Utility of Ultrafast MRI for Suspected Acute Appendicitis with Inconclusive Ultrasound

Abstract

Introduction: Acute appendicitis is the commonest cause of Right Lower Quadrant (RLQ) pain requiring immediate surgery. The lack of confirmatory imaging diagnosis may lead to unnecessary surgery or prolonged hospital stay for monitoring. MRI appendix protocol provides a fast and accurate way to diagnose the cause of RLQ pain when the ultrasound is inconclusive. MRI can ascertain the various features of acute appendicitis and its complications as well as other differential diagnosis for RLQ pain. Aim: The purpose of this study was to evaluate the utility of ultrafast MRI appendix protocol in evaluation of RLQ pain in paediatric and reproductive age group patients with inconclusive ultrasound. Materials and Methods: This prospective study comprised of 71 patients who underwent MRI appendicitis protocol (T2 SSH TSE, T2 SPAIR, T1 TSE and DWI) within 4 hours after an inconclusive ultrasound between May 2016 and May 2017. MRI images were reviewed by independently by 2 radiologists and the diagnosis was graded as positive, negative and equivocal. The final diagnosis was established after review of operative, pathological findings and clinical follow-up for cases with no evidence of acute appendicitis on MRI. Results: Twenty one out of 71 patients had acute appendicitis. Both radiologists graded the same 22 patients as positive, and the same 34 patients as negative. The sensitivity and specificity of MRI appendix protocol in patients with inconclusive ultrasound were 100% and 97.14% respectively. The positive predictive value was 95.45% and negative predictive value was 100% and overall test accuracy was 98.21%. The Fisher’s exact test showed a p-value of <0.001 showing the correlation between MRI and clinical/pathological test for acute appendicitis is extremely statistically significant. MRI diagnosed an alternate cause of RLQ pain in about 21% of patients. Conclusion: MRI appendix protocol yields excellent results in paediatric and reproductive age patients with RLQ pain with an inconclusive ultrasound. Restriction on DWI helps in identifying acutely inflamed appendix with confidence. It helps us in ruling out acute appendicitis thus reduces negative appendectomy rate. It is a safe, reliable and potentially cost effective technique.

Keywords

• MRI abdomen
• Perforation
• Reproductive age group