Imaging Markers of Chronic Obstructive Pulmonary Disease on Computed Tomography of the Lungs: a Narrative Review

Chronic obstructive pulmonary disease (COPD) is a heterogeneous disorder in which spirometry reflects airflow limitation but incompletely captures the underlying structural injury. Patients with similar spirometric impairment may have markedly different patterns of emphysema, small-airway disease, and pulmonary vascular involvement. Computed tomography (CT) can visualize these abnormalities in vivo and may detect structural changes before overt airflow limitation develops. This narrative review examined whether CT-derived imaging markers provide clinically meaningful information beyond spirometry, particularly for phenotyping, early structural detection, prognostic enrichment, and selective clinical decision support. A focused narrative review of diverse publications in PubMed, published between January 2000 and April 2025, was conducted using COPD-related MeSH terms and free-text keywords. Across the reviewed literature, emphysema, quantified by low-attenuation area and emphysema index, and air-trapping measures showed consistent associations with expiratory volume measures and identified structural abnormalities in symptomatic smokers with preserved spirometry. Airway wall metrics such as wall area percentage distinguished airway-predominant phenotypes and were associated with airflow limitation and chronic bronchitis. CT vascular markers, including small-vessel cross-sectional area and the pulmonary artery-to-aorta ratio, reflected microvascular disease; a pulmonary artery enlargement to aorta ratio greater than 1 independently predicted severe exacerbations. Xenon CT and dual-energy CT added regional ventilation and perfusion information but remain investigational. CT imaging markers add complementary structural, phenotypic, and prognostic information beyond spirometry for established COPD and pre-COPD. Their most supported current role is phenotypic characterization and prognostic enrichment in selected clinical settings, whereas advanced functional CT techniques remain research tools. Routine CT for all patients is not supported by current Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidance.