PurposeTo compare potential discriminatory magnetic resonance imaging (MRI) features of primary fallopian tube carcinoma (PFTC) and primary epithelial ovarian cancer (EOC). Materials and MethodsMRI features (the laterality, shape, size, signal intensity, enhancement of solid portion, amount of ascites, peritoneal planting, lymph nodes, or distant metastasis) of 27 tumors in 23 patients with PFTC confirmed by surgery and pathology were compared with 42 tumors in 37 patients with EOC. ResultsThe mean maximum diameter was 6.10.7 cm in PFTC versus 10.2 +/- 0.6 cm in EOC. MRI features of PFTC were sausage-like shape (19/27, 70%), or irregular (8/27, 30%) shape; solid (20/27, 74%) or cystic-solid (7/27, 26%) mass; homogeneous (21/27, 78%) or heterogeneous (6/27, 22%) signal on T-2-weighted images; mild (8/27, 30%), moderate (13/27, 48%), or prominent (6/27, 22%) enhancement; associated hydrosalpinx (13/27, 48%) or intrauterine fluid accumulation (7/23, 30%). Significant differences between PFTC and EOC were found in the size, shape, configuration, signal homogeneity, and enhancement pattern, associated hydrosalpinx, and intrauterine fluid accumulation (P<0.001,<0.001, 0.015, 0.001,<0.001,<0.001, and 0.001, respectively). ConclusionPFTC often appears as a small-sized solid mass, with a sausage-like shape, homogeneous signal, mild or moderate enhancement, hydrosalpinx, or intrauterine fluid accumulation. Our preliminary study shows that MRI can identify the characteristic features of PFTC and differentiate PFTC from EOC. J. Magn. Reson. Imaging 2015;42:42-47. (c) 2014 Wiley Periodicals, Inc.