Identifying small airway disease in its earliest stages, when it is most treatable, could potentially lead to new drug therapies for those with COPD, according to University of Michigan researchers who have developed a new COPD imaging diagnostic.
Bronchioles, which are less than 2 mm in internal diameter, are too small to be visualized on CT imaging and are not well-reflected by pulmonary function tests, researchers say.
So scientists have developed a new technique called Parametric Response Mapping (PRM) to identify small airway abnormalities related to COPD. PRM is a noninvasive technique that measures lung density during inhalation and exhalation.
In a study published in the American Journal of Respiratory and Critical Care Medicine, the team examined lung tissue from patients with COPD undergoing lung transplantation as well as those with healthy donated tissue. Researchers then mapped those samples back to the CT scans taken before surgery. They confirmed that PRM was able to noninvasively identify small airway loss, narrowing, and obstruction.
“Now we have confidence in our ability to identify airway disease when imaging COPD patients,” said Senior author MeiLan Han, MD, a lung specialist and professor of internal medicine at the University of Michigan. “PRM is already clinically available and used by University of Michigan clinical teams to assess patients with COPD. This is what we mean by bench to bedside medicine.”
Han noted, however, “We still need to validate the type of airway disease the PRM technique identifies in patients with milder disease. That type of lung tissue is more difficult to obtain, but we are working on techniques that would allow us to use smaller amounts of lung tissue to make such studies feasible.”
By helping to identify patients at risk for disease progression, PRM can serve as a noninvasive measure to aid clinical trials of new therapeutics, the researchers concluded.
“These results illustrate the importance of developing noninvasive techniques for improving diagnostic capabilities and advancing new therapies needed to tackle this devastating disease,” said James Kiley, PhD, director of the Division of Lung Diseases at the National Heart, Lung, and Blood Institute. “The refinement of this and similar approaches could also advance the study of COPD at its earliest stages of development.”