Small pulmonary vascular alteration and acute exacerbations of COPD: quantitative computed tomography analysis

Figures & data

Figure 1 Measurement of cross-sectional area of small pulmonary vessels using ImageJ software in normal subjects.

Notes: (A) CT image of lung field segmented within the threshold values from −500 to −1,024 HU. (B) Binary image converted with window level of −720 HU from segmented image. (C) Pulmonary vessels are displayed in black.

Abbreviation: CT, computed tomography.

Table 1 Demographic characteristics, pulmonary function tests, and corresponding CT measurements in the COPD subjects

Characteristic	COPD subjects (n=153)
Age (years)	69.68±9.71
Sex, % female	39 (25.49%)
BMI (kg/m^2)	23±3.70
BSA (m^2)	1.70±0.20
FEV1/FVC	59.03±13.87
FEV1%	56.55±23.14
%CSA<5	0.56±0.19
%CSA5–10	0.20±0.08

Note: Data presented as mean ± SD or n (%).

Abbreviations: BMI, body mass index; BSA, body surface area; COPD, chronic obstructive pulmonary disease; %CSA_<5, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels less than 5 mm²; %CSA_5–10, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels between 5 and 10 mm²; CT, computed tomography; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity.

Table 2 ICC calculation for pulmonary vascular parameters between the two readers

Pulmonary vascular parameters	ICC	95% CI
%CSA<5	0.92	0.901–0.932
%CSA5–10	0.90	0.872–0.913

Notes: ICC >0.80 denotes excellent agreement, ICC >0.6 denotes substantial agreement, ICC >0.4 denotes moderate agreement, and ICC <0.4 denotes poor agreement.

Abbreviations: CI, confidence interval; %CSA_<5, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels less than 5 mm²; %CSA_5–10, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels between 5 and 10 mm²; ICC, intraclass correlation coefficient.

Table 3 The comparison in %CSA among patients by COPD severity

Parameters	Controls (n=154)	Mild (n=30)	Moderate (n=61)	Severe (n=62)
%CSA<5	0.82±0.15	0.75±0.15	0.63±0.15a,b	0.46±0.11a,b,c
%CSA5–10	0.33±0.16	0.18±0.06a	0.20±0.11a	0.19±0.08a

Notes: Data presented as mean ± SD.

a P<0.001, compared with control;

b P<0.001, compared with mild group;

c P<0.001, compared with moderate