The Ultrasound and the Flurry
Researchers consider pumping up the volume on imaging test
TUESDAY, Sept. 25, 2001 (HealthDayNews) -- In the world of medical procedures, ultrasound is about as safe as it gets. A machine sends high-pitched sound waves into your body, detects them as they bounce back from your insides, and creates a moving picture of a heart, a lung or a fetus. But scientists say the grainy images aren't good enough, and they are turning to animals to find out if they can safely turn up the volume.
The results are promising, say researchers in Illinois who pumped up the power of ultrasound machines on mice, rats, rabbits and pigs with only minor side effects.
"It's telling us that we might be able to go to higher levels," says lead researcher William O'Brien Jr., an engineering professor at the University of Illinois at Urbana-Champaign.
Ultrasound, which works like radar, has been around for nearly 40 years. Unlike X-rays, ultrasound shows moving pictures and doesn't involve radioactivity, O'Brien says.
The public is perhaps most familiar with its use on pregnant mothers. By using ultrasound, doctors can detect health problems in fetuses and tell parents the gender of their unborn children.
"You have to remember that before ultrasound came along, the obstetrician never looked at an [X-ray] image of the fetus. It was just counter-indicated," except in rare cases, due to radiation risks, " O'Brien says.
Other ultrasound uses are not so well known. Emergency room doctors use ultrasound to glimpse internal injuries after an accident or act of violence, and cardiologists use it to look at the heart. "You can watch the movement of the heart, the heart vessels and the valves," O'Brien says.
Ultrasound machines send out bursts of sound at high frequencies that humans cannot hear. The sound bounces back at different times, depending on the densities of tissues they hit, allowing the ultrasound machine to draw a topographical picture of internal organs.
While ultrasound is harmless, more intense sound waves can be used like a "big hammer" to break up unwanted things in the body, such as kidney stones. "We wondered whether there might be the potential for the same type of damage to occur during diagnostic ultrasounds," O'Brien says.
The researchers, who released their findings at a meeting of the International Congress on Acoustics earlier this month in Rome, found tiny hemorrhages -- incidents of bleeding -- in the lungs. But O'Brien says the problem is actually quite minor, similar to what a person might suffer after a coughing fit. "The concern to the clinician would probably be with patients who already have some predisposition to a lung problem," he says.
Sound waves may actually suck lung tissues outward as they bounce off them, says Christy Holland, a professor of biomedical engineering and radiology at the University of Cincinnati who studies ultrasound. But the effects aren't huge, she says.
"The amount of blood we look for is quite small. We have to look under a microscope to see it," she says.
For other patients, such as those with cancer, the benefit of a clearer ultrasound image may be worth the risk. If one can go to a higher frequency, one might be able to see a lesion that's smaller than what they can see now," O'Brien says.
Holland says, "The risk of not getting the accurate diagnosis" should also be considered when looking at the hazards.
What To Do
Because the Food & Drug Administration limits the power of ultrasound machines, your doctor can't just pump up the volume, although O'Brien says doctors should get the final say.
Are you facing an ultrasound examination? The American Institute of Ultrasound in Medicine offers a Q&A about what to expect.
Check this ultrasound image of a 12-week-old fetus at Parenthoodweb.com, along with links to other pictures.