Smooth Muscle Tumors of Uncertain Malignant Potential and Leiomyosarcomas of the Uterus: MR Findings

Purpose: To study the MR characteristics of nonbenign uterine smooth muscle tumors.

Materials And Methods: Nine patients with pathologically proven leiomyosarcomas, and three patients with smooth muscle tumors of uncertain malignant potential (SMTUMP) were included in this study. Twelve cases of benign uterine leiomyomas and variants, in which gynecologists suspected leiomyosarcomas, were also analyzed. In each case we studied the size, location, signal intensity, and contrast enhancement of the tumors.

Results: Nine of the 12 nonbenign characters had more than 50% of high-intensity areas on T2-weighted images (T2WI), and some hyperintense foci on T1-weighted images (T1WI). In the contrast study, nine of 12 nonbenign characters had well-demarcated unenhanced areas. On the other hand, only two of 12 benign characters showed such a signal intensity pattern, and none of them had a pocket-like unenhanced area.

Conclusion: Although there were some exceptions, more than 50% of high signal on T2WI, and the presence of any small high-signal areas on T1WI with unenhanced pockets were considered MR-suggestive for SMTUMPs and leiomyosarcomas.