Fibroma and fibrothecoma of the ovary: MR imaging findings

To describe the morphologic and signal intensity characteristics on magnetic resonance (MR) images of fibromas and fibrothecomas.

MR images of 11 female patients with histologically proved fibromas or fibrothecomas were reviewed, and morphologic and signal intensity characteristics of the lesions were analyzed. MR imaging findings were correlated with histologic findings.

All fibromas and fibrothecomas showed homogeneous low signal intensity on T1-weighted images. On T2-weighted images, the two smallest lesions showed homogeneous low signal intensity, and eight of the other nine lesions showed predominantly low signal intensity. Edema was noted only in larger lesions, and cystic degeneration was noted only in three of the largest lesions. On T2-weighted images, the percentage of low signal intensity in the lesion was not found to be related to lesion size, and the percentage of low signal intensity in fibromas was not significantly different from that in fibrothecomas (P = .55). Many lesions showed heterogeneous signal intensity; the solid component was distributed peripherally, and the cystic component was located centrally or eccentrically. Free intraperitoneal fluid was noted in 10 of 11 lesions and was not significantly correlated with lesion size (r = .52 and P = .10).

Because of their predominantly low signal intensity on T2-weighted images, fibromas and fibrothecomas display a relatively specific appearance on MR images.