A Review of High-Intensity Focused Ultrasound in Urology

Simple Summary: High intensity focused ultrasound is a novel and non invasive treatment for an increasing number of cancers and benign diseases. The principal is similar to focusing the sun's rays with a magnifying glass, causing a burn at the focal point. This can be done with ultrasound if the usual diagnostic energy is increased 10,000 times. The ultrasound energy is generated under water and the energy passed noninvasively into the body to a sharp focus where it destroys tissue. The technology is rapidly evolving. In urology, trials have been done in a number of areas but the two which are most promising at the present time are for the treatment of renal and prostate cancers. Treatment of renal cancer is currently limited by the position of the kidneys due to the ribs and the presence of perinephric fat, but treatment for prostate cancer is becoming more established.This review provides an introduction to high-intensity focused ultrasound (HIFU) and reviews its historical and current use in urological surgery. Current and historical literature (1927-2020), including that describing trials and review articles in the medical and ultrasonic literature, has been reviewed, using Pub Med and Cochrane search engines. HIFU is currently one of a number of treatments for prostate cancer, both as a primary treatment that can be repeated, and as a salvage treatment post-radiotherapy. HIFU is not yet sufficiently mature to be a standard treatment for renal cancer or other urological diseases, although there has been some success in early clinical trials. As the technology improves, this situation is likely to change. HIFU has been understood as a concept for a century, and has been applied in experimental use for half that time. It is now an accepted treatment with low morbidity in many diseases outside the scope of this review. In urological surgery, prostate HIFU is accepted as a localised treatment in selected cases, with potentially fewer side effects than other localised therapies. Currently the treatment for renal cancer is hindered by the perinephric fat and the position of the kidneys behind the ribs; however, as the technology improves with image fusion, faster treatments, and the ability with phased array transducers and motion compensation to overcome the problems caused by the ribs and breathing, successful treatment of kidney tumours will become more of a reality. In due course, there will be a new generation of machines for treating prostate cancer. These devices will further minimise the side effects of radical treatment of prostate cancer.