Uterine and Fibroid Imaging Analysis from the FIRSTT Study

Background: Women with uterine fibroids often seek uterine-preserving treatments, rather than hysterectomy. Imaging-defined endpoints following nonsurgical treatments for fibroids are limited. Materials and Methods: Fibroid Interventions: Reducing Symptoms Today and Tomorrow (FIRSTT), a randomized controlled trial of uterine artery embolization (UAE) versus magnetic resonance imaging-guided focused ultrasound surgery (MRgFUS), enrolled premenopausal women with symptomatic uterine fibroids. In this subanalysis, we report imaging results up to 36 months after UAE or MRgFUS. Magnetic resonance imaging (MRI) was performed at baseline for all women and during the 36 months after treatment if they did not meet other study endpoints. The main outcome of this subanalysis was fibroid volume reduction (defined both in terms of total fibroid load and volume of the largest fibroid), uterine volume reduction, and nonperfused volume. Results: During 2010-2014, 25 of the 37 women who were randomized and treated at Mayo Clinic had a 24-month follow-up MRI (11 UAE; 14 MRgFUS); among these women, 15 (7 UAE and 8 MRgFUS) had a 36-month follow-up MRI. Average age for the cohort was 44.1 (standard deviation, SD = 4.4) years. Nine patients had a second fibroid procedure by 36 months (seven in the MRgFUS arm and two in UAE arm). Median total fibroid load reduction was ∼50% in both treatment arms at both 24-and 36-month follow-up. Volume of the largest fibroid decreased more in the MRgFUS arm, whereas uterine volume decreased more in the UAE arm (neither reached statistical significance). At 24 months, median nonperfused volume was higher in the UAE arm (92%) than the MRgFUS arm (10%). Conclusions: Similar fibroid volume reduction was seen for the MRgFUS and UAE treatments in this comparative effectiveness study. Nonperfused volume 24 months after the procedure was higher in the UAE arm than in the MRgFUS arm.