Vascular Proximity Coverage: A Novel CT-Based Marker of Pulmonary Vascular Distance to the Lung Parenchyma
Listed in
This article is not in any list yet, why not save it to one of your lists.Abstract
Rationale
Conventional CT-derived pulmonary vascular metrics quantify vascular pruning but do not assess spatial heterogeneity of vascular architecture. In COPD, peripheral microvascular pruning coexists with compensatory central vessel dilation, paradoxically preserving total vessel volume while reducing effective vascular penetration into lung parenchyma.
Objectives
To develop and validate Vascular Proximity Coverage (VPC), a novel distance-based CT biomarker quantifying spatial efficiency of pulmonary vascular distribution.
Methods
This retrospective analysis included 7,881 COPDGene participants with complete vascular segmentations. VPC is estimated by integrating the area under the cumulative lung tissue coverage curve at distances 0–10 mm from segmented vessel voxels. Multivariable models were used to assess associations with lung function, six-minute walk distance (6MWD), St. George’s Respiratory Questionnaire (SGRQ), mMRC dyspnea score and all-cause mortality adjusting for demographics, smoking, emphysema, scanner type, and BV5. We stratified the cohort into four groups defined by the median values of BV5 and VPC, yielding discordant (high-BV5/low-VPC, low-BV5/high-VPC) and concordant (high/high, low/low) vascular phenotypes.
Results
VPC declined across disease severity (5.82 ± 0.50 in non-smokers to 5.21 ± 0.64 in GOLD 4; p<0.001). Among spirometrically normal smokers, current smokers showed reduced VPC versus former smokers (5.31 vs. 5.68; p<0.001). Each standard deviation (SD) decrease in VPC was independently associated with reduced 6MWD (β=-16.8 m, 95% CI: -19.5 to -14.0), worse SGRQ (β=1.9, 95% CI: 1.4 to 2.4), and increased dyspnea (RR=1.05, 95% CI: 1.03–1.08; all p<0.001). The lowest VPC quartile, as compared to the reference quartile, was associated with 38% higher mortality (HR=1.38, 95% CI: 1.18–1.62; p<0.001). Based on median thresholds, high-BV5/low-VPC phenotype, compared to High-BV5/High-VPC, showed 24% increased mortality (HR=1.24, 95% CI: 1.08–1.42; p=0.002) despite preserved vessel volume.
Conclusions
VPC captures spatial heterogeneity of vascular architecture independent of vessel volume and detects subclinical vascular dysfunction in smokers without airflow obstruction.
AT A GLANCE COMMENTARY
Scientific Knowledge on the Subject
Current CT-based pulmonary vascular metrics, including volume of blood vessels less than 5 mm² cross-sectional area (BV 5 ) and total vessel volume, quantify the amount of visible vasculature but do not assess how effectively vessels reach the lung parenchyma for efficient gas exchange. In COPD, peripheral microvascular pruning commonly coexists with compensatory central vessel dilation, leading to preserved or increased total vascular volume despite compromised functional vascular distribution.
What This Study Adds to the Field
Vascular Proximity Coverage (VPC) is a novel distance-based CT biomarker that quantifies the spatial efficiency of pulmonary vascular distribution by measuring cumulative lung tissue coverage across distances from vessel walls. In 7,881 COPDGene participants, including non-smokers and PRISm subjects, lower VPC was independently associated with decreased lung function, reduced exercise capacity, worsened quality of life, and increased all-cause mortality over a median 10.8-year follow-up after adjusting for BV 5 and emphysema. VPC identified a high-risk phenotype with preserved vessel volume but impaired distribution (high-BV5/low-VPC) that carried 24% increased mortality risk and detected subclinical vascular dysfunction in smokers with normal spirometry.
