High-intensity focused ultrasound (HIFU)

What is HIFU?

High-intensity focused ultrasound (HIFU) is a non-invasive therapy that uses focused ultrasound waves to thermally ablate a portion of tissue, meaning the tissue is destroyed using intense heat. The intense heat causes tissue coagulation necrosis, cavitation and heat shock in the cells, meaning that the portion of tissue which is being ablated is destroyed.

How does the procedure work?

High power ultrasound can be focused on a targeted point to raise the temperature to 70-80°C.

HIFU uses sonication (sound energy) to create this heat. Each sonication heats only a small focal target, so the interventional radiologist will use multiple sonications to ablate the whole affected area. The interventional radiologist may use diagnostic sonography with focused ultrasound (USgFUS or USgHIFU) or magnetic resonance guidance with focused ultrasound (MRgFUS).

Why perform it?

You may be advised to have the procedure to treat uterine fibroids or to alleviate pain from bone cancer. HIFU can also be used to treat prostate cancer, both as a primary treatment and after radiotherapy.

Investigations into using HIFU to treat liver, breast and brain tumours have had promising results.

Positive results with transcranial MR-guided focused ultrasound surgery (tcMRgFUS) as a non-invasive treatment of essential tremors, neuropathic pain and Parkinson’s disease have been reported in literature. There have also been some investigations into the use of HIFU for temporarily opening the blood-brain barrier, allowing absorption of drugs into the brain.

A minimally invasive catheter-based system designed to ablate heart tissue responsible for atrial fibrillation has been approved for use in Europe and is undergoing an FDA approved trial in the United States.

What are the risks?

The risks of this procedure are related to non-target specific sonification (when tissue surrounding the area being treated is affected by the ultrasound waves). A further possible risk is the incomplete destruction of the lesion due to inadequate heating.

HIFU is not suitable for use in some areas of the body as ultrasound waves have a negative effect on some materials, though your interventional radiologist can avoid these effects by doing the procedure under magnetic resonance imaging.

Bibliography

1. Sanghvi NT. High-intensity focused ultrasound treatment of prostate cancer. J Acoust Soc Am. 2013 Nov; 134(5):4089.
2. Xiaoping L, Leizhen Z. Advances of high intensity focused ultrasound (HIFU) for pancreatic cancer. Int J Hyperthermia. 2013 Nov; 29(7):678-82.