Jean-Yves Chapelon, Ph.D
Directeur de Recherche
INSERM Unite 281
Lyon Cedex03 - France
Therapy with High-Intensity Focused Ultrasound
High-power ultrasound beams may be focused at depth within the body, thereby producing irreversible tissue damage (ablation) lying within the focal volume, with no damage to any structures lying in the path of the beam. With High Intensity Focused Ultrasound (HIFU), tissue temperature in the focal area is elevated within a few seconds to 70-90°C, which results in tissue necrosis in a very short time. The slightly conical form of the lesion achieved is due to the absorption of the ultrasound wave by the tissues, increased by cavitation bubbles. The concept of HIFU was first proposed in the 1940s as a possible tool for neurosurgical research and was intensively developed by the Fry brothers in the1950s. However its potential for more widespread clinical use was not exploited at that time, probably because of the lack of facilities for providing precise visualization and localization of the damage. The tremendous progress in engineering and sciences coupled with ultrasound transducer technology and imaging modalities during the last 10 years has encouraged a revival of clinical interest of ultrasound therapy, and applications in ophthalmology, urology and oncology are currently being developed. So far, the most extensive clinical results were obtained in urology where transrectal prostate HIFU ablation appears to be an effective therapeutic alternative for patients with benign (BPH) or malignant prostate tumors.