Value of 3.0 T diffusion-weighted imaging in discriminating thecoma and fibrothecoma from other adnexal solid masses

BACKGROUND: To investigate the value of diffusion-weighted imaging (DWI) at 3.0 T (3T), and especially the apparent diffusion coefficient (ADC), in discriminating ovarian thecoma from other adnexal solid masses. METHODS: Eighteen thecomas or fibrothecomas, 14 ligamentous leiomyomas, and 24 other ovarian solid tumors underwent prospective DWI magnetic resonance imaging (MRI) in addition to routine MRI on a 3T MRI machine. The baseline characteristics, components, and conventional MRI and DWI-MRI signals for the thecomas were recorded. The ADC values (ADCs) were measured for each group and compared. RESULTS: The thecomas often appeared as homogeneous isointensity (17/18) on T1-weighted images (T(1)WI; 11/18) or T(2)WI (11/18) on DWI-MRI, with minor (9/18) or mild (6/18) enhancement. The mean ADC value for thecoma (1.20 ± 0.45 × 10(−3) mm(2)/s) was almost equal to that of the other solid ovarian masses (1.26 ± 0.51 × 10(−3) mm(2)/s), but lower than that for leiomyoma (1.48 ± 0.42 × 10(−3) mm(2)/s), although not significantly so. There was a significant difference (p = 0.043) in the ADCs of the benign ovarian solid masses (1.16 ± 0.47 × 10(−3) mm(2)/s) and leiomyomas (1.48 ± 0.42 × 10(−3) mm(2)/s). CONCLUSIONS: There is no significant difference in ADC between thecoma and other adnexal solid masses, but the ADCs of thecomas are lower than those of leiomyomas.