Magnetic Resonance (MR) Guided Focused Ultrasound Surgery of Uterine Fibroids

Background

General:

Uterine leiomyoma (fibroids) are the most common neoplasms of the female pelvis. These benign tumors are generally oval in shape, and often highly vascular. On T2 weighted MR imaging exams, or T1 exams with contrast, uterine fibroids are easily identifiable. They occur in 20-25% of women of reproductive age and can cause a variety of problems generally described as either bleeding or mass effects from the fibroid. In general, these symptoms can be classified into two categories:

1. heavy menstrual bleeding, defined as bleeding on heavy days requiring a change of sanitary wear every 2 hours or less, significant clot passage, flooding, substantial prolongation of menstrual periods compared with the patient's prior experience, or anemia.
2. pelvic pain or pressure, heaviness or discomfort, or similar symptoms in the back, flank or leg attributable to the bulk of the fibroid, urinary frequency, increase in nocturia, difficulty voiding or compression of the ureters with hydronephrosis.

Measures of the clinical success of patients who elect treatment of fibroids are generally subjective, and evaluated by the patient in terms of improvement in the initial symptoms that caused her to seek treatment (decrease in pain, bladder or bowel symptoms, or reduction in vaginal bleeding), while experiencing a minimum of co-morbidities from the treatment itself.

ExAblate Device:

The InSightec ExAblate MR guided Focused Ultrasound Surgery (MRgFUS) system is a non-invasive thermal ablation device fully integrated with an MR imaging system and used for the ablation of soft tissue. It has been evaluated in an earlier FDA international, multi-center study and found to be safe and effective for the treatment of uterine fibroids. ExAblate device received FDA approval in October 2004.

Prior Studies:

The ExAblate has been used for the treatment of uterine fibroids in 2 previous IDE protocols.

• Group A: This was the original Pivotal Study Group (IDE G020001 - Protocol UF002). These 109 patients were treated at 3 sites in the US and at 4 sites outside the US. There was a limitation on the allowable treatment volume and only a single treatment was permitted. Original follow-up was planned for 6 months. The study was later extended to include follow-up visits at 12, 24, and 36 months (UF009). Because of the gap between the initial study consent, and the re-consent for the long term follow-up there was a high dropout rate at the 12 month visit. Thirty-three US patients returned for the 12 months visit, and will continue to be followed for the 24 and 36 M visits.
• Group B: This was the Continued Access Study (IDE G020001 - Protocol UF005) where approximately 160 patients were treated at 3 sites in the US during the PMA review period. Treatment conditions were modified somewhat from the pivotal, including the addition of a second treatment session where necessary. The initial study was planned to include a long term follow-up of 12, 24 and 36 months (UF009).
• Group C: This group of 70 patients (UF14) will be treated post-PMA approval following the commercial treatment guidelines. The follow-up will include for visits at 12, 24 and 36 months. This group includes also another 20 patients who will be treated under this original IDE to validate the ExAblate system for use in a 3T MR scanner, as well as validating a new application SW (V4.1).