MR imaging-guided focused ultrasound surgery of fibroadenomas in the breast: A feasibility study

PURPOSE: To test the feasibility of noninvasive magnetic resonance (MR) ima ging-guided focused ultrasound surgery (FUS) of benign fibroadenomas in the breast. MATERIALS AND METHODS: Eleven fibroadenomas in nine patients under local an esthesia were treated with MR imaging-guided FUS. Based on a T2-weighted de finition of target volumes, sequential sonications were delivered to treat the entire target. Temperature-sensitive phase-difference- based MR imaging was performed during each sonication to monitor focus localization and tis sue temperature changes. After the procedure, T2-weighted and contrast mate rial-enhanced T1-weighted MR imaging were performed to evaluate immediate a nd long-term effects. RESULTS: Thermal imaging sequences were improved over the treatment period, with 82% (279 of 342) of the hot spots visible in the last seven treatment s. The MR imager was used to measure temperature elevation (12.8 degrees -4 9.9 degreesC) from these treatments. Eight of the 11 lesions treated demons trated complete or partial lack of contrast material uptake on posttherapy ii-weighted images. Three lesions showed no marked decrease of contrast mat erial uptake. This lack of effective treatment was most likely due to a low er acoustic power and/or patient movement that caused misregistration. No a dverse effects were detected, except for one case of transient edema in the pectoralis muscle 2 days after therapy. CONCLUSION: MR imaging-guided FUS can be performed to noninvasively coagula te benign breast fibroadenomas.