UM Researchers Fighting Tumors With....Bubbles?

University of Michigan researchers are using gas bubbles to block the flow of oxygen to tumors, like a cork in a bottle. They can also be used to deliver drugs to tumors. The theory behind this is to create a artificial embolism, or blockade of a blood vessel, referred to as embolotherapy. When this occurs naturally, it usually is the result of coronary disease (cholesterol deposits or blood clots which become dislodged) which can lead to a stroke or aneurysm. By creating an artificial gas-bubble embolism, a doctor is able to carefully control the path of the bubble from the outside with high intensity ultrasound, so the damage is solely focused on the tumor. The damage to surrounding tissue is minimal.

This envisioned technique is actually a two-step process, Bull said. First, a stream of encapsulated superheated perfluorocarbon liquid droplets goes into the body by way of an intravenous injection. The droplets are small enough that they don't lodge in vessels. Doctors image the droplets with standard ultrasound, and once the droplets reach their destination, scientists hit them with high intensity ultrasound. The ultrasound acts like a pin popping a water balloon. After the shell pops, the perfluorocarbon expands into a gas bubble that is approximately 125 times larger in volume than the droplet.

Tao Ye and Joseph Bull. Microbubble Expansion in a Flexible Tube. J. Biomechanical Engineering. Aug 2006. V 128, p554-563.