X-rays and CT scans have long been used to diagnose emphysema in people whose coughing and wheezing have prompted them to visit the doctor. But a new imaging technique that uses magnetized helium allows researchers a more detailed view of the lungs than ever before, which could lead to early detection of diseases related to smoking.
According to the American Lung Association, more than 3 million Americans live with emphysema. More than 11,000 adults in Milwaukee County have the disease, and the statewide number jumps above 72,000, according to a recent survey by the National Center for Health Statistics.
The researchers at UW-Madison conducted the study on a group of 19 people ranging in age from 23 to 73. Eight were non-smokers, and 11 were smokers who had no obvious lung damage. While the subjects were inside the tunnel-like magnetic resonance imaging, or MRI, scanner, they were given a small helium-filled bag and asked to take a deep breath through an attached straw. The researchers then took snapshots of the gas when it was in the subjects' lungs.
"Most MRI scans use protons to image, but this is completely different," said Thomas Grist, chairman of UW-Madison's radiology department and a co-author of the study. "The MRI technique that we used measured the diffusion of the gas within the small airways and air sacs."
What interested Grist and others on the research team was how the helium moved once it was inhaled. In a healthy person, the muscular walls of the bronchioles, the tiny airways in the lungs, automatically tighten or relax to control the amount of air entering or leaving the lung.
But in smokers, Grist said, these bronchioles and the alveoli, the air sacs that transfer oxygen to the blood, gradually break down, creating larger spaces in which air can move around. So in the subjects tested, greater movement of the helium molecules indicated that some lung damage was present - damage that an X-ray or CT scan couldn't have picked up.
Once a person begins to have the shortness of breath that characterizes emphysema, the lungs are already fairly weak, said Eduard de Lange, a professor of radiology at the University of Virginia who specializes in lung MRI. De Lange said helium imaging could someday have the same effect as a cholesterol test that persuades someone to radically change his or her diet.
"Studies have shown when you stop smoking, the decline in lung function will slow down," said de Lange. "If you stop smoking, it's not going to improve, but it's going to be less rapid."
The new helium imaging technology won't be available to the public for some time. The research was conducted in partnership with the Milwaukee branch of GE Healthcare, which provided a necessary component called a polarizer. This machine magnetizes the helium, making it "readable" to the MRI scanner.
Grist said future studies using larger groups of research subjects are planned. The results of the study were published in the June issue of the journal Radiology. |
