Diffusion‐weighted MRI: Role in detecting abdominopelvic internal fistulas and sinus tracts

Purpose: To retrospectively determine the incremental value of diffusion‐weighted MR‐imaging (DW‐MRI) to T2‐weighted (T2w) images in diagnosis of internal fistulas (IFs) and sinus tracts (STs). Materials and Methods: Fourteen patients with 25 IFs and STs arising from the small bowel (20), colon (4) and biliary tract (1) were included. Two independent observers reviewed T2w images, T2w+DW‐MRI images and T2w+contrast enhanced T1‐weighted (CE T1w) images at three sessions to detect IF/ST based on a confidence scale of five. Sensitivity and confidence score of each session was compared. Results: 10/25 (40%) and 9/25 (36%) IFs and STs were detected on T2w images by observer 1 and 2, respectively. Both observers detected 19/25 (76%) and 24/25(96%) IFs and STs on T2w+DW‐MRI and T2w+CE T1w images, respectively. Detection rate and confidence score improved significantly by combining T2w images with DW‐MRI or CE T1w images (reader 1 + 2: P ≤ 0.01). There was no significant difference between the IF/ST detection rate of T2w+DW‐MRI and T2w+CE T1 image combinations. Confidence scores with T2w+CE T1w images were significantly greater than DW‐MRI+T2w images (reader 1: P = 0.01; reader 2: P = 0.03). Conclusion: DW‐MRI showed additional value to T2w imaging for diagnosis of IF and ST. DW‐MRI can be a useful adjunct, especially for patients with renal failure. J. Magn. Reson. Imaging 2012;35:125‐131. © 2011 Wiley Periodicals, Inc.