Forever blowing bubbles

In collaboration with the Press Association

Tiny bubbles of gas could be used to block the flow of blood to tumours in a pioneering technique, according to research published in the Journal of Biomechanical Engineering

Tackling tumours by cutting off their supply of nutrients - a process known as embolisation - is a promising area of cancer research.

A major difficulty is getting some form of blockage into the required spot, however, as the surgery required is often extremely invasive.

The researchers, from the University of Michigan in the US, believe that bubbles may be an answer to this, as they can be delivered directly and then expanded where they are needed from outside the body.

They are developing a system that will allow droplets to be injected into the body and monitored by ultrasound scans as they travel through the blood stream.

Once they reach the required spot, doctors should be able to "trigger" them with a beam of high-intensity ultrasound, causing them to expand into a bubble around 125 times bigger.

"If a bubble remained spherical its diameter would be much larger than that of the vessel," said lead researcher, assistant professor Joseph Bull.

"So it deforms into a long sausage-shaped bubble that lodges in the vessel like a cork.

"Two or three doses of bubbles will occlude [block] most of the [blood] flow. Without blood flow, the tumour dies."

The technique could be very valuable in treating certain cancers, such as liver cancer.

Cirrhosis of the liver makes it difficult to treat by the conventional method of removing the tumor and surrounding tissue, because so much of the liver is already damaged.