Pitfalls in Abdominal Diffusion-Weighted Imaging: How Predictive is Restricted Water Diffusion for Malignancy

OBJECTIVE. As diffusion-weighted imaging is increasingly implemented into routine protocols of abdominal MRI, abnormal findings in expected and unexpected locations become more common. The aim of our retrospective study was to investigate the specificity of restricted diffusion in differentiation of benign from malignant abdominal disease.MATERIALS AND METHODS. Two hundred thirty consecutively registered patients underwent abdominal MRI including diffusion-weighted imaging (single-shot spin-echo echo-planar sequence) with b values of 0, 150, 500, and 1,000 s/mm2. Lesions were detected by two blinded readers using only the images with a b value of 1,000 s/mm2, and representative apparent diffusion coefficients were measured. Lymph nodes were not documented.RESULTS. Fifty-two of the 230 patients had a total of 55 lesions with restricted diffusion (23.9%). The mean apparent diffusion coefficient was 809 mm2/s. Forty-three lesions (78.2%) were malignant. The 12 benign lesions were liver hemangioma, liver aden...