Volumetric MR-guided high-intensity focused ultrasound ablation of uterine fibroids: treatment speed and factors influencing speed

Abstract

To assess the treatment speed of volumetric magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) ablation of symptomatic uterine fibroids, with a focus on factors affecting treatment speed. We received Institutional Review Board approval, and informed consent was obtained from all participants. Among 109 patients referred, 43 women (39.4 %) (mean age, 43.7 years), with 112 fibroids passed the screening. We treated 53 symptomatic uterine fibroids (47.3 %, 53/112) (volume, 341.2 ± 256.5 ml) using volumetric MR-HIFU ablation. We assessed procedure times, non-perfused volume (NPV) and treatment speed (NPV/treatment time). We statistically analysed the factors affecting treatment speed using multiple logistic regression tests. Technical success was achieved in 42 of 43 cases. MR room time (from entrance to exit) and treatment time (from first to last sonication) were 216.0 ± 40.6 min and 131.5 ± 55.9 min, respectively. Immediate NPV was 178.9 ± 147.3 ml, which was 57.4 ± 25.5 % of the fibroid volume. Treatment speed was 81.8 ± 48.0 ml/h. Multivariate analysis showed that a large fibroid volume (P < 0.001), a low signal intensity ratio of fibroid to skeletal muscle on T2-weighted images (P = 0.009) and timing after completion of the learning curve (P < 0.001) significantly increased treatment speed. Volumetric MR-HIFU ablation can effectively treat symptomatic uterine fibroids. The treatment speed appeared to improve when treating large and/or dark fibroids as well as upon completion of the learning curve.