Lasers Detect Disease in Patient Breath
Eric Bland, Discovery News
Feb. 22, 2008 -- Diagnosing life threatening diseases could soon be as easy as breathing.
Researchers at the National Institute for Standards and Technology and the University of Colorado are now using lasers to detect specific chemical compounds in the breath of patients with cancer, asthma and diabetes.
The technique, once perfected and commercialized, could save patients and insurance companies thousands of dollars and make disease diagnosis and monitoring faster and more efficient.
"We hope that the technology will develop to be a very useful tool for preventive medicine," said Jun Ye, a study author and a physics professor at the University of Colorado-Boulder. "It can provide an early warning system to potential patients."
The researchers use a technology known as an optical frequency comb. When a person breathes into a small chamber the scientists bombard the exhaled air with lasers of different wavelengths (making up the "comb"). Different sized laser beams excite specific compounds, which then emit different colors of light. These colors are read by another machine.
In a much simplified version of the technique, the researchers simply look and see what color the breath is after interacting with the comb and then diagnose a condition based on the color.
The laser test, described in the Feb. 18 online edition of Optics Express, is sensitive enough to detect a few molecules out of several billion.
Scientists have known for years that certain diseases and conditions cause minute changes to a person's breath. Diseases cause physiologic changes inside the body, creating new chemical compounds that can either change the chemical composition of the air exiting the lungs, or add new chemicals that aren't found in healthy lungs.
Asthma patients will often exhale carbonyl sulfide, carbon monoxide, hydrogen peroxide and nitric oxide all together. Diabetics often have sweet smelling breath, the result of an inability to process certain sugars.
Even kidney failure and liver disease can change a person's breath at the molecular level. Figuring out the specific biochemical reactions that changes a person's breath is a hot topic of research, notes Ye.
"This is a new kind of non-invasive and shockingly inexpensive assay technique," said John Hall, a retired physics professor whose work with lasers earned him a 2005 Nobel Prize in Physics.
While the device is still being developed, Hall, who was not involved in the work, expects that a commercial version of the device would fit inside an average suitcase and cost between $30,000-50,000.
For his own interest, Hall had the researchers use the device to test his own breath for the presence of nitrate, which can indicate renal failure.
"I was terribly pleased to learn that I don't have it," he said.
lundi, février 25, 2008
This is very cool, but I doubt that the machine is as comforting as the dogs that do the same thing.