Imaging in Chronic Obstructive Pulmonary Disease: Ready for Prime Time?

Abstract

Chronic obstructive pulmonary disease (COPD) is a major global health burden, affecting over 392 million individuals and causing approximately 3.3 million deaths annually. Although spirometry remains the cornerstone for diagnosing airflow limitation, it incompletely reflects the structural and biological heterogeneity of the disease, and many smokers with preserved spirometry exhibit substantial parenchymal and airway abnormalities. Advances in imaging-particularly quantitative computed tomography (QCT), magnetic resonance imaging (MRI), and positron emission tomography (PET)-enable comprehensive assessment of structural, functional, and inflammatory processes in COPD. QCT-derived emphysema metrics, including the 15th percentile lung density, mean lung density, and low attenuation area percentage, are reproducible, sensitive to progression, and widely used as outcome measures. Small airway disease can be characterized using parametric response mapping and complementary voxel-based indices that detect subclinical gas trapping and regional volume changes. The concept of mechanically affected lung highlights functionally impaired regions adjacent to emphysema that contribute to disease progression and mortality. Airway remodeling metrics, such as Pi10, PiSlope, tapering slope, and airway fractal dimension, further provide prognostic information. Mucus plug burden independently predicts mortality and represents a potential surrogate endpoint in therapeutic trials. Advanced MRI techniques and 18F-fluorodeoxyglucose PET offer radiation-free or inflammatory insights, respectively. Current evidence supports that imaging is ready to evolve from an adjunct to a core element of COPD research and care.