MRI Technique to Visualise Lung's Response to Asthma-Testing Drug

A magnetic resonance imaging (MRI) technique developed by Duke University Medical Center researchers enables them to visualize the lungs of live laboratory rats as the animals receive a drug, called methacholine, used to test for asthma. The non-invasive imaging method enables scientist to observe as tiny airways in the lungs respond to the medication, providing the researchers with more detailed information about lung function than can traditional diagnostic methods.

The "magnetic resonance microscopy" technique enables scientists to zoom in on airways as small as 100 microns, about the size of a human hair. "We're visualizing the behavior of the smallest airways, a critical element in understanding such pulmonary diseases as asthma," said G. Allan Johnson, Ph.D., director of Duke's Center for In Vivo Microscopy.

The study results were prepared for presentation at American Thoracic Society meeting in Seattle on May 21, 2003. The research was sponsored by the NIH National Center.

"Methacholine challenge" tests are a standard means of diagnosing asthma. The drug causes the airways of lungs in both humans and rats to constrict. Asthmatic patients' lungs tend to overreact to the medication, an indication of the disease. Traditionally, a patient's response to the drug must be determined indirectly by measuring the amount of air exhaled.

"Using the traditional techniques, it's hard to pinpoint the site of constriction in the lungs to identify the triggers for an asthma attack," said Ben Chen, Ph.D., a research associate at the Duke center and lead investigator of the study. "The lung is a complex structure yet air only enters and exit through the mouth and nose making lung measurement difficult. This imaging technique opens up a whole new potential for measuring local lung function. With this method, we can see regional changes in flow and determine visually which part of the lung is impaired".

In combination with the latest molecular genetics techniques, the imaging method can aid in identifying the root causes of lung disease, Chen said. By homing in on the precise location of lung abnormalities, it might ultimately lead to more targeted treatment for asthma and other lung disorders, he added.

The researchers' basic discoveries made in animal models of disease can be applied toward understanding human disease, Johnson emphasized.

Source : Pharmabiz, May 29, 2003