Computed tomography total vessel count and vessel count percentages: associations with exercise capacity, symptoms and rapid FEV1 decline in COPD.

BACKGROUND

Existing computed tomography (CT) vascular pruning measures rely on volumes, such as the proportion of blood volume in vessels with cross-sectional area (CSA) ≤5 mm2 or CSA ≤10 mm2/total blood vessel volume (BV5/TBV or BV10/TBV, respectively), but may underestimate vascular pruning due to blood redistribution to larger vessels in individuals with milder COPD. We aim to develop a novel CT vessel measure, the total vessel count (TVC), quantify small and combined small/intermediate vessel count percentages, and compare these measures with BV5/TBV and BV10/TBV in terms of associations with lung function and its decline. As a secondary aim, associations with exercise capacity and COPD symptoms will be investigated.

METHODS

CanCOLD (Canadian Cohort Obstructive Lung Disease) participants underwent CT imaging. BV5/TBV and BV10/TBV were generated using vessel segmentation. TVC and small (CSA ≤5 mm2, VC≤5/TVC) and combined small/intermediate (CSA ≤10 mm2, VC≤10/TVC) vessel count percentages were calculated. Fully adjusted regression models assessed associations with forced expiratory volume in 1 s (FEV1), FEV1/forced vital capacity (FVC), diffusing capacity of the lung for carbon monoxide (D LCO), accelerated FEV1 decline over 3 years, peak oxygen uptake (V̇ O2 peak), 6-min walk distance (6MWD) and Medical Research Council (MRC) dyspnoea scale.

RESULTS

1254 CanCOLD participants were investigated. TVC, VC≤5/TVC and VC≤10/TVC were associated with FEV1/FVC (p<0.05), D LCO (p<0.05) and FEV1 decline (p<0.05); VC≤10/TVC was associated with V̇ O2 peak (p<0.05), and both VC≤5/TVC and VC≤10/TVC were associated with MRC (p<0.05). BV5/TBV and BV10/TBV were only associated with 6MWD (p<0.05) and MRC (p<0.05).

CONCLUSION

Pulmonary vessel count percent, a measure of vasculature narrowing/loss, is associated with lung function and its decline, reduced exercise capacity, and increased symptoms in COPD.