For decades, ultrasound energy has been used to safely view the interior of the body without exposing patients to the risks associated with radiation. An important difference between ultrasound 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. For this reason ultrasound has been widely used as a diagnostic tool. It has also come into use at a high, concentrated power in both therapeutic and surgical applications.
Medical ultrasound is a high frequency mechanical wave that moves matter slightly as it passes, compressing and expanding tissue millions of times a second. Heat is generated by the process because all materials absorb a tiny fraction of the energy carried by the ultrasonic wave through friction of motion, and at very high powers this absorption can lead to a dramatic rise in temperature. The heat generated by ultrasound waves can be used to destroy tissue. Focused Ultrasound (FUS), or High Intensity Focused Ultrasound (HIFU), is now being used as a non-invasive surgical procedure to destroy diseased tissue. One big advantage of this focused use of sound waves is that it allows for the pathological tissue to be destroyed while at the same time preserving the normal tissues surrounding it.
Focused Ultrasound surgery (FUS) is a highly precise procedure using focused ultrasound to heat and destroy diseased tissue. 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.
In focused ultrasound therapy, Ultrasound beams are focused on diseased tissue, and due to the significant energy deposition at the focus, temperature within the tissue rises to more than 65°C, destroying the diseased tissue. This technology can achieve precise "ablation" of diseased tissue, therefore being called focused ultrasound surgery.
Development of focused ultrasound 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).
MRgFUS describes the clinical application of FUS (focused ultrasound) using MRI 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.
Development of this therapy significantly broadened the range of treatment options for patients suffering from uterine myoma (fibroids). MRgFUS offers patients with a non-invasive alternative to surgery. It requires only a short period of hospitalization and has a low complication rate.
MRgFUS has received CE marking and FDA approval for treatment of uterine myoma (fibroids). This non-invasive treatment is currently available to women in the US, UK, Germany, Japan, Hungary and Israel. Clinical trials are underway to evaluate MRgFUS treatment of cancerous tumours in the brain, liver, bone and breast.