Suzanne Denise Leblang MD, Presenter: Nothing to Disclose

The purpose of this retrospective data analysis was to investigate the effects of fibroid characteristics on MRgFUS treatment outcomes. The hypothesis was that MRgFUS treatment would be more successful for certain types of fibroids in terms of the non-perfused volume (NPV) ratio achieved and the efficiency of the treatment.

One hundred eleven women (ages 32-60) with symptomatic uterine fibroids were treated with MRgFUS using the ExAblate 2000 device according to the FDA commercial treatment guidelines. A total of 215 fibroids were treated with MRgFUS. Fibroids were classified by their intensity on T2 weighted images (GE SIGNA 1.5T) relative to the normal myometrium (hyperintense, isointense, hypointense), and consistency of the fibroid (homogeneous, heterogeneous).

The distribution of fibroid intensity was: hyperintense (3.7%), isointense (15.8%), hypointense (78.6%), and unclassified (1.9%). The distribution of fibroid consistency was: homogeneous (56.3%), heterogeneous (40.9%), and unclassified (2.8%). The NPV ratio was calculated as a percent of individual fibroid volume. The average fibroid NPV was 56.9%. The NPV ratio for homogeneous fibroids (61.2%) was greater than that for heterogeneous fibroids (51.6%; p=0.003), and the NPV ratio for hypointense fibroids (61.0%) was greater than that for hyperintense (48.0%) and isointense fibroids (40.9%; p=0.00003). Fewer sonications were required to treat homogeneous than heterogeneous fibroids (p=0.001), and fewer were needed for hypointense than isointense and hyperintense fibroids (p=0.007). The average energy required per sonication was lower for homogeneous than for heterogeneous fibroids (p=0.02), and it was lower for hypointense than for isointense and hyperintense fibroids (p=0.005).

Fibroid image characteristics can predict the success and efficiency of MRgFUS treatment, as indicated by higher NPV ratio achieved with fewer sonications of lower energy, and thus should be considered when assessing patient candidacy for MRgFUS. The ideal fibroid would appear hypointense on T2 weighted images and homogeneous in intensity throughout the fibroid.

Consideration of MRI characteristics of uterine fibroids during patient evaluation and determination of candidacy for MRgFUS treatment could lead to improved treatment outcomes.

Leblang, S, MRI Characterization of Uterine Fibroids to Improve Success and Efficiency of Magnetic Resonance Focused Ultrasound (MRgFUS) Treatment.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8008858.html