The Efficacy of Unenhanced MR Imaging for the Diagnosis of Acute Appendicitis: A Performance Comparison Versus Abdominal Ultrasonography

ABSTRACT

PURPOSE: To evaluate the efficacy of unenhanced MR imaging compared to the diagnostic accuracy, advantage, and limitations of abdominal ultrasonography in the diagnosis of acute appendicitis. MATERIALS AND METHODS: The study included 40 patients suspected of having acute appendicitis and who were subjected to an unenhanced MR image, as well as an abdominal ultrasonography. A T1 FLASH in an axial image, a chemical shift-selective fat suppressed T2 HASTE in an axial image, as well as a T2 HASTE in an axial and coronal image were obtained as unenhanced MR images. The diagnosis was established based on a surgical or clinical follow-up of the unenhanced MR results, which were then statistically compared to the ultrasonographic results. RESULTS: The surgical or clinical follow-up results revealed that 25 patients were positively diagnosed with appendicitis. Of these, 7 patients had symptoms of acute appendicitis with no pathologic diagnoses, whereas the 8 remaining patients were diagnosed with another condition. The sensitivity and accuracy of the unenhanced MR imaging was 92% and 90%, compared to ultrasonography which was 68% and 72.5% accurate, respectively. The differences in sensitivity and accuracy between the two methods were found to be statistically significant (p < .05, chi-square test). Based on these results, unenhanced MR imaging was superior to sonography for the diagnosis of appendicitis. CONCLUSION: Unenhanced MR imaging may be a useful modality for the diagnosis of acute appendicitis, especially for suboptimal or nondiagnostic sonographies, as well as patients that are particularly sensitive to radiation exposure.