ExAblate for Treating Uterine Fibroids


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Magnetic Resonance guided Focused Ultrasound has been demonstrated as a safe and effective option for treating uterine fibroids. Compared to hysterectomy, which is the primary treatment option for uterine fibroids, MRgFUS offers both clinical and economic advantages. Because it is a non-invasive procedure, patients avoid the risks associated with surgery, require only limited conscious sedation, and can return to normal activities the next day compared to lengthy recovery times and hospitalization days required following hysterectomy. 

The ExAblate system was approved by the FDA in 2004 and is the first FDA approved focused ultrasound system. 

Figure 1.  Illustration of a uterus & types of fibroids

Download the treatment options chart

Benefits of Improvements in symptom severity and quality of life/durability

Significant symptom relief is demonstrated almost immediately with women returning home and to normal activities within 1-2 days.
This is measured using the UFS-Quality of Life score, a disease-specific validated measure developed specifically for uterine fibroids1 . It has eight questions that relate to uterine fibroids-specific symptoms: pain, bleeding and bulk. The Symptom Severity Score (SSS) assesses symptoms on a 100-point scale, where higher scores indicate worse symptoms. A typical score for a woman with uterine fibroids is 40 and a typical score for women who do not have (symptomatic) uterine fibroids is 22. An improvement of 10 points is consistent with validation studies for clinical improvement. The UFS-QoL also consists of a second 100-point scale questionnaire that measures six dimensions of health-related QoL. A lower number on this scale indicates an improvement. UFS-QoL was developed with ethnically diverse focus groups to reflect uterine fibroid patients’ views of what symptoms were significant to them.

Studies have shown significant symptom relief in the first three months after the procedure which is sustained for 36 months 2.  At 36 months, the SSS is similar to that of women without uterine fibroids. 

Figure 2.  Mean Symptom Severity Score over time for all patients followed up in clinical trials.  The dashed line represents the mean SSS for women without symptomatic uterine fibroids.

Avoiding the complications and trauma of surgery

The MRgFUS procedure is performed without general anaesthesia. Post-procedural pain is minimal after MRgFUS surgery and managed with OTC medications and complications from the MRgFUS procedure are mild 3 .

Shorter length of stay/ quicker return to normal life and work

MRgFUS is an outpatient procedure, and patients can typically leave hospital one hour after the procedure is completed. 
Main procedure Mean length of hospital stay (days) Length of time to return to normal activity (days)
Hysterectomy8 2.97 32.5-63
Myometcomy9 2.74 12.2-37
Uterine Artery Embolization 1.3 8-28
MRgFUS10 0 4.0-6.6

Table 1.  Length of hospital stay and recovery time

Reduction in days patient unable to engage in usual activities

Data comparing MRgFUS with total abdominal hysterectomy demonstrate that at six months post-treatment, patients undergoing MRgFUS reported fewer days kept from usual activities in the last month due to uterine fibroids or the procedure than patients undergoing total abdominal hysterectomy (see below) and significantly lower use of medical resources. There were 83% fewer provider encounters, 66% fewer additional procedures and 66% fewer additional diagnostic tests in the MRgFUS group compared to the total abdominal hysterectomy group. 10 

Data also indicates, patients undergoing MRgFUS reported fewer lost work days post treatment.

Durability of treatment and retreatment 

There is a close correlation between the percentage of the fibroid treated and the rate of recurrence of symptoms and need for retreatment. The retreatment rate can be predicted by measuring the non perfused volume (NPV) ratio, which measures the extent of treatment by measuring the non perfused volume of the treatment divided by the total fibroid volume (treated and non-treated).
As the NPV ratio increases the retreatment rate goes down.12  Figure 3 shows the probability of undergoing an additional leiomyoma treatment as a function of non-perfused volume ratio, at 12, and 24 months after MRgFUS. At NPV (non-perfused volume) of 60%, the probability of a patient needing to have alternative treatment was 6% at 12 months and 13% at 24 months, which compares favorably with myomectomy and UAE (Uterine Artery Embolization).

Figure 3.  The relationship between NPV ratio and probability of additional treatments for uterine fibroids (Stewart 2007)

At 60% MRgFUS retreatment rates are similar to the retreatment rates of other non-permanent uterine fibroid treatments.
Table 2 below shows retreatment rates for myomectomy, UAE, and MRgFUS from the published literature.

Retreatment rates for uterine fibroids in the published literature

  1 year      2 years      5 years     
Myomectomy 10% 17-20% 17-35%
UAE 7-10% 11-17% 20-29%
MRgFUS 5%* 11%* N/A

Table 2.  Retreatment rates for uterine fibroids
* minimum 60% relative non-perfused volume (from total fibroid load).

Safety / complications

One of the major advantages of MRgFUS is the low rate of adverse events compared to other treatment options. 14
Because of the non-invasive nature of MRgFUS there is a very good safety profile, with relatively few adverse events and morbidity. The incidence of serious adverse events after MRgFUS is low and appears to decrease with increasing physician experience.

