Comparison of the diagnostic accuracy of contrast‐enhanced MRI and diffusion‐weighted MRI in the differentiation between uterine leiomyosarcoma / smooth muscle tumor with uncertain malignant potential and benign leiomyoma

Purpose To compare the diagnostic accuracy of contrast‐enhanced (CE) magnetic resonance imaging (MRI) and diffusion‐weighted MRI (DWI) in the differentiation between uterine leiomyosarcoma (LMS) / smooth muscle tumor with uncertain malignant potential (STUMP) and benign leiomyoma. Materials and Methods A consecutive cohort of 8 LMS/STUMP and 25 benign leiomyomas underwent pelvic MRI exam at 3T. Two radiologists independently evaluated images based on CE‐MRI (central nonenhancement at equilibrial phase) and DWI (hyperintensity on b = 1000 s/mm 2 and hypointensity on apparent diffusion coefficients [ADC] map). The ADC values were calculated from b = 0 and 1000 s/mm 2 . Results CE‐MRI yielded a significantly superior diagnostic accuracy (0.94 vs. 0.52) and a significantly higher specificity (0.96 vs. 0.36) than DWI ( P < 0.05 for both), and remained a comparably high sensitivity as DWI (0.88 vs. 1.00). A combination of DWI and ADC value <1.08 × 10 −3 mm 2 /s (determined by receiver operating characteristic analysis) improved diagnostic accuracy, sensitivity, and specificity of DWI to 0.88, 0.88, and 0.88, respectively, by post‐hoc analysis based on the same study cohort. Conclusion For prospective differentiation between uterine LMS/STUMP and benign leiomyoma, CE‐MRI can provide accurate information and is preferable to DWI. Combination of DWI and ADC values can achieve a comparable diagnostic accuracy to CE‐MRI. J. Magn. Reson. Imaging 2016;43:333–342.