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Doing surgery without scalpels, but sound waves

October 28, 2002|Linda Marsa | Times Staff Writer

It sounds like something lifted from "Star Trek": High intensity sound waves are beamed through the skin, enabling doctors to perform surgery without making incisions. But this futuristic scalpel may soon be available in the nation's operating rooms.

Scientists at Indiana University in Indianapolis have devised a tool that uses sound waves broadcast through a specially designed set of speakers to destroy diseased or cancerous tissue. The waves, which are at frequencies too high for people to hear, converge inside the body -- an effect similar to using a magnifying glass to focus the sun's light onto a piece of paper.

"It burns at the focal point," says Narendra Sanghvi, an engineer who helped develop this technology. "Because the energy level is so high, the tissue gets extremely hot in less than a second, and the cells die instantaneously."

The device simultaneously beams lower frequency ultrasound waves to create a three-dimensional picture for doctors, akin to how ultrasound is used today to find tumors or to detect fetal abnormalities. Consequently, the targeted region can be hit with a pinpoint accuracy that rivals the precision of a scalpel, say experts, and doesn't harm the surrounding tissue.

This scalpel-free surgical tool, called the Sonablate 500, may be the first high-intensity focused ultrasound device approved for use in the United States, and is awaiting clearance from the Food and Drug Administration for the treatment of enlarged prostates. In the future, it could be used to remove various types of benign and malignant tumors.

Acoustic surgery, as it is known, has several advantages over conventional surgery, its proponents say. By not breaking the skin, risks of infection are diminished; there's no blood loss so transfusions are unnecessary; patients experience less pain; and recovery time is reduced. "This has a lower complication rate and patients experience less side effects," says Dr. Richard Bihrle, a urologist and member of the Indiana University ultrasound research team.

Indiana University researchers began working on their device in the mid-1980s when ultrasound began to be widely used to dissolve kidney stones. In order to adapt the technique for other types of surgery, however, they needed to monitor exactly what the ultrasound tool was doing to ensure accurate targeting of the beam.

They ultimately invented a machine that can transmit three-dimensional images from deep inside the body at the same time it emits high intensity beams for treatment. This way, doctors get immediate feedback.

What made the technology practical, though, was the discovery the body breaks down and excretes the tissue killed by the sound waves.

"We thought dead tissue had to be surgically removed," says Sanghvi, "but the body's own scavenging system" disposes of the debris.

Since then, they've used their device to reduce swelling in men with enlarged prostates, and are testing it on prostate cancer sufferers. Once this technology becomes widely available, predicts Bihrle, "the potential applications are huge."



Acoustic surgery's possibilities

Acoustic surgery using ultrasound devices is being done in China, Japan and Europe to treat bone, liver, kidney, pancreatic, prostate and liver cancers. In the United States, researchers are experimenting with ultrasound to destroy tumors and to patch leaky blood vessels. Cooking tissue with intense heat triggers the production of bodily chemicals that cauterize wounds.

Harvard University scientists, for instance, are using ultrasound to treat uterine fibroids and to operate inside the skull. Researchers at the University of Washington are doing ultrasound procedures on animals to stop hemorrhages deep inside the body. In the future, this technique may be used to close wounds during surgery, stop the internal bleeding that often kills traffic accident victims, and treat soldiers injured in battle, says Merilee Andrew, an engineer in the University of Washington's Applied Physics Laboratory.

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