The Salt Lake Tribune -- U. Physicist's Research on Gas Flow in Lungs Shows How They Function

U.Physicist's Research on Gas Flow in Lungs Shows How They Function

December 5, 2002
BY GREG LAVINE
THE SALT LAKE TRIBUNE

    Seeing how gases flow in and out of human lungs once stood as a nearly insurmountable challenge for doctors. Advances in physics now allow this feat using special magnetic resonance imaging machines.
    University of Utah physicist Brian Saam has been involved in research on hyperpolarized gases that have allowed intricate images of the lungs at work. Saam discussed his work during the College of Science's Science at Breakfast series Wednesday, saying researchers previously thought it would be "too hard" to use existing MRI devices to effectively scan the lungs.
    Traditionally, MRI involves water molecules found throughout the human body, though not in large quantities in the lung. A magnetic field generated in an MRI unit affects protons found in the nuclei of the hydrogen molecules that make up water. These protons act as tiny magnets, which spin either up or down.
    The magnetic field can change the direction some of the protons spin, information that eventually leads to images of areas inside the body.
    Saam has researched how to hyperpolarize helium 3. If this specially treated gas is present in the lungs, an MRI can produce an image. Certain MRI machines can now detect the movement for this version of helium in and out of the lungs.
    To prepare the helium, it is placed inside a glass container along with another element, rubidium. The glass unit is then heated in an oven. During the heating process, laser light bombards the mixture.
    The laser beams strike some of the rubidium atoms, which in turn bump into the helium. When these two substances collide, their spins are changed. The new spin for the affected helium protons can be picked up using MRI.
    Patients inhale the gases and are then placed inside an MRI unit. Images show how the gas is distributed. Bronchial tubes and other lung features become visible as the gas moves inside these parts.
    Saam said the MRI technique is still undergoing Food and Drug Administration trials. Researchers are trying to figure out how much helium 3 should be inhaled for the imaging.
    Emphysema and cystic fibrosis are among the diseases that could benefit from the technique if it receives FDA approval.
    "If you want to diagnose lung disease, you might want to take pictures of the gas moving in and out of the lungs," Saam said.
    Doctors can ask patients if they are breathing well, but an MRI of the lungs could actually show how well they are breathing.
    Duke University physicist G. Allan Johnson's lab performed the first imaging using hyperpolarized gases in 1994 using a guinea pig. Saam and several other scientists who were pushing to use the gases in medical imaging worked with Johnson on the early imaging.
    "It's more than promising," Johnson said of using hyperpolarized gases with MRI. "It's delivering on that promise."
    glavine@sltrib.com