Next-Generation Medical and Therapeutic Ultrasound: From rewarming to neuromodulation and thermal ablation

Ultrasound is widely known for its therapeutic and medical uses, particularly its ability to heat tissues to treat cancerous tumours and essential tremor. The success of these applications may be due to their flexible operational parameters, allowing for somewhat variable rates of tissue heating. However, emerging ultrasound applications, such as rewarming of biological cells and tissues after cryopreservation, require much tighter control over acoustic and thermal conditions to be successful. In rewarming, precise control of heating rate and spatial uniformity of temperature is crucial for preventing thermal stress and ice formation, which is a significant challenge in rewarming larger tissue volumes or organs after storage at low temperatures. Recent results demonstrate the promise of ultrasound for rewarming in various models, including bovine muscle and rat heart, with high warming rates and successful preservation of structure and function, yet challenges remain, especially in scaling up to larger, human-sized organs. Beyond thermal applications, ultrasound shows promise for neuromodulation of the brain for treatment of neurological and psychiatric disorders. To establish thresholds for effect and fully explore its capabilities requires precise targeting and control over the ultrasound field inside the brain. To achieve this, a greater understanding of the interaction of ultrasound with the skull is needed, together with more advanced and efficient computational modelling tools that capture all the physics needed to predict the propagation of ultrasound through solid materials.

The aim of this fellowship is to overcome these challenges by developing advanced tools for measurement and simulation of ultrasound propagation and temperature distributions, and to build comprehensive knowledge of the properties of tissues under relevant conditions. Access to these tools will accelerate the development of ultrasound applications including rewarming after cryopreservation, neuromodulation, and thermal ablation. Our initial work laid a foundation in ultrasonic tissue rewarming, demonstrating the concept, exploring material properties at low temperatures and beginning to address metrology and modelling challenges. The next phase will expand on this, tackling fundamental issues that apply similarly to other uses of ultrasound. This will enhance the efficacy and adoption of therapeutic and medical applications of ultrasound such as rewarming, which has the potential for broad impact in tissue transplantation, regenerative medicine, and tissue engineering; ultrasonic neuromodulation which could offer a non-invasive, drug-free alternative for treatment of neurological and psychiatric conditions; and high-intensity focused ultrasound for treatment of cancer and other disorders. It will also open new avenues for application to other uses, all of which will bring significant societal and economic benefits, improving health and quality of life.