Histotripsy

High-intensity focused ultrasound (HIFU) is a non-invasive therapeutic technique that uses non-ionizing ultrasonic waves to heat tissue. HIFU can be used to increase the flow of blood or lymph, or to destroy tissue, such as tumors, through a number of mechanisms. The technology can be used to treat a range of disorders and as of 2015 is at various stages of development and commercialization. High-intensity focused ultrasound (HIFU) is a non-invasive therapeutic technique that uses non-ionizing ultrasonic waves to heat tissue. HIFU can be used to increase the flow of blood or lymph, or to destroy tissue, such as tumors, through a number of mechanisms. The technology can be used to treat a range of disorders and as of 2015 is at various stages of development and commercialization. The technology is similar to ultrasonic imaging, although lower frequencies and continuous, rather than pulsed waves are used to achieve the necessary thermal doses. However, pulsed waves may also be used if mechanical rather than thermal damage is desired. Acoustic lenses are often used to achieve the necessary intensity at the target tissue without damaging the surrounding tissue. An analogy is using a magnifying glass to focus sunlight; only the focal point of the magnifying glass has high intensity. Although lenses have traditionally been used, phased arrays are increasingly common as they allow the focal position to be easily changed. HIFU may be combined with other imaging techniques such as medical ultrasound or MRI to enable guidance of the treatment and monitoring. There is no clear consensus on the boundaries between HIFU and other forms of therapeutic ultrasound. In academic literature, HIFU usually refers to the high levels of energy required to destroy tissue through ablation or cavitation, although it is also sometimes used to describe lower intensity applications such as occupational therapy and physical therapy. Either way, HIFU is used to non-invasively heat tissue deep in the body without the need for an incision. The main applications are the destruction of tissue, increasing perfusion and physical therapy. The use of ultrasound in the treatment of musculoskeletal conditions is another use in the physiotherapy setting. A focused ultrasound system is approved in Israel, Canada, Europe, Korea and Russia to treat essential tremor, neuropathic pain, and Parkinsonian tremor. This approach enables treatment of the brain without an incision or radiation. In 2016, the US Food and Drug Administration (FDA) approved Insightec’s Exablate system to treat essential tremor. Treatment for other thalamocortical dysrhythmias and psychiatric conditions are under investigation. Treatment for symptomatic uterine fibroids became the first approved application of HIFU by the US Food and Drug Administration (FDA) in October 2004. Studies have shown that HIFU is safe and effective, and that patients have sustained symptomatic relief is sustained for at least two years without the risk of complications involved in surgery or other more invasive approaches. Up to 16-20% of patients will require additional treatment. HIFU is being studied in men with prostate cancer. HIFU has been successfully applied in treatment of cancer to destroy solid tumors of the bone, brain, breast, liver, pancreas, rectum, kidney, testes, prostate.