Computed tomography total vessel count and vessel count percentages: associations with exercise capacity, symptoms
Gaurav Veer Singh1, Huma Asghar1, Sophie É Collins2
1Department of Physics, Toronto Metropolitan University, Toronto, ON, Canada.
Insights
A new CT scan measure, total vessel count (TVC), better reflects vascular pruning in chronic obstructive pulmonary disease (COPD) than existing methods. TVC is linked to lung function, exercise capacity, and COPD symptoms.
Area of Science:
- Pulmonary imaging and vascular analysis
- Chronic Obstructive Pulmonary Disease (COPD) research
- Cardiopulmonary function assessment
Background:
- Current CT-based vascular pruning metrics (e.g., BV5/TBV, BV10/TBV) may underestimate disease severity in COPD due to blood redistribution.
- A novel CT measure, total vessel count (TVC), is proposed to more accurately quantify vascular pruning.
Purpose of the Study:
- To develop and validate TVC and related vessel count percentages (VC≤5/TVC, VC≤10/TVC) as CT-based measures of pulmonary vasculature in COPD.
- To compare the associations of TVC-based measures with traditional volume-based measures (BV5/TBV, BV10/TBV) regarding lung function, its decline, exercise capacity, and COPD symptoms.
Main Methods:
- CT imaging data from 1254 CanCOLD participants were analyzed.
- Vessel segmentation was used to calculate BV5/TBV and BV10/TBV.
- TVC, VC≤5/TVC, and VC≤10/TVC were computed. Associations with FEV1, FEV1/FVC, DLCO, FEV1 decline, VO2peak, 6MWD, and MRC scores were assessed using regression models.
Main Results:
- TVC, VC≤5/TVC, and VC≤10/TVC showed significant associations with FEV1/FVC, DLCO, and FEV1 decline.
- VC≤10/TVC was associated with VO2peak, while both VC≤5/TVC and VC≤10/TVC correlated with MRC scores.
- BV5/TBV and BV10/TBV were primarily associated with 6MWD and MRC scores.
Conclusions:
- Pulmonary vessel count percentage, reflecting vasculature narrowing or loss, is significantly associated with impaired lung function and its progression in COPD.
- This novel CT measure is also linked to reduced exercise capacity and increased symptom burden in individuals with 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.
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