High Intensity Focused Ultrasound (HIFU) in urology.

Introduction: Focused ultrasound is now well known to urologists in the context of its validated application in extracorporeal lithotripsy. High Intensity Focused Ultrasound (HIFU) represents a potential therapeutic modality for tissue destruction due to its very high energy and its capacity to precisely reach a target with a very short emission time. The authors review the current state of art of HIFU in urology at a time when its indication in prostate cancer is being defined. Material and Method: After a brief description of the main physical principles of ultrasound and the main data determining focussing of high energy ultrasound, the main machines available (research and clinical) are described. The published clinical literature concerning the tissue destructive action in urology is reviewed. Results: HIFU has been used in urology to treat renal, vesical, prostatic (BPH and cancer), and external genital organ lesions. Purely extracorporeal machines are gradually being replaced by intracorporeal procedures, especially transrectal techniques for prostatic lesions. The quality of ultrasound detection of the target still limits the use of this minimally invasive modality. The intervening tissues are spared with a good therapeutic efficacy on the target tissues, provided optimal firing parameters are used. Conclusion: HIFU has a demonstrated potential in the treatment of prostate cancer and studies conducted by several teams have defined the technique and its efficacy. Other indications have been studied, but must be validated by further clinical trials. The future will probably see the design of machines adapted to a specific target tissue rather than a single multidisciplinary extracorporeal machine.