Focused ultrasound
HIFU (high intensity focused ultrasound) (sometimes also HIFUS)is a highly precise procedure using high intensity, focused ultrasound to heat and destroy pathogenic tissue typically under computerized MRI guidance.
Overview
In HIFU therapy, ultrasound beams are focused on diseased tissue, and due to the significant energy deposition at the focus, temperature within the tissue rises to 85° to 100°C, destroying the diseased tissue by coagulation necrosis. Each "shot" of the beams treats a precisely defined portion of the targeted tissue. The entire therapeutic target is treated by moving the applicator on its robotic arm in order to juxtapose multiple shots, according to a protocol designed by the physician. This technology can achieve precise "ablation" of diseased tissue, therefore being called HIFU surgery. Because it destroys the diseased tissue non-invasively, it is also known as "Non-invasive HIFU surgery". Anesthesia is not required. The treatment can be combined with radiotherapy or chemotherapy.
Uses
Development of this therapy significantly broadened the range of treatment options for patients suffering from uterine fibroids. HIFU treatment for uterine fibroids was approved by the FDA in December 2005. The cost of the treatment currently limit ist more extensive use.
HIFU has been successfully applied in oncology to destroy solid tumors of the bone, brain, breast, liver, pancreas, rectum, kidney, testes, prostate. [1] [2] A lot of the initial studies have been performed by F. Wu and coworkers the Chongqing Medical University, Chongqing , China. At this stage oncologic treatments are still in the investigatory phases as there is a need to enlarge the database about their effectiveness.
Use of MRI
Development of HIFU therapy has been greatly enhanced through the use of Magnetic Resonance Imaging (MRI) to guide and monitor the procedure. This therapy is more accurately called MRgFUS (MR guided Focused UltraSound).
This therapy describes the clinical application of FUS (focused ultrasound) using a high-quality method of medical imaging to guide, monitor, and control the size and location of the therapeutic focal beam. Since FUS works by causing tissue coagulation, optimal control of the treatment can be achieved by monitoring and controlling the temperature. Magnetic resonance imaging (MRI) can be used for both precise imaging and FUS targeting and real time monitoring of temperature making optimal use of these medical developments.
History
The first commercial HIFU machine, called the Ablatherm, was developed by the French company Edap-Technomed and launched in Europe in 2001 after receiving CE approval, bringing a first medical validation of the technology for localized prostate cancer. Comprehensive studies by practitioners at multiple sites using the device have demonstrated clinical efficacy at more than 5 years with limited occurrence of side effects. HIFU treatment of prostate cancer is currently an approved therapy in Europe, Canada, South Korea, Australia and other locations around the world. Clinical trials in the United States are expected to begin in 2006 by at least one company.
Advantages over other techniques
High Intensity Focused Ultrasound is often considered a promising technology within the non invasive or minimally invasive therapy segments of medical technology. HIFU’s capacity to generate in-depth precise tissue necrosis using an external applicator, with no effect on the surrounding structures, is unique. The history of using therapeutic ultrasound dates back to early in the 20th century. Technology has continually improved and additional clinical applications, both diagnostic and therapeutic, have become an integral part of medicine today.
An important difference between HIFU and many other forms of focused energy, such as radiation therapy or radio surgery, is that the passage of ultrasound energy through intervening tissue has no apparent cumulative effect on that tissue.
See also
External links
References
- ^ Use in Urology, many references
- ^ F Wu, Z-B Wang, Y-De Cao, W-Z Chen, J Bai, J-Z Zou and H Zhu. A randomised clinical trial of high-intensity focused ultrasound ablation for the treatment of patients with localised breast cancer. British Journal of Cancer (2003) 89, 2227-2233.[1]