Non-Visualization of the Appendix Without Inflammatory Features on MRI Excludes Acute Appendicitis in Children and...

Area of Science:

• Radiology
• Pediatric Imaging
• Gastrointestinal Imaging

Background:

• Appendicitis is a common surgical emergency in children and young adults.
• Magnetic Resonance Imaging (MRI) is increasingly used for appendicitis diagnosis.
• Non-visualization of the appendix on MRI can present a diagnostic challenge.

Purpose of the Study:

• To evaluate if the absence of inflammatory findings on MRI, with a non-visualized appendix, can exclude appendicitis in pediatric and young adult patients.
• To determine the diagnostic performance, specifically the Negative Predictive Value (NPV), of this imaging scenario.

Main Methods:

• Retrospective review of 1025 MRI examinations for appendicitis.
• Analysis of appendix visualization, presence of inflammatory features, and follow-up diagnoses (imaging and surgical).
• Calculation of NPV for cases with a non-visualized appendix and no inflammatory findings.

Main Results:

• The appendix was not visualized in 25.5% of cases (265/1025).
• Of these, 97.0% (257/265) showed no inflammatory features.
• In the 257 cases with a non-visualized appendix and no inflammation, none were diagnosed with appendicitis, yielding a 100% NPV.

Conclusions:

• MRI demonstrating a non-visualized appendix without adjacent inflammation is highly reliable in excluding acute appendicitis.
• This imaging finding supports safe clinical management without further investigation in select pediatric and young adult populations.
• Appropriate clinical correlation and follow-up remain essential.