High-energy shockwaves and extracorporeal high-intensity focused ultrasound.
We review the physical interactions of focused ultrasound with tissue, describe technical features of current high-energy shockwave (HESW) and extracorporeal high-intensity focused ultrasound (HIFU) devices, and summarize the experimental and human data available to date. Tissue destruction by extracorporeal HIFU is not new: the first clinical attempts were made almost half a century ago for ablating brain tissue. Despite recent progress in the knowledge of the interactions between HIFU and tissue and significant device modifications, this technique is still in its infancy. The most promising targets for this kind of therapy in the field of urology are the kidney, bladder, and testis. The largest clinical experience with HIFU therapy currently available is for benign prostatic enlargement and prostate cancer using transrectal HIFU devices, which are not the topic of this summary. In parallel with HIFU, HESW therapy has been tested in numerous experimental and preclinical settings. This technique is currently not in routine clinical use. Theoretically, in parallel with HIFU, any organ accessible to conventional diagnostic ultrasound examination is a potential target for this kind of therapy.