February 17, 2005
Ultrasound for Astronauts
Far away from doctors and hospitals, astronauts in space are learning to give themselves checkups using ultrasound.
Science@NASA -- When you hear the word "ultrasound" you probably think of pregnant moms and their babies. Add one more to that list: astronauts.Nobody's pregnant in space, but astronauts onboard the International Space Station (ISS) are using ultrasound, looking inside themselves as part of a NASA project called ADUM, short for "ADvanced Ultrasound in Microgravity."
Dr. Scott Dulchavsky, a surgeon at the Henry Ford Hospital in Detroit, heads the project. His team, which includes co-investigators Doug Hamilton, Shannon Melton and Ashot Sargsyan, of Wyle Laboratories, in Houston, is studying how ultrasound can be used to diagnose medical problems onboard spaceships.
Here on Earth, doctors can look at broken bones with an x-ray machine, they can look for tumors with a CAT scanner, and they can examine your brain with an MRI. None of those bulky instruments is available on any NASA spacecraft.
There is, however, an ultrasound machine onboard the ISS.
Ultrasound offers several advantages: Compared to other diagnostic imaging tools, ultrasound machines are compact and lightweight. This is important on cramped spaceships where every ounce of payload costs money to launch. Furthermore, ultrasound images appear instantly. You don't have to wait for, say, x-ray films to be developed. Got a problem? Ultrasound can find it quickly.
An ultrasound probe works somewhat like radar. It sends high-frequency (megahertz) sound waves into the body. When those waves encounter an organ -- say, the liver -- some bounce back immediately, and some continue, bouncing back when they reach the next organ -- say, the kidney. Because sound waves travel through each organ, or tissue, at a different speed, the probe is able to "see" what the reflected sound waves have found.
Typically, ultrasound has been used to look at internal organs. It's often used to examine fetuses. But Dulchavsky and his team have been expanding its repertoire. They're working out ways to look at eyes, teeth, lungs, bones and muscles. They believe that ultrasound can be used for about two-thirds of a list of approximately 500 medical conditions that might hypothetically occur on a spacecraft.
And, in some cases, ultrasound works even better in space than it does on Earth. That's because in low gravity, internal organs move around. "The heart shifts up. . . . The liver moves about three inches north." The result is that organs often end up closer to each other. That's good. Sound waves move from one to the other with less distortion, providing a clearer ultrasound picture.
Traditionally, ultrasound probes are operated by technicians with several hundred hours of training. Astronauts only get about four hours training. How do they manage? "We're helping them," says Dulchavsky. As the astronauts work the probe, they're in constant contact with experts on the ground.
Recently, the procedure was tested with ISS astronauts Mike Fincke and Gennady Padalka. The ground crew and the astronauts relied on a satellite downlink to share information. "[Mike] puts the probe to the skin, and then, two seconds later we in the Johnson Space Center get to see the same image he sees," says Dulchavsky.
It's an interactive process: "We go, 'Mike, that's not quite right. Can you move the probe an inch closer to the elbow?' So, Mike slides it down an inch closer. 'Ah, that's really good, you need to push harder.' Mike pushes harder. 'Almost perfect, move it half-an-inch to the back. Ahh, you've got it. Perfect!'"
This technique, non-doctors using ultrasound to obtain diagnostic quality pictures under the guidance of remote experts, turns out to have important applications on Earth -- on battlefields, for instance, or in rural areas where doctors are far away.
"We're looking at modifying how we transmit the information, so we could do it through a cellphone," says Dulchavsky. Picture this: "we could put ultrasound probes on ambulances." Emergency room doctors could set up a treatment before the patient even arrives at the hospital.
The process has already been used successfully on the ground -- in the locker room of the Red Wings, Detroit's hockey team. "Players get hurt a lot in NHL games," says Dulchavsky, a fan. "Last season, we trained one of their trainers to use the probe. It worked famously."
It works well in space, too. In the ISS experiment, Fincke and Padalka examined each others' shoulders. That joint was picked, says Dulchavsky, because it's so complicated. And, even though the shoulder is one of the most challenging ultrasound examinations to do, the astronauts were able to obtain clear, diagnostic-quality views.
A paper describing the procedure was published in the February issue of the journal Radiology; it's the first article ever submitted from orbit.
Right now, Dulchavsky and his colleagues are analyzing their data. The next step, he says, is to put together a program that will teach the astronauts to do more and more on their own. This would enable ultrasound to be used even on long-range exploration missions, like trips to Mars, where guidance from the ground is less practical.
The ADUM project is significant, says Dulchavsky, because it has pushed the limits of what ultrasound technology can do. He and his colleagues plan to push those boundaries even more.
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