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 (T1WI; 11/18) or T2WI (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 mm2/s) was almost equal to that of the other solid ovarian masses (1.26 ± 0.51 × 10-3 mm2/s), but lower than that for leiomyoma (1.48 ± 0.42 × 10-3 mm2/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 mm2/s) and leiomyomas (1.48 ± 0.42 × 10-3 mm2/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.