Differentiation between Ovarian Fibroma and Subserosal Leiomyoma by MR Imaging

Choi, Sang Yeol; Lee, Jun Woo; Kim, Chang Won; Kim, Yong Woo; Lee, Suck Hong

Abstract

PURPOSE: To evaluate the findings and differential points of ovarian fibroma and subserosal leiomyoma, as seen on MR images.
MATERIALS AND METHODS
The MR imaging findings of 31 surgically confirmed cases of ovarian fibroma(n=6) and subserosal leiomyoma (n=25 ; 28 lesions) were evaluated. Multiplanar T1- and T2-weighted and postcon-trast T1-weighted images were obtained using a 1.5T MR unit, and histologic examination was also performed. The MR findings were analyzed in terms of signal intensity, the presence and definition of margin, the histo-logic finding of hyperintense lesion on T2-weighted images, the presence of the bridging vessel sign, degree of enhancement, and the presence of ipsilateral ovary and ascites.
RESULTS
Both fibromas and leiomyomas showed hypo-or isointensity compared with uterine myometrium on T1-weighted images and compared with skeletal muscle on T2-weighted images. The latter revealed intratu-moral hyperintense lesions in most cases of ovarian fibroma and subserosal leiomyoma. Three of four ovarian fibromas had a well defined margin after cystic change, but in 24 of 26 subserosal leiomyomas the margin was ill defined. The "bridging vessel sign" was visible only in subserosal leiomyomas (22/28), and in all cases the enhancement of ovarian fibromas were less than that of myomtetrium. Subserosal leiomyomas (12/28), seen on enhancement as isointense or hyperintense to myometrium, showed a greater degree of enhancement than ovarian fibromas (0/6). Ipsilateral ovary was rarely seen in ovarian fibromas (1/6), but commonly seen in sub-serosal leiomyomas (20/25). Ascites was present in one case of ovarian fibroma.
CONCLUSION
A defined margin of an intratumoral hyperintense lesion, as seen on T2-weighted images, and the presence or absence of the "bridging vessel sign" and ipsilateral ovary are useful signs when differentiating be-tween ovarian fibromas and subserosal leiomyomas.