Uterine Leiomyomas: MR Imaging–guided Focused Ultrasound Surgery—Imaging Predictors of Success

Abstract

Purpose:To retrospectively assess the magnetic resonance (MR) imaging predictors of success at reducing uterine leiomyoma volume and achieving patient symptom relief 12 months after MR imaging-guided focused ultrasound surgery. Materials and Methods:This single-center retrospective analysis of 71 symptomatic fibroids in 66 women was approved by the institutional review board and was HIPAA-compliant. Patients were treated with MR imaging-guided focused ultrasound surgery. The volume of treated fibroid and nonperfused volume (NPV) were calculated with software, while symptom outcome was assessed with a symptom severity score (SSS). Fibroids were classified as hyperintense or hypointense relative to skeletal muscle on pretreatment T2-weighted MR images. Results:Baseline volume of treated fibroids was 255.5 cm 3 Ϯ 201.7 (standard deviation), and baseline SSS was 61.5 Ϯ 14.9. Both pretreatment fibroid signal intensity (SI) and posttreatment NPV predicted 12-month volume reduction independently: Fibroids with an NPV of at least 20% or with low SI both showed significantly larger volume reduction (17.0% Ϯ 13.0 and 17.2% Ϯ 20.1, respectively) than fibroids with an NPV less than 20% or with high SI (10.7% Ϯ 18.2 and no significant change, respectively). Patients whose fibroids demonstrated an NPV of at least 20% also experienced a larger decrease in SSS than did patients with fibroids with an NPV less than 20% (50.1% Ϯ 19.8 vs 32.6% Ϯ 29.9). Conclusion:Fibroids with low SI on pretreatment T2-weighted MR images were more likely to shrink than were ones with high SI. The larger the NPV immediately after treatment, the greater the volume reduction and symptom relief were. These findings may help both in selecting appropriate patients for MR-guided focused ultrasound surgery and in predicting patient outcome.

Clinical applications of high-intensity focused ultrasound

“…100,101 Extracorporeal HIFU enables ablation of various sizes and shape of fibroid. Symptoms are reduced by more than 50% in terms of pain, [102][103][104] bulk-related and menstrual symptoms, comparable with the results of conventional surgery. 105 After HIFU, the ablated fibroid volume is decreased, and is related to the non-perfused volume of the tumour immediately after treatment.…”

An Update on Magnetic Resonance Guided Focused Ultrasound Surgery (MRgFUS) of Uterine Fibroids

“…A very recent study has determined that older patients (mean age 46) were more likely to be associated with long-term treatment success [30]. We and others [30,31] have also shown that fibroids of low SI on pretreatment T2-weighted MR images are more likely to decrease in size post-MRgFUS compared with more cellular fibroids of high SI on T2 WI.…”

Dynamic contrast-enhanced MRI serves as a predictor of HIFU treatment outcome for uterine fibroids with hyperintensity in T2-weighted images

“…Lénárd et al (8) and Funaki et al (9) have observed that the NPV ratio of hyperintense uterine fibroids is reduced compared with that of hypointense and isointense fibroids; therefore, HIFU may not be an appropriate treatment method for hyperintense fibroids. However, the results of the present study indicated that the majority of hyperintense uterine fibroids may be eligible for HIFU ablation, based on the technical success of the present procedures.…”

“…Fibroids are defined as hyperintense if their pretreatment signal intensity appears to be equal to or greater than the surrounding myometrium under T2-weighted MRI. Previous studies (8,9) have observed that hyperintense fibroids exhibit a smaller average NPV and lower regression rates compared with isointense or hypointense fibroids following HIFU ablation. Therefore, hyperintense fibroids should be exempted from this procedure.…”