Leiomyoma Shrinkage After MRI-Guided Focused Ultrasound Treatment: Report of 80 Patients

Abstract

OBJECTIVE. The purpose of this study was to assess the degree of leiomyoma ablation and shrinkage after MRI-guided focused ultrasound treatment performed according to U.S. Food and Drug Administration protocols for commercial trials. MATERIALS AND METHODS. A total of 147 symptomatic leiomyomas in 80 women (average age, 46 years; range, 34–55 years) were managed with MRI-guided focused ultrasound. The average volume of treated fibroids was 175 ± 201 (SD) cm³. Before treatment, T2-weighted MR images in three planes were obtained to measure leiomyoma volume. Immediately after treatment, T1-weighted contrast-enhanced fat-suppressed MR images in three planes were used to measure nonperfused volume ratio. Similar images obtained 6 months after treatment were used to determine leiomyoma shrinkage. Qualitative and quantitative relations between fibroid volume, nonperfused volume ratio at treatment, and 6-month shrinkage were measured. RESULTS. The average nonperfused volume ratio was 55% ± 25% immediately after treatment. Six months after treatment, the average volume of treated fibroids had decreased to 112 ± 141 cm³ (n = 81) (p < 0.0001) with an average volume reduction of 31% ± 28%. A linear regression model showed highly significant correlation between posttreatment nonperfused volume ratio and shrinkage at 6 months (p < 0.0001). CONCLUSION. MRI-guided focused ultrasound therapy for leiomyoma can result in nonperfused volume ratio and shrinkage that exceed those in previous clinical trials because the treatment guidelines have been relaxed to allow a greater amount of tissue ablation. The results suggest that a larger nonperfused volume ratio can be achieved, resulting in greater shrinkage and improved relief of symptoms.