Added Value of Diffusion-Weighted MR Imaging to Non-Enhanced CT in the Evaluation of Acute Appendicitis

Background: Although non-enhanced CT (NECT) can be applied for the diagnosis of acute appendicitis in obligatory conditions such as impaired renal function, it is not as effective as contrast-enhanced CT. Objectives: This prospective study aims to determine the added value of diffusion weighted imaging (DWI) in the diagnosis of acute appendicitis when combined with non-enhanced computed tomography (NECT). Patients and Methods: Between June 2014 and January 2017, 94 patients (48 male, 46 female) imaged with NECT and DWI for acute appendicitis were enrolled in this prospective study. DWI was obtained with b factors 0, 500 and 1000 s/mm2, and assessed with visual and quantitative analysis. Results of NECT and DWI, and combined imaging (NECT and DWI) were analyzed by means of sensitivity, specificity and accuracy. Results: NECT and DWI provided 91.5% - 94.3% sensitivity, 82.6% - 86.9% specificity and 89.3% - 92.5% accuracy, respectively. The combined protocol (NECT and DWI) revealed 98.5% sensitivity, 95.8% specificity and 97.8% accuracy. The addition of DWI to NECT provided a 7%, 13.2% and 8.5% increase in the sensitivity, specificity and accuracy, respectively. This increase was statistically significant (P < 0.05). Conclusion: DWI is an efficient technique for the diagnosis of acute appendicitis. This even may become more efficient if added to a NECT scan. We recommend using DWI when NECT is inevitable for different reasons. It may increase the diagnostic accuracy of NECT to avoid an additional contrast-enhanced CT scan.