Added value of diffusion-weighted MR imaging to non-enhanced CT in the evaluation of acute abdominopelvic pain

Objective: When performing a Non-Enhanced Computed Tomography (NECT) scan, the efficacy generally reduces, and an additional CECT may become inevitable for final diagnosis. This prospective study aims to determine the added value of Diffusion Weighted Imaging (DWI) when combined to NECT in the diagnosis of acute abdominopelvic pain (acute abdomen) and the diagnostic efficacy of combined imaging (DWI and NECT) compared with CECT. Methods: Between June 2014 and August 2016, 293 patients (133 male, 160 female) imaged with NECT and DWI, and 394 control patients (174 male, 220 female) imaged with contrast-enhanced computed tomography (CECT) for acute abdominopelvic pain were enrolled in this prospective study. DWI was obtained with b factors 0, 500 and 1000 s/mm2 and assessed with qualitative analysis. Results: NECT provided 70.1% sensitivity and 76.0% specificity and 71.6% accuracy. The combined protocol (NECT and DWI) revealed 96.7% sensitivity, 82.6% specificity and 92.8% accuracy. CECT provided 93.0% sensitivity and 79.4% specificity and 90.3% accuracy. The addition of DWI to NECT provided a 26.6% and 6.6% increase in the sensitivity and, specificity respectively. There was 21.2% significant increase of accuracy in favour of the combined imaging (p<0.001). However, there was no significant difference of accuracy between CECT and combined imaging (p=0.204). Conclusion: DWI is an efficient technique for the diagnosis of acute abdominopelvic pain. We recommend using DWI when NECT is inevitable for different reasons. It may increase the diagnostic accuracy of NECT to avoid an additional CECT scan.