Quantitative CT measurements of small pulmonary vessels in chronic obstructive pulmonary disease: do they change on follow‐up scans?

Abstract

The aims of this study were to perform a longitudinal evaluation of the cross-sectional area (CSA) of small pulmonary vessels and the extent of emphysema measured on computed tomography (CT) scans of patients with chronic obstructive pulmonary disease (COPD), and to correlate the pulmonary vascular measurements with extent of emphysema. The institutional review board approved this retrospective study and waived the need for patients' informed consent. Seventy-four patients with COPD who underwent both initial and follow-up CT scans at an interval of ≥12 months were analysed. The CSA of small pulmonary vessels <5 mm(2) was measured, and the percentage of total CSA of the area of the lung (%CSA<5 ) was calculated. The extent of emphysema was assessed as the percentage of low attenuation area (%LAA, <-950 Hounsfield units). Comparisons between initial and follow-up measurements were performed using the Wilcoxon signed-rank test. The relationship between longitudinal changes in %CSA<5 and %LAA during the follow-up period was assessed using the Spearman rank correlation. The %LAA increased significantly on follow-up CT scans (P<0·0001). The %CSA<5 was slightly decreased on follow-up scans, but the difference was not significant. Although longitudinal change in %LAA was positively correlated with duration of follow-up period (ρ = 0·505, P<0·0001), longitudinal change in %CSA<5 was not. In conclusion, there was a progressive increase in the extent of emphysema over time, but no significant decrease in the CSA of small pulmonary vessels over the same time period.

Longitudinal changes in structural abnormalities using MDCT in COPD: do the CT measurements of airway wall thickness and small pulmonary vessels change in parallel with emphysematous progression?

“… 18 , 33 Saruya et al reported that there was a progressive increase in the extent of emphysema over time, but no significant decrease in small pulmonary vessels over the same time period. 20 They described that a decrease in the %CSA <5 may be associated with various improvements in the condition of the patients, such as smoking cessation, exacerbation risk, and pharmacotherapies, in comparison with emphysematous progression. Very recently, the morphological changes in small pulmonary vessels were reported to be associated independently with severe acute exacerbations.…”

“…Studies on emphysema progression have been addressed, 16 – 18 but studies about the changes in airway disease 19 or vascular remodeling are rare. 20 The association between alveolar destruction, airway disease, and pulmonary vascular change also remains unknown. Moreover, the data on structural changes after exacerbation or smoking cessation in COPD patients are not established.…”

COPD beyond proximal bronchial obstruction: phenotyping and related tools at the bedside

“…This decreased proportion of small pulmonary vessels has also been linked with pulmonary hypertension [116] and clinical outcomes [137] in COPD patients. Interestingly, longitudinal follow-up of CSA <5 mm 2 may indicate once more that vessel pruning precedes emphysema evolution [138]. Traditional explanations for pulmonary hypertension in COPD are emphysema destruction leading to loss of vasculature and hypoxemia-induced vasoconstriction.…”

Quantitative CT parameters correlate with lung function in chronic obstructive pulmonary disease: a systematic review and meta-analysis

“…The common threshold defining the lung parenchyma in emphysema was -900 to -960HU, and the most commonly used threshold was -950 HU [24]. In some study, different thresholds in the same sample had different correlations with airflow obstruction parameters in PFT [18,20,35,40].The broad range of published CCs between CT and PFT parameters were as follow: %LAA-950 and FEV 1 %pred, -0.66 to -0.09 [18,19]; %LAA-950 and FEV 1 /FVC, -0.75 to -0.09 [18,69]; %LAA 950 and FEV 1 %pred, -0.63 to -0.28 [19,59]; %LAA 950 and FEV 1 /FVC -0.66 to -0.54 [19,35];WA% and FEV 1 %pred, -0.713 to -0.044 [30,70];MLD and FEV 1 %pred, 0.18 to 0.85 [18,68]; MLD and FEV 1 /FVC, 0.21 to 0.89 [18,19];ATI and FEV 1 %pred, -0.725 to -0.29 [41,48]; WT and FEV 1 %pred, -0.68 to -0.13 [33,35]; WT and FEV 1 /FVC, -0.62 to -0.05 [33,35]; AI and FEV 1 %pred, 0.73 to 0.14 [28,33]; AI and FEV 1 /FVC, 0.32 to 0.07 [33,46];%LAA-950 and FEV 1 %pred by GE, -0.67 to -0.43 [26,60]; %LAA-950 and FEV 1 %pred by non-GE (such as Siemens, Toshiba, and Philips), -0.67 to -0.43 [39,47](Supplementary Table 3).…”