Evaluation of Red Degeneration of Uterine Leiomyoma with Susceptibility-weighted MR Imaging.

PURPOSE: Red degeneration of uterine leiomyoma (RDL) is a hemorrhagic infarction caused by peripheral venous thrombosis. The peripheral high-intensity rim on T1 -weighted MRI is characteristic for RDL; however, it may not be observed at all the phases of RDL. Susceptibility-weighted MR sequences (SWS) have exquisite sensitivity to blood products, and we hypothesized that the low-intensity rim due to the T2 * shortening effects of blood products may be more clearly demonstrated on SWS. The purpose of this study is to evaluate the capability of SWS for the diagnosis of RDL.

METHODS: Surgically proven 15 RDL, which showed suggestive MRI findings (high-intensity rim or entirely high signal intensity on T1 -weighted imaging) were retrospectively evaluated. MRI was qualitatively evaluated for the presence of high-intensity rim around a mass on fat-saturated T1 -weighted images, and low-intensity rim on T2 -weighted images and on SWS (susceptibility-weighted imaging [SWI] or T2 -star-weighted angiography [SWAN]).

RESULTS: The high-intensity rim on T1 -weighted images, low-intensity rim on T2 -weighted images and on SWS were observed in 47%, 47%, and 100% of RDL, respectively. The other 53% of lesions showed entirely high signal intensity on T1 -weighted images. Pathological examination revealed coagulative necrosis in all 15 lesions.

CONCLUSION: SWS may be helpful for the diagnosis of RDL by revealing characteristic peripheral low-intensity rim.