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

Abstract

K E Y W O R D S:focused ultrasound surgery; magnetic resonance imaging; non-perfused volume; uterine fibroid learning curve ABSTRACTObjectives 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 nonperfused volume (NPV) ratio in 287 Japanese

Magnetic Resonance Imaging–Guided Focused Ultrasound Treatment of Symptomatic Uterine Fibroids

“…20 This NPV ratio has been shown to be a predictor of both fibroid volume and symptom reduction, 11,23 which suggests a strong correlation between the success of MRgFUS treatment and devascularization, as has been suggested in uterine fibroid embolization. 24 Early clinical studies conducted before FDA approval of the first-generation ExAblate 2000 system were limited by several restrictive safety measures to minimize the likelihood of adverse events.…”

“…The recent work by Okada et al 20 has underlined the impact of the learning curve on the technical outcome and complication rates of MRgFUS over time. Their retrospective evaluation included 287 patients who underwent treatment of uterine fibroids with ExAblate 2000 in 4 different Japanese institutions over a 4-year period.…”

“…23 The 3-dimensional planning software introduced with the second-generation ExAblate 2100 system, used in our study, automatically generates a plan that enhances the NPV, through the use of angled ultrasound beam targeting, optimization of the spot energy and distribution, adequate packing of the planned sonications, and ablation of all accessible fibroid regions. 20 However, there are still various patient-and fibroid-related factors that may negatively influence the eligibility and accessibility of patients, and affect the technical outcome of the MRgFUS procedure, or require particular mitigation techniques before treatment.…”

MR-guided high-intensity focused ultrasound treatment of uterine fibroids

“…29 Scarring of the abdominal wall, eg, after cesarean section or laparatomy, might be the relative contraindications of MR-HIFU as far as it could not be bypassed by the ultrasound beam through dynamic focusing or movement of the HIFU probe. 30 As there is the possibility of nerve damage, close allocation of the treated uterine fibroid next to the lumbar plexus should raise an enhanced level of attention. As the MR-HIFU beam is capable to propagate through tissues to a maximum depth of 14 cm, UFs allocated deeper than 14 cm from the abdominal surface could not be reached.…”

“…Here, decision for HIFU therapy has to be made on a case-by-case basis (Table 2). 30,48 Postinterventional abdominal discomfort, sciatic nerve paresthesia or simply leg pain, and slight skin burns of the abdominal wall are the commonly reported side effects of MR-HIFU treatment (Table 3). Only one case of severe skin burns that needed surgical intervention after MR-HIFU treatment is reported, further underlining the noninvasiveness of this method.…”