Lung Vessel Morphology Changes With Airway Obstruction

Introduction: Morphologic changes in the COPD lung also affect the lung vasculature. Most insights stem from pathologic examinations of end-stage disease and there is only limited data for milder COPD. Aims: To analyse the lung vasculature from thoracic CT images in a large cohort of patients with different grades of chronic airway obstruction from GOLD 0 (only symptoms) to GOLD 1&2 (FEV1≥50%) and GOLD 3&4 (<50%). Methods: The COSYCONET study acquired CT images in inspiration and expiration. An algorithm identified the lung vessels with diameters of 2-10mm and labelled them as arteries and veins. All segmentations were inspected by a radiologist to exclude failed results. Morphologic readouts were analysed with respect to GOLD stage. Results: Normalized inspiratory vessel volume decreased with disease severity (p<0.001) from median 3.05% of total lung volume in GOLD 0 (n=48) to 2.64% in GOLD 1&2 (n=250) to 2.57% in GOLD 3&4 (n=170). In expiration, normalized vessel volume decreased with GOLD stage (p<0.001) from 3.66% to 3.45% and 3.10%, respectively. This was mainly due to an increase in total lung volume with GOLD stage (p<0.001). However, total inspiratory vessel volume also increased (p<0.001) from 151mL to 173mL and 168mL and expiratory volume (p<0.001) from 120mL to 150mL and 155mL by GOLD grade. With severity of obstruction, vessels became straighter. This effect was stronger in expiration (p<0.001) than in inspiration (p=0.018). Changes in vessel volume and tortuosity were similar for men and women and were more pronounced in arteries than veins. Conclusion: Vessel morphology changes with severity of chronic airway obstruction and may reflect interactions between lung volume, loss of elasticity, and intrathoracic pressure.