MR-guided focused ultrasound surgery is a safe, effective treatment for uterine fibroids. The number and size of fibroids do not affect outcome, according to a pair of studies presented at the 2005 RSNA meeting.
MRgFUS, also called focused ultrasound surgery, is a promising noninvasive approach to uterine fibroid management. The thermal ablation technique uses ultrasound beams to cut off the tumor blood supply and reduce fibroid volume. Ablation effects are determined in real-time, based on thermal measurements.
In one trial involving 160 women, focused ultrasound surgery proved effective at three-month intervals, from baseline up to one year after the procedure, according to Dr. Fiona Fennessy, a radiologist at Brigham and Women's Hospital in Boston. Researchers used two different protocols in the study. One group of 96 patients had a maximum treatment time of two hours and a maximum treatment volume of 100 cc (6 cm diameter). In the second group of 64 women, researchers used an optimized protocol, with maximum treatment time of three hours and maximum treatment volume of 150 cc (7 cm diameter).
The second, less restrictive protocol was made possible by new research guidelines from the FDA. For patients treated outside the research environment, guidelines are even less restrictive, Fennessy said.
As expected, the optimized protocol yielded better results. One year after MR-guided focused ultrasound surgery, treatment was effective in 75.8% patients in the first group and 85.7% of patients in the second, optimized protocol group.
"The more volume we can treat, the greater symptomatic relief from uterine fibroid symptoms the patient gets," Fennessy said.
VOLUME EFFECT
In another study presented at the meeting, Fennessy's group tested the hypothesis that the number of fibroids and uterine volume affect MRgFUS outcomes. The researchers performed a retrospective review of 51 consecutive patients. They defined treatment success as a 10-point improvement in symptom severity scores, based on a standard patient questionnaire. Uterine volume was calculated from three plane measurements. Of the 51 patients, 45% had one fibroid and 55% had more than one fibroid. The mean number of fibroids was 2.2.
Results were positive for the patients generally: 90% showed a 10-point improvement on a symptom severity questionnaire six months after baseline, while 78% reported improvement at 12 months. There was no connection between the volume of the fibroid and success of the procedure.
Researchers concluded that the number of fibroids and volume are not related to MRgFUS outcomes. Therefore, patients with a large uterus and/or multiple fibroids should be included in screening for MRgFUS, Fennessy said.
