Efficacy, Efficiency, and Safety of Magnetic Resonance-Guided High-Intensity Focused Ultrasound for Ablation of Uterine Fibroids: Comparison with Ultrasound-Guided Method.

Objective: The purpose of this study was to compare efficacy, sonication energy efficiency, treatment time and safety of magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) and those of ultrasound-guided high-intensity focused ultrasound (USgHIFU) for ablation of uterine fibroids. Materials and Methods: This study included 43 patients with 44 symptomatic uterine fibroids treated with MRgHIFU and 51 patients with 68 symptomatic uterine fibroids treated with USgHIFU. After therapy, contrast-enhanced MRI was conducted and complete ablation was defined as 100% non-perfused volume (NPV) of fibroids. Patients with completely ablated fibroids were selected for the comparison of the treatment data and sonication parameters between MRgHIFU and USgHIFU treated groups. Results: Thirteen completely ablated fibroids in 10 patients (23.3%, 10/43) were achieved with MRgHIFU and 28 completely ablated fibroids in 22 patients (43.1%, 22/51) were achieved with USgHIFU. In completely ablated fibroids, the energy-efficiency factor (EEF) was 5.1 ± 3.0 J/mm3 and 4.7 ± 2.5 J/mm3 in the MRgHIFU and USgHIFU, respectively (p = 0.165). There was a negative linear correlation between EEF and the NPV of fibroids for MRgHIFU (p = 0.016) and USgHIFU (p = 0.001). The mean treatment time was 174.5 ± 42.2 minutes and 114.4 ± 39.2 minutes in the MRgHIFU and USgHIFU procedures, respectively (p = 0.021). There were no severe adverse events and major complications after treatment. Conclusion: MRgHIFU and USgHIFU are safe and effective with the equivalent energy efficiency for complete ablation of fibroids. USgHIFU has shorter treatment time than MRgHIFU.