Magnetic Resonance-Guided High-Intensity Focused Ultrasound (MR-HIFU): Overview of Emerging Applications (Part 2).

Background High-intensity focused ultrasound (HIFU) allows noninvasive heating of deep-seated tissues. Guidance under magnetic resonance imaging (MR-HIFU) offers spatial targeting based on anatomical MR images as well as MR-based near-real-time temperature maps. Temperature feedback allows delivery of a well-defined thermal dose enabling new applications such as the ablation of malignant tissue. Methods Peer-reviewed publications on MR-HIFU were studied and are summarized in this review. Literature was restricted to applications in oncology. Results Several MR-HIFU-based applications for the treatment of malignant diseases are currently part of clinical trials or translational research. Recent trials regarding the treatment of prostate cancer with MR-HIFU have already shown this to be a safe and patient-friendly method. For the treatment of breast cancer and malignancies within abdominal organs, MR-HIFU has been applied so far only in proof of concept studies. Conclusion MR-HIFU is currently being investigated for the ablative treatment of malignant tissue in a variety of oncological applications. For example, the transrectal as well as transurethral ablation of prostate cancer using MR-HIFU was shown to be a patient-friendly, safe alternative to other local treatment options with low side effects. Key points: MR guidance offers high soft tissue contrast for treatment planning, near-real-time temperature monitoring, and post-interventional therapy evaluation. Special HIFU transducers and technological solutions are available for the treatment of e.g. prostate cancer, breast cancer or abdominal malignancies.