Purpose: To evaluate capability of MRIgFUS to ablate single, primary non-metastatic breast neoplasms in patients scheduled for routine surgical lumpectomy and to evaluate if a correlation exists between histopathological lumpectomy data and dynamic infusion studies with repect to amount of residual tumor following MRIgFUS.

Methods and Materials: 25 female patients (average age 59.2 yrs)with a core biopsy proven single breast neoplasm (average size 15 mm)were subjected to a local ablative therapy utilizing MRIgFUS prior to undergoing routine surgical lumpectomy. One followup MR exam (standard sequences followed by dynamic infusion study)was performed no earlier than 3 days and no later than 21 days post MRIgFUS prior to surgical lumpectomy. Follwing surgical lumpectomy, the resected specimen was sectioned at 5 mm intervals and quantitative histopathological analysis performed to accurately assess targeting efficiency and amount of tumor necrosis achieved by the MRIgFUS treatment session. Correlation between the histopathological data post lumpectomy and dynamic infusion studies post MRIgFUS was then performed.

Results: Excluding the first two patients in the series who refused to continue after partial treatment (targeting 47%, necrosis 43%), targeting of tumor process averaged 93% (range 70-100%) and tumor necrosis averaged 90% (range 65-100%). Pain associated with the procedure was rated as mild (N=7) and moderate (N=18) and was adequately controlled with intravenous fentanyl citrate and midazolam (average dose 4 mg midazolam; 200ug fentanyl citrate). Three skin burns were recorded in the first 7 patients treated (resected during lumpectomy) but with addition of a skin cooling apparatus no further complications have been recorded in the last 18 patients. A significant correlation (Pr<.0001) was demonstrated between dynamic infusion studies (obtained post MRIgFUS and prior to surgical lumpectomy) and histopathological data with respect to residual tumor following MRIgFUS.

Conclusion: MRIgFUS of breast neoplasms is an accurate, effective and low morbidity method of tumor ablation. Addition of a skin cooling apparatus has virtually eliminated complications associated with the procedure. Dynamic enhancement studies obtained in this Phase 2 study correlate accurately with residual tumor following MRIgFUS treatment and may offer a key element in the decision process to add additional MRIgFUS treatment sessions in an eventual Phase 3 study. (D.G is a consultant for and has received grant support from TxSonics/Insightec, Haifa Israel.)