhode Island, sought to find out, performing a retrospective study of more than 1,900 patients who underwent diagnostic imaging for suspected appendicitis in 2011 and 2012. The authors reviewed the electronic medical records and imaging reports for all patients. Imaging reports were re-viewed and classified as positive, negative or equivocal for appendicitis and correlated with surgical and pathology reports.

“In January 2011, the members of our practice made a commitment to replace CT with unenhanced MR imaging for pediatric patients suspected of having appendicitis who have equivocal US findings,” wrote lead author Elizabeth H. Dibble, MD, and colleagues. “The purpose of our study was to determine, in a large cohort, the diagnostic performance of a staged algorithm that includes initial US followed by conditional unenhanced MR imaging for the imaging work-up of patients with pediatric appendicitis,”

According to their research, recently published in Radiology, ultrasonography followed by unenhanced MR imaging is effective for the diagnosis of pediatric appendicitis. The staged algorithm had an overall sensitivity of more than 98 percent and specificity of more than 97 percent.

“The results of our study demonstrate that a staged algorithm of ultrasonography followed by unenhanced MR imaging can be highly sensitive and specific for pediatric appendicitis,” Dibble et al. wrote. “When MR imaging is available, the role of CT in the assessment of suspected pediatric appendicitis should be minimized.”

Additional results from the study included:

• Seven of the 1,982 patients presented false-negative results with the combination of ultrasonography and MR imaging.
• The negative predictive value of the staged algorithm was 99.5 percent, or 1,530 of 1,537 patients.

The authors added their study did have several limitations, including its retrospective design. They noted their protocol varied during the study period due to intermittent review by the division director in an attempt to optimize visualization of the appendix while decreasing the total examination time.