1.  Spies J, Coyne K, Guaou Guaou N, Boyle D, Skymarz-Murphy K, Gonzalves S. The UFS-QOL - A New Disease-Specific Symptom and Health-Related Quality of Life Questionnaire for Leiomyomata. Obstet Gynecol. 2002 Feb;99(2):290-300. 
2.  Harding G et al. The responsiveness of the uterine fibroid symptom and health-related quality of life questionnaire. Health and Quality of Life Outcomes 2008,6;99 (12 Nov. 2008)
3.  InSightec semi-annual report to the FDA, June 2008. 
4.  Stewart EA, Gedroyc WM, Tempany CM et al. Focused ultrasound treatment of uterine fibroid tumors: safety and feasibility of a noninvasive thermoablative technique. Am J Obstet Gynecol, 2003;189(1):48-54
5.  Stewart EA, Rabinovici J, Tempany CM et al. Clinical outcomes of focused ultrasound surgery for the treatment of uterine fibroids. Fertil Steril, 2006;85(1):22-29
6. Becker ER, Spalding J, Duchane J, Horowitz IR. Inpatient surgical treatment patterns for patients with uterine fibroids in the United States, 1998-2002. J Natl Med Assoc 2005; 97(10):1336-1342
7. Pron G, Cohen M, Soucie J, Garvin G, Vanderburgh L, Bell S; Ontario Uterine Fibroid Embolization Collaboration Group. The Ontario Uterine Fibroid Embolization Trial. Part 1. Baseline patient characteristics, fibroid burden, and impact on life. Fertil Steril. 2003 Jan;79(1):112-9. 
8. Pron G, Mocarski E, Bennett J, Vilos G, Common A, Zaidi M et al. Tolerance, hospital stay, and recovery after uterine artery embolization for fibroids: the Ontario Uterine Fibroid Embolization Trial. J Vasc Interv Radiol 2003; 14(10):1243-1250
9. Stewart E, et al. Sustained Relief of Leiomyoma Symptoms by Using Focused Ultrasound Surgery, Obstetrics & Gynecology, 2007, 110(2):279-287.
10. Taran, A. et al. Magnetic Resonance Guided Focused Ultrasound (MRgFUS) Compared to Abdominal Hysterectomy for Treatment of Uterine Leiomyomas. Ultrasound Obstet Gynecol, 2009, 34:572-578
11. Stewart EA, Rabinovici J, Tempany CM et al. Clinical outcomes of focused ultrasound surgery for the treatment of uterine fibroids. Fertility and Sterility, 2006;85:22–29
12. Stewart E, et al Sustained Relief of Leiomyoma Symptoms by Using Focused Ultrasound Surgery, Obstetrics & Gynecology, 2007, 110(2):279-287
13. Okada A et al. Non-invasive Magnetic Resonance-guided Focused Ultrasound Treatment of Uterine Fibroids in a Large Japanese Population – The Impact of the Learning Curve on Patient Outcomes. Ultrasound in Obstetrics and Gynecology. 
14. LeBlang SD, et al. Leiomyoma Shrinkage After ExAblate MR-Guided Focused Ultrasound – A Report of 80 Outpatient Commercial Patients, AJR. Jan 2010, 194:274-280 
15. Marret H, Cottier JP, Alonso AM, Giraudeau B, Body G, Herbreteau D. Predictive factors for fibroids recurrence after uterine artery embolisation, BJOG 2005, 112:461-465; 
16. Spies JB, Myers ER, Worthington-Kirsch R, Mulgund J, Goodwin S, Mauro M, The Fibroid Registry: Symptom and Quality of Life satus 1 year after Therapy, Obstet Gynecol, 2005, 106:1309-1318
17. Broder MS, Goodwin S, Chen G. Comparison of long-term outcomes of myomectomy and uterine artery embolization, Obstet Gynecol, 2002, 100:864-868
18. Hanafi M. Predictors of Leiomyoma recurrence After Myometomy, Obstet Gynecol, 2005, 105:877-881.; 
19. Subramanian S, Clark MA, Isaacson K. Outcome and resource use associated with myomectomy, Obstet Gynecol, 2001, 98:583-587.; 
20. Fedele L, Parazzini F, Luchini L, Mezzopane R, Tozzi L, Villa L. Recurrence of fibroids after myomectomy: a transvaginal ultrasonographic study, Hum Reprod, 1995, 10:1795-1796.; 
21. Stewart EH, Faur AV, Wise LA, Reilly RJ, Harlow BL. Predictors of subsequent surgery for uterine leiomyomata after abdominal myomectomy, Obstet Gynecol, 2002, 99:426-432.; 
22. Hutchins FL, Worthington-Kirsch, R, Berkowitz, RP. Selective uterine artery embolization as primary treatment for symptomatic leiomyomata uteri. J Am Assoc Gynecol Laparasc 1999;6 (3):279-284. ; 
23. Doridot V, Dubuisson JB, Chapron C, Fauconnier A, Babaki-Fard K. Recurrence of leiomymata after laparoscopic myomectomy, J. Am. Assoc. Gynecol. Laparosc., 2001, 8:495-500.; 
24. InSightec Ltd. ExAblate 2000 for the treatment of uterine fibroids semi-annual report to FDA, June 2006; 
25. Spies JB, Ascher SA, Roth AR, Kim J, Levy EB Gomez-Jorge J. Uterine artery embolization for leiomyomata. Obstet Gynecol 2001;98(1):29-34; 
26. Stewart EH, Faur AV, Wise LA, Reilly RJ, Harlow BL. Predictors of subsequent surgery for uterine leiomyomata after abdominal myomectomy, Obstet Gynecol, 2002, 99:426-432.

ExAblate for Treating Uterine Fibroids
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