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OBJECTIVES: To assess the safety and feasibility of MRI-guided high-intensity focused ultrasound (MR-HIFU) ablation in breast cancer patients using a dedicated breast platform. METHODS: Patients with early-stage invasive breast cancer underwent partial tumour ablation prior to surgical resection. MR-HIFU ablation was performed using proton resonance frequency shift MR thermometry and an MR-HIFU system specifically designed for breast tumour ablation. The presence and extent of tumour necrosis was assessed by histopathological analysis of the surgical specimen. Pearson correlation coefficients were calculated to assess the relationship between sonication parameters, temperature increase and size of tumour necrosis at histopathology. RESULTS: Ten female patients underwent MR-HIFU treatment. No skin redness or burns were observed in any of the patients. No correlation was found between the applied energy and the temperature increase. In six patients, tumour necrosis was observed with a maximum diameter of 3-11 mm. In these patients, the number of targeted locations was equal to the number of areas with tumour necrosis. A good correlation was found between the applied energy and the size of tumour necrosis at histopathology (Pearson = 0.76, p = 0.002). CONCLUSIONS: Our results show that MR-HIFU ablation with the dedicated breast system is safe and results in histopathologically proven tumour necrosis. KEY POINTS: • MR-HIFU ablation with the dedicated breast system is safe and feasible • In none of the patients was skin redness or burns observed • No correlation was found between the applied energy and the temperature increase • The correlation between applied energy and size of tumour necrosis was good.

MRI is increasingly used in breast cancer patients. MRI has a high sensitivity compared to mammography and ultrasound. The specificity is moderate leading to an increased risk of false positive findings. Currently, a beneficial effect of breast MRI has been established in some patient groups and is debated in the general breast cancer population. The diagnostic ability of MRI and its role in various groups of breast cancer patients are discussed in this review. J. Surg. Oncol. 2014 110:26–31. © 2014 Wiley Periodicals, Inc.

This chapter describes several aspects of MR-HIFU treatment for breast cancer. The current and future applications, technical developments and clinical results are discussed. MR-HIFU ablation is under investigation for the treatment of breast cancer, but is not yet ready for clinical implementation. Firstly, the efficacy of MR-HIFU ablation should be investigated in large trials. The existing literature shows that results of initial, small studies are moderate, but opportunities for improvement are available. Careful patient selection, taking treatment margins into account and using a dedicated breast system might improve treatment outcomes. MRI-guidance has proven to be beneficial for the accuracy and safety of HIFU treatments because of its usefulness before, during and after treatments. In conclusion, MR-HIFU is promising for the treatment of breast cancer and might lead to a change in breast cancer care in the future.

The T-1 and T-2 temperature dependence of female breast adipose tissue was investigated at 1.5 T in order to evaluate the applicability of relaxation-based MR thermometry in fat for the monitoring of thermal therapies in the breast. Relaxation times T-1, T-2 and T-2TSE (the apparent T-2 measured using a turbo spin echo readout sequence) were measured in seven fresh adipose breast samples for temperatures from 25 to 65 degrees C. Spectral water suppression was used to reduce the influence of the residual water signal. The temperature dependence of the relaxation times was characterized. The expected maximum temperature measurement errors based on average calibration lines were calculated. In addition, the heating-cooling reversibility was investigated for two samples. The T-1 and T-2TSE temperature (T) dependence could be fitted well with an exponential function of 1/T. A linear relationship between T-2 and temperature was found. The temperature coefficients (mean +/- inter-sample standard deviation) of T-1 and T-2TSE increased from 25 degrees C (dT(1)/dT = 5.35 +/- 0.08 ms/degrees C, dT(2TSE)/dT = 3.82 +/- 0.06 ms/degrees C) to 65 degrees C (dT(1)/dT = 9.50 +/- 0.16 ms/degrees C, dT(2TSE)/dT = 7.99 +/- 0.38 ms/degrees C). The temperature coefficient of T-2 was 0.90 +/- 0.03 ms/degrees C. The temperature-induced changes in the relaxation times were found to be reversible after heating to 65 degrees C. Given the small inter-sample variation of the temperature coefficients, relaxation-based MR thermometry appears to be feasible in breast adipose tissue, and may be used as an adjunct to proton resonance frequency shift (PRFS) thermometry in aqueous tissue (glandular + tumor). Copyright (c) 2015 John Wiley & Sons, Ltd.

We have recently conducted a clinical phase I study to assess the safety and spatial accuracy and precision of a newly developed dedicated MR-HIFU system for lateral breast tumor ablation [1]. Here, we report on patient inclusion, treatment efficacy and safety.

Early detection and diagnosis of breast cancer are essential for successful treatment. Currently mammography and ultrasound are the basic imaging techniques for the detection and localization of breast tumors. The low sensitivity and specificity of these imaging tools resulted in a demand for new imaging modalities and breast magnetic resonance imaging (MRI) has become increasingly important in the detection and delineation of breast cancer in daily practice. However, the clinical benefits of the use of pre-operative MRI in women with newly diagnosed breast cancer is still a matter of debate. The main additional diagnostic value of MRI relies on specific situations such as detecting multifocal, multicentric or contralateral disease unrecognized on conventional assessment (particularly in patients diagnosed with invasive lobular carcinoma), assessing the response to neoadjuvant chemotherapy, detection of cancer in dense breast tissue, recognition of an occult primary breast cancer in patients presenting with cancer metastasis in axillary lymph nodes, among others. Nevertheless, the development of new MRI technologies such as diffusion-weighted imaging, proton spectroscopy and higher field strength 7.0 T imaging offer a new perspective in providing additional information in breast abnormalities. We conducted an expert literature review on the value of breast MRI in diagnosing and staging breast cancer, as well as the future potentials of new MRI technologies.

correction method was used to correct on-line for respiration-induced magnetic field fluctuations.[2] The performance of the correction method was assessed in absence of HIFU heating. The temporal standard deviation (SD) in temperature maps calculated before and after applying the correction method and the number of dynamics needed before switching to the intervention phase were used as a measure of performance. The targeting accuracy and precision of the system was assessed using MR thermometry data. For each sonication the trajectory of the center of mass of the heating pattern in the focal area over time was calculated. The standard deviation of the distribution of the distances between the center of mass in time and the mean center of mass was defined as precision. The distance between the mean center of mass and the planned treatment position was defined as accuracy.