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.

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.

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.

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.