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 T(1)-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 [Formula: see text] 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 T(1)-weighted imaging) were retrospectively evaluated. MRI was qualitatively evaluated for the presence of high-intensity rim around a mass on fat-saturated T(1)-weighted images, and low-intensity rim on T(2)-weighted images and on SWS (susceptibility-weighted imaging [SWI] or T(2)-star-weighted angiography [SWAN]). RESULTS: The high-intensity rim on T(1)-weighted images, low-intensity rim on T(2)-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 T(1)-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.