Focused ultrasound ablation is a noninvasive surgical procedure used to treat pre- or perimenopausal women with symptomatic uterine fibroids who desire a uterus-sparing treatment and who cannot or do not wish to preserve fertility. During this outpatient procedure, the physician delivers focused ultrasound waves to heat and destroy fibroids and spare healthy tissue.
Proponents believe that magnetic resonance guidance provides the following advantages over ultrasound guidance:
- High precision and superior targeting of fibroid tissue
- Three-dimensional imaging of target tissue
- Thermal monitoring in the body
- Clear differentiation between treated and nontreated tissue
- Continuous visualization to ensure that the targeted tumor is fully treated and surrounding tissue is not affected
Appropriate patient selection is important when considering MR-guided focused ultrasound treatment, as numerous labeled absolute and relative contraindications exist, including pregnancy, magnetic resonance-imaging (MRI)-related concerns (e.g., metallic implants, sensitivity to contrast agents), desire for future pregnancy, scar tissue or surgical clips in the potential direct path of the ultrasound beam, fibroid size >10 cm, potential malignancy, and morbid obesity.
Two MR-guided focused ultrasound systems are commercially available to treat fibroids: the ExAblate System (InSightec Ltd, Tirat Carmel, Israel) and the Sonalleve MR-HIFU (high-intensity focused ultrasound) Fibroid Therapy System (Phillips Healthcare, Andover, Md.).
Our key questions and findings are:
1. How does MR-guided focused ultrasound compare to minimally invasive techniques to treat fibroids (i.e., endometrial ablation, myolysis, cryolysis, uterine artery embolization) in terms of symptom severity, quality of life, patient satisfaction, length of hospital stay, need for additional treatment because of recurrence, disability, preservation of fertility, and adverse events?
Our searches identified no studies that addressed this question.
2. How does MR-guided focused ultrasound compare to surgical treatments for fibroids (i.e., laparoscopic, hysteroscopic, or open approaches to myomectomy or hysterectomy) in terms of symptom severity, quality of life, patient satisfaction, length of hospital stay, disability, preservation of fertility, adverse events, and need for additional treatment that is caused by recurrence?
Answering this question is not possible at this time because evidence on the safety and efficacy of MR-guided focused ultrasound is available only on the ExAblate system 2000, and that evidence is of small quantity and low quality. Only one small nonrandomized controlled trial used to obtain premarketing approval is available. That trial compares the procedure to hysterectomy rather than to less invasive options. This study’s design is poor quality because it compares dissimilar patient groups receiving MR-guided focused ultrasound systems or hysterectomy.
3. Is MR-guided focused ultrasound effective in treating fibroids?
The evidence on the efficacy of MR-guided focused ultrasound using the ExAblate 2000 system is of small quantity and low quality. Results of 3 of the 4 small studies that addressed this question reported on symptom severity and suggest that MR-guided focused ultrasound resulted in clinically significant symptom reduction for at least half the patients at 12-month follow-up. About 13 percent of study patients in the four studies required additional treatments for fibroids during 12- to 24-month follow-up.
We did not identify any evidence on the efficacy of MR-guided focused ultrasound using the Sonalleve MR-HIFU system.
4. What adverse events are associated with MR-guided focused ultrasound of uterine fibroids?
The most commonly reported procedure-related complications included skin burns, low back/leg pain, positional back pain, and abdominal pain. Studies reported and classified adverse events in various ways, so calculation of specific adverse event rates was not possible.
The overall incidence of serious adverse events associated with MR-guided focused ultrasound (i.e., sciatic pain, severe abdominal pain, severe burn) was <2 percent in the studies we assessed. No deaths or life-threatening adverse events were reported.
Health facility considerations
Several ongoing clinical trials are expected to provide data on longer-term safety, quality of life, and ability to become pregnant and successfully bear children after the procedure. One ongoing randomized controlled trial that is directly comparing MR-guided focused ultrasound to uterine artery embolization expects to report results in 2012.
Health care facilities must consider several factors, including the following, before acquiring and implementing this technology:
- Competition between specialties to perform the procedure
- Equipment costs
- Available reimbursement
Because gynecologists and interventional radiologists may compete within an institution for the opportunity to perform MR-guided focused ultrasound, hospitals should develop clear policies on who will be granted privileges to perform the procedure.
Clinicians who wish to perform the procedure must obtain manufacturer-sponsored training and certification before their respective institutions install the system and begin treating patients.
Equipment costs vary from $750,000 to $3.5 million, depending on whether the facility already has the required compatible MRI system and on what applications are included in the system.
Strict selection criteria and lack of third-party reimbursement for MR-guided focused ultrasound at this time remain major barriers to widespread adoption and diffusion.