### Dynamic contrast-enhanced MRI for the prediction of volumetric response of uterine leiomyomas following uterine artery embolization

This study aimed to evaluate the utility of using contrast enhancement (CE) effects of uterine leiomyoma in dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) as a predictor of uterine leiomyoma volume reduction (VR) following uterine artery embolization (UAE). We retrospectively studied 22 women who underwent pre-UAE pelvic MRI with DCE-MRI and post-UAE pelvic MRI without DCE-MRI. The MRI sequences included conventional and fat-suppressed DCE-MRI. Percent volume response was determined using axial and sagittal T2-weighted imaging. The ratio between the signal intensity (SI) of the leiomyoma and that of the psoas major or iliopsoas muscle (SI ratio) was used to measure CE. In addition, the ratio of change in CE ratio during DCE-MRI was used to assess the CE pattern. We divided the target leiomyomas into two groups according to the volume reduction (VR) rate. Next, we examined whether there was a significant correlation between VR rate and SI ratio in each phase on DCE-MRI, we also assessed the ratio of change in CE ratio during DCE-MRI, age, and pre-UAE leiomyoma volume using the Mann–Whitney U test. We grouped leiomyomas in 10% increments from 50% to 90%, VR rates and decided to perform a total of five statistical tests. A total of 57 leiomyomas with preprocedural volumes ranging from 6.27 to 949.15 cm3 (135.20 ± 197.33 cm3) were included. The time between UAE and follow-up MRI was 3 - 14 months (mean, 9.09 months). The leiomyoma VR rate following UAE ranged from -85.51% to 99.94% (55.3 ± 33.85%). We found that between leiomyomas with VR rate of ≥ 90% and those with VR rate of < 90%, there was a significant difference in SI ratio at 35 sec after contrast material injection (CMI) (p = 0.0499), the ratio of change in CE ratio from 35 to 60 sec after CMI (p = 0.0153), and the ratio of change in CE ratio from 35 to 80 sec after CMI (p = 0.0185). Thus, DCE-MRI can be considered an effective and predictive tool for the therapeutic effect of UAE.