The treatment methods associated with high-intensity focused ultrasound, or HIFU, have received increasing interest in recent years, as technology has advanced to a point where the theoretical possibilities of the treatment modality can often be realized in a clinical setting. HIFU allows for a non-invasive, non-ionizing treatment by thermally ablating tissue at a target location while minimally interacting with other tissue. This therapy has the potential to have a dramatic impact on the treatment a variety of conditions and it’s potential for the treatment of cancerous (and benign) tumors is only just starting to be exploited. The most obvious benefit of this novel treatment modality is its ability to destroy undesirable tissue without the risks associated with established therapies such as chemotherapy, surgery or ionizing radiation. In addition, HIFU can be used to enhance drug delivery, typically through the induction of stably cavitating bubbles or through sonoporation, which increases the cell membrane permeability to create a (transient and dynamic) physical route for impermeable agents (such as chemotherapeutic drugs) to enter certain tissue regions. In cardiology and neurology, HIFU also has the, as yet untapped potential, to be used to destroy clots in key blood vessels. Furthermore, it could be used to treat essential tremors and other neurological conditions through targeted lesions in specific areas of the brain. HIFU can also be used as a palliative to alleviate pain by ablating nerve endings in affected regions of the human body.

However, while some HIFU treatment modalities are already used in clinical practice and many others are in the midst of clinical trials, the field (in general) is in need of increased interaction and synergy between clinicians, basic scientists and mathematical scientists. The problem of treatment planning is one rife with complexities which requires advanced modeling techniques in order to compute the acoustic, thermal, and dose fields required to accurately calculate the effects of HIFU therapy. Patient tissue, is an inhomogeneous, heterogeneous moving region for which we often lack physically accurate parameter values. The methods for modeling the way in which these fields interact with the domain are often highly simplified - for example, the thermal dose, measuring the effect of the temperature on the biological tissue, is based on empirical data from the 1940s, which neglects most of the important biological processes and considers temperatures lower than that encountered in many modern HIFU treatment protocols. In cases of high acoustic pressure, cavitation bubbles may form in the tissue, which can both damage the surrounding tissue and defocus the ultrasound beam. These bubbles significantly complicate the modeling effort, but they are sometimes a desirable part of the treatment method or may even be introduced intentionally in the form of microbubbles. Conversely, mathematicians need the guidance of clinicians and basic scientists to properly direct their modeling towards informing future medical developments and considering clinically important issues.

This workshop brings together a balanced international group of both mathematicians and experimental/clinical scientists working clinically, experimentally and theoretically at the forefront of high-intensity focused ultrasound research. The topics covered will span a broad spectrum of problems of current interest in clinical applications of HIFU and will hopefully aid in further cooperation between the groups in order to combine their strengths in tackling this important field.