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.

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