Non-invasive magnetic resonance-guided focused ultrasound treatment of uterine fibroids in a large Japanese population: impact of the learning curve on patient outcome.

OBJECTIVES

To describe the learning curve effect of magnetic resonance-guided focused ultrasound surgery (MRgFUS) on the outcomes of patients treated for uterine fibroids in four centers in Japan.

METHODS

The extent of fibroid ablation (often used to measure treatment success) was evaluated using the non-perfused volume (NPV) ratio in 287 Japanese patients. The patients were divided into two equal groups according to the chronological treatment time and results were compared between these groups to estimate the learning curve effect. Results were also compared with published data from clinical trials.

RESULTS

The NPV ratio increased chronologically, from 39.3% to 54.0% (P < 0.001), indicating increasing effectiveness of the treatment with experience. The mean NPV ratios for the entire patient population were over double that of previous clinical trials (46.6% vs. 21.9%; P < 0.001). No serious complications were reported.

CONCLUSION

The learning process and accumulation of data on MRgFUS enable the optimization of treatments in order to safely achieve large NPV ratios and sustained clinical benefit.