To MRI or Not to MRI: That is the Question with Pediatric Appendicitis

MRI should be the best first-line modality for identifying children who have appendicitis, according to some experts. But, others disagree, citing a number of reasons why it should still come in second to ultrasound or CT.

In point-counterpoint articles published recently in the American Journal of Roentgenology, pediatric radiology specialists addressed both the benefits and potential drawbacks to using unenhanced MRI with children who present with abdominal pain.

“The evaluation of acute abdominal pain remains a challenge because of non-specific clinical presentation, particularly in young children…focused abdominal ultrasound as the first-line imaging technique, however, has failed to deliver consistent results across various healthcare facilities,” said Unni K. Udayasankar, M.D., vice chair of quality and safety at the University of Arizona Health Sciences. “When cross-sectional imaging techniques are considered, certain factors make MRI an attractive initial option for use in pediatric patients with suspected appendicitis.”

Related Content: Abdominal CT Raises Blood Cancer Risk in Appendicitis Patients, Particularly Kids

In his argument, Udayasankar laid out several points that support using unenhanced MRI first to determine whether a child might have appendicitis.

Less exposure: MRI does not use ionizing radiation, and unenhanced scans do not require the administration of IV contrast material that can prompt allergic reactions in some children. Due to lower visceral fat content in these patients and the low-contrast resolution of low-dose CT, MRI also does a better job of visualizing the appendix and any right lower quadrant inflammatory changes in children.

Technology improvements: Recent advancements in MRI technology and sequence development allow for greater soft-tissue contrast, decreased motion sensitivity, and shorter time scans, he said. Even technologists with less experience can capture high-quality diagnostic images in less than 10 minutes, using robust, tailored MRI protocols of four or five sequences. These shorter protocols also reduce the need for sedation.

More comfortable: Graded compression, which is painful and necessary to capture actionable images with ultrasound, is not needed with MRI. MRI images also provide better views of the retrocecal appendix or pelvic appendix.

More information: Alongside providing high-quality images for diagnosing appendicitis, a tailored MRI approach for abdominal pain can also shed light on what else might be behind the discomfort by visualizing the kidneys, pancreas, liver, and other gastrointestinal structures.

Related Content: Ultrasound Surpasses CT in Imaging Kids for Appendicitis

Based on these benefits, Udayasankar said, MRI should be the first-line modality option with these patients.

“Unenhanced MRI should be performed early and more often in the [emergency department] in children with abdominal pain because it provides a dependable comprehensive imaging evaluation of acute abdominal and pelvic conditions and reduces delay in clinical care,” he said.

However, according to experts from Penn State Children’s Hospital, there are several factors that must be considered before opting for unsedated MRI with children suspected of appendicitis.

“Our experience with MRI assessment for possible pediatric appendicitis allows us to delineate the limitations that radiologists should consider if choosing MRI as their first-line modality rather than electing to continue with either ultrasound or CT,” said James M. Brian, M.D., Penn State Health radiologist, and Michael M. Moore, M.D., associate professor of radiology and pediatrics at Penn State Hershey Medical Center.

Before making any decisions about using MRI as a front-line modality, they said, providers must consider four factors: access, individual patient characteristics, cost, and interpretation.

Access: Community and rural hospitals typically do not have the same level of resources enjoyed by academic medical institutions, they said. Plus, in many cases MRI access can be tied up with scans on non-emergent sedated patients or the low volume of emergency cases does not support overnight operations. If a facility has sufficient ultrasound access and experienced pediatric sonographers, it could be best to slate MRI as the back-up option when the ultrasound does not offer clarity.

Individual patients: Staying still long enough for a 15 minute-to-21 minute unsedated MRI scan can frequently be too difficult for young patients or those who are developmentally delayed. This situation is rare – research shows only 3 percent of patients end up requiring sedation – but, those individual patient factors have to be considered before deciding to proceed with a first-line MRI, they said.

Cost: Unenhanced MRI costs more than an ultrasound or IV-enhanced CT scan does. Because imaging is most often needed with children who are at intermediate-to-high risk pre-test probability, ultrasound is the most cost-effective imaging, they advised, followed by CT if the appendix is not visualized or secondary signs exist. Enough evidence is not available to justify the cost effectiveness of first-line MRI for appendicitis.

Interpretation: Pediatric radiologists or interpreting providers who have strong abdominal MRI experience are typically needed to effectively interpret MRI scans for appendicitis in children. In most cases, a radiologist is more comfortable and familiar with ultrasound or CT, they said, noting that the use of low-dose CT screening can mitigate concerns about ionizing radiation.

Given these obstacles, despite MRI’s capabilities with appendicitis evaluation, radiologists must proceed thoughtfully before proceeding with this modality, they said.

“As radiologists in 2021, we are fortunate to have a plethora of evidence-based pediatric appendicitis imaging modalities from which to choose,” they said. “The modality that provides accurate diagnostic information for a particular patient is the correct choice.”

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