Utility of diffusion-weighted imaging in the diagnosis of acute appendicitis

To evaluate the value of diffusion-weighted MRI (DWI) in the diagnosis of acute appendicitis. 119 patients with acute appendicitis and 50 controls were enrolled in this prospective study. DWI was obtained with b factors 0, 500 and 1000 s/mmA(2) and were assessed with a visual scoring system by two radiologists followed by quantitative evaluation of the DW images and ADC maps. Histopathology revealed appendicitis in 79/92 patients (78%) who had undergone surgery. On visual evaluation, except for one patient with histopathologically proven appendicitis all inflamed appendixes were hyperintense on DWI (98.7%). Quantitative evaluation with DW signal intensities and ADC values revealed a significant difference with normal and inflamed appendixes (p < 0.001). The best discriminative parameter was signal intensity (b 500). With a cut-off value of 56 for the signal intensity the ratio had a sensitivity of 99% and a specificity of 97%. The cut-off ADC value at 1.66 mmA(2)/s had a sensitivity of 97% and a specificity of 99%. DWI is a valuable technique for the diagnosis of acute appendicitis with both qualitative and quantitative evaluation. DWI increases the conspicuity of the inflamed appendix. We recommend using DWI to diagnose acute appendicitis.