Fibroid Treatments Demystified, Part III: Focused Ultrasound
Among the hysterectomy alternatives available to women with fibroids is the high intensity focused ultrasound approach (HIFU), more specifically identified as Magnetic Resonance Guided Focused Ultrasound (MRgFUS). MRgFUS is a thermoablative technique that destroys fibroids by focusing a high-intensity beam of ultrasound energy on specific tissue.
Performed as an outpatient procedure, the focused ultrasound method is entirely non-invasive: no insertion of a catheter or needle is necessary, and no cutting is involved. The MRgFUS procedure is approved by the FDA for use in premenopausal women with symptomatic fibroids who have completed childbearing. While certain limitations prevent the technique from being widely used or universally appropriate, its effectiveness in reducing symptom severity and improving patients’ quality of life has been demonstrated in a variety of cases.
How Focused Ultrasound Works
MRgFUS is performed without anesthesia, under conscious or no sedation, by a physician, with the patient in an MRI unit. Using magnetic resonance imaging (MRI) allows the practitioner to achieve clear visualization of the reproductive organs and provides real-time thermal monitoring, enabling the practitioner to optimize the ultrasound treatment’s ablative effects. The physician then directs high intensity ultrasound waves to a small area of fibroid tissue, destroying the targeted tissue with thermal energy. The ultrasound beam has a frequency range of approximately 1–1.5 MHz, which is on the low end of the spectrum for diagnostic ultrasonography. Immediately following the treatment, the patient is injected with an MRI contrast agent called gadolinium, which allows the practitioner to view the treatment’s impact on the fibroid’s vascular structure.
Patients who undergo a focused ultrasound procedure typically experience rapid recovery. Symptom improvement is usually seen within the first three months post-procedure, and research has shown this improvement to be sustained through 24 to 36 months in most cases.
While generally effective, focused ultrasound therapy is limited in its usefulness. For example, MRgFUS cannot be performed effectively if certain kinds of structures—such as the bowel, the pelvic bone, a skin fold, or an implanted device — are obstructing the path to the fibroid. Furthermore, characteristics of the fibroids themselves—including size, vascularity, and placement—can sometimes make them difficult to treat. The maximum size treatable is uncertain; however, most practitioners surveyed indicated that fibroids larger than 10cm are generally more difficult to treat with focused ultrasound.
Since focused ultrasound is limited in its ability to target all fibroids, repeated treatments are often required: Stewart et. al found that, “With minimal [initial] treatment the probability of additional treatment exceeds 50% at 24 months, but this is substantially reduced with increasing ablation”.
The MRgFUS procedure is not widely available, mostly due to cost: few clinics are equipped with the high-priced system, and insurers are not typically inclined to cover costly procedures. On the positive side, short-term morbidity is low and the recovery time is short. No specific pattern of complications with pregnancy has been identified; however, the procedure is not indicated for women who plan to get pregnant. For others who are seeking a uterine-sparing, non-invasive treatment to relieve symptomatic fibroids, the focused ultrasound approach may be a viable option.
Stewart, E. et al. “Clinical Benefit of Focused Ultrasonography”, Obstetrics & Gynecology. Aug. 2007; Vol.110(2):279-287
InSightec, “MR Guided Focused Ultrasound for Uterine Fibroids”, Information for Prescribers: ExAblate Version 2.46. Revised Nov. 2004
“HIFU Treatment (High Intensity Focused Ultrasound).” Uterine Fibroids. Retrieved June 26, 2015. http://www.uterine-fibroids.org/hifu.html.