Potential Value of Expiratory CT in Quantitative Assessment of Pulmonary Vessels in COPD

Abstract

Objective: To investigate the associations between intrapulmonary vascular volume (IPVV) depicted on inspiratory and expiratory CT scans and disease severity in COPD patients, and to determine which CT parameters can be used to predict IPVV.Methods: We retrospectively collected 89 CT examinations acquired on COPD patients from an available database. All subjects underwent both inspiratory and expiratory CT scans. We quantified the IPVV, airway wall thickness (WT), the percentage of the airway wall area (WA%), and the extent of emphysema (LAA%−950) using an available pulmonary image analysis tool. The underlying relationship between IPVV and COPD severity, which was defined as mild COPD (GOLD stage I and II) and severe COPD (GOLD stage III and IV), was analyzed using the Student's t-test (or Mann-Whitney U-test). The correlations of IPVV with pulmonary function tests (PFTs), LAA%−950, and airway parameters for the third to sixth generation bronchus were analyzed using the Pearson or Spearman's rank correlation coefficients and multiple stepwise regression.Results: In the subgroup with only inspiratory examinations, the correlation coefficients between IPVV and PFT measures were −0.215 ~ −0.292 (p < 0.05), the correlation coefficients between IPVV and WT3−6 were 0.233 ~ 0.557 (p < 0.05), and the correlation coefficient between IPVV and LAA%−950 were 0.238 ~ 0.409 (p < 0.05). In the subgroup with only expiratory scan, the correlation coefficients between IPVV and PFT measures were −0.238 ~ −0.360 (p < 0.05), the correlation coefficients between IPVV and WT3−6 were 0.260 ~ 0.566 (p < 0.05), and the correlation coefficient between IPVV and LAA%−950 were 0.241 ~ 0.362 (p < 0.05). The multiple stepwise regression analyses demonstrated that WT were independently associated with IPVV (P < 0.05).Conclusion: The expiratory CT scans can provide a more accurate assessment of COPD than the inspiratory CT scans, and the airway wall thickness maybe an independent predictor of pulmonary vascular alteration in patients with COPD.

Contributions of Emphysema and Functional Small Airway Disease on Intrapulmonary Vascular Volume in COPD

“…The emphysema had a greater impact on expiratory IPVV, and IPVV difference and relative values. However, Cao found that compared with LAA-950, the airway wall thickness had a more significant effect on expiratory IPVV and IPVV difference and relative values, 24 suggesting further exploration of the pathophysiology of the effects of emphysema and small airway disease on pulmonary blood vessels.…”

“…Cao also found that expiratory IPVV increased with COPD severity, and the difference decreased from the inspiratory phase, which were consistent with the findings of this study. 24 …”

“…Cao also found that expiratory IPVV increased with COPD severity, and the difference decreased from the inspiratory phase, which were consistent with the findings of this study. 24 Previous studies have assessed the relationship between small pulmonary vessels, which measured using the proportion of vessels with a cross-sectional area of <5mm 2 (%CSA <5mm 2 or BV5). Most of the studies found that %CSA<5mm 2 or BV5 was positively correlated with FEV1 and FEV1/FVC, but negatively correlated with LAA %-950.…”

Prediction of disease severity in COPD: a deep learning approach for anomaly-based quantitative assessment of chest CT

“…Additionally, these methods rely on obtaining local and global labels, which can be difficult and subjective to acquire. Moreover, previous DL methods have primarily focused on utilizing a single CT image during full inspiration, neglecting the potential benefits of incorporating full expiration CT scans as surrogate markers for small-airway inflammation [ 11 , 12 ]. While large-scale cohort studies include expiratory CT scans for this purpose, their value for DL methods in COPD diagnosis has not yet been explored.…”