A new study is showcasing how much more information MRI and CT can provide on the symptoms and physical capabilities of those with chronic obstructive pulmonary disease (COPD) over and beyond the typical lung function test.

Specifically, in patients with mild-to-moderate COPD, MRI measurements of emphysema were correlated with exercise limitations, while both CT and MRI measurements shed light that explained other symptoms in those with only mild COPD, according to the findings published online this week in Radiology.

COPD diagnosis typically involves a spirometry lung function test that has patients breathe forcefully into a tube to measure forced expiratory volume in one second (FEV1). However, FEV1 doesn’t tell the whole story, said study co-author Grace Parraga, PhD, from the Robarts Research Institute in London, Ontario, Canada.

“COPD is a very heterogeneous disease,” said Parraga in a statement. “Patients are classified based on spirometry, but patients with the same air flow may have different symptoms and significant variation in how much regular activity they can perform, such as walking to their car or up the stairs in their home.”

Parraga and colleagues wanted to assess how much additional information on COPD symptoms could be gleaned from imaging, particularly in those with mild-to-moderate disease, so they performed a study featuring 116 people with COPD, 80 of whom had a milder variety of the disease. Patients all underwent lung capacity testing, filled out a quality of life questionnaire and performed a six-minute walking test. They also underwent conventional CT and an inhaled hyperpolarized helium 3 MRI scan.

Results showed that in patients with more severe COPD, FEV1 was the only significant contributor in a multivariate model for the six-minute walking test. However, in the 80 patients with mild-to-moderate COPD, FEV1 was not a significant variable. Instead, MRI measurements of emphysema played a dominant role in explaining exercise limitation, while both MRI and CT measurements were correlated with the presence of COPD symptoms such as cough, breathlessness and sputum production.

“There are numerous, interrelated factors that contribute to symptoms and exercise limitation in COPD that are often difficult to understand and appreciate, especially in patients with ‘mild’ disease in whom FEV1 may not be very enlightening,” wrote the authors.

Parraga added that emphysema is under-recognized as a source of COPD, and while there is no cure, there are ways to mitigate symptoms. “With lung imaging, we can look at patients with mild disease much more carefully and change treatment if necessary,” she said.