University of Virginia Health System

RESEARCHERS AT U.VA. HEALTH SYSTEM VIEW LUNGS OF ASTHMATICS USING HYPERPOLARIZED GAS

The images we obtain from hyperpolarized helium-3 MR imaging are very clear. We can see how air flows through the lungs and easily find ventilation defects. This has been impossible with conventional techniques, as the lungs are very hard to see, said James R. Brookeman, professor of radiology and biomedical engineering and director of magnetic resonance research at U.Va. While additional studies are needed before hyperpolarized helium-3 MR imaging can be used in clinical practice, these studies are very encouraging. We are also studying this technique for detecting abnormalities in other areas of the body, like the colon and female reproductive organs.

The term hyperpolarized means that the magnetic nuclei of the gas atoms have been made to align predominately in the same direction. Physicists at Princeton University discovered that aligned atoms of helium-3, a benign gas, produce a magnetic resonance (MR) imaging signal that is much stronger than that observed with hydrogen-1 MR imaging, the conventional technique. Their collaboration with researchers at U.Va. led to these and other studies using the gas.

In the study, patients inhaled hyperpolarized helium-3, then held their breath for approximately ten seconds during the MR imaging. The images obtained were viewed and manipulated on a computer screen.

Ten asthmatics and five healthy volunteers were imaged. Three of those with asthma were evaluated a second time 20 minutes after using an inhaled bronchodilator. Researchers hoped to confirm the presence of lung ventilation defects in asthmatics and determine whether the defects are reversible with medication.

Seven of ten participants with asthma imaged had ventilation defects. At the time of the imaging, two were mildly symptomatic, while the remaining eight were asymptomatic. Researchers observed that the symptomatic patients had more numerous and larger ventilation defects. In the three asthmatics imaged again after using the inhaled bronchodilator, the defects resolved completely in one and decreased significantly in size in the other two. Because ventilation defects were found in even those without symptoms of asthma, and most defects were reversible, researchers concluded that hyperpolarized helium-3 MR imaging may be a viable method for assessing the presence of asthma as well as the response to therapy.

On Wednesday, researchers from U.Va. will present another study that evaluated hyperpolarized helium-3 MR imaging as a measure of lung function for patients with chronic obstructive pulmonary disease (COPD).

In both studies, helium-3 was polarized using a prototype commercial system manufactured by Nycomed Amersham Imaging of Princeton, N.J.

To view examples of images obtained using hyperpolarized helium-3 MR imaging or learn more about the University of Virginia Medical Imaging Program, visit the Web site at http://imaging.med.virginia.edu/hyperpolarized/index.htm.

November 30, 1999