Imaging Explains COPD Symptoms, Exercise Limitations

Magnetic resonance imaging can help measure exercise limitations in patients with mild-to-moderate chronic obstructive pulmonary disease (COPD), and both MRI and CT can provide information about their symptoms, according to a study published in Radiology.

Canadian researchers sought to determine the role of imaging measurements of emphysema and airway disease in determining COPD symptoms and exercise limitation, particularly in patients with mild-to-moderate disease.

A total of 116 patients Global Initiative for Chronic Obstructive Lung Disease (GOLD) grade U (unclassified) or grade I–IV COPD, between 50 and 85 years, participated in the trial. The patients had a smoking history of 10 or more pack-years. The patients underwent conventional CT, inhaled noble gas MRI, and lung capacity testing. The subjects also completed a quality of life questionnaire and took a six-minute walk (6MWD) to measure exercise tolerance.[[{"type":"media","view_mode":"media_crop","fid":"39178","attributes":{"alt":"","class":"media-image media-image-right","id":"media_crop_2579158523409","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"3936","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","style":"height: 175px; width: 175px; border-width: 0px; border-style: solid; margin: 1px; float: right;","title":"Grace Parraga, PhD","typeof":"foaf:Image"}}]]

The results showed that multivariate modeling for the 6MWD for 80 patients with GOLD grade U–II COPD, apparent diffusion coefficient (ADC), diffusing capacity of the lung for carbon monoxide and residual volume/total lung capacity were significant variables, while forced expiratory volume in 1 second (FEV1) and airway disease measurements were not. In 36 patients with GOLD grade III or IV disease, FEV1 was the only significant contributor in a multivariate model for 6MWD. MR imaging emphysema measurements also made the greatest relative contribution to symptoms in patients with milder (GOLD grade U–II) COPD and in grade III or IV disease.

 “FEV1 doesn’t tell the whole story,” study co-author Grace Parraga, PhD, of the Robarts Research Institute in London, Ontario, said in a release. “With lung imaging, we can look at patients with mild disease much more carefully and change treatment if necessary.”

“One in four hospital beds in Canada is occupied by a COPD patient, and many of them return to a hospital because they’re not being optimally treated,” Parraga said. “Our study shows that when COPD symptoms and exercise limitations are discordant with FEV1 measurements, we should consider using lung imaging to provide a deeper understanding of the patient’s disease and to help improve their quality of life.”

Further imaging studies related to respiratory disease are planned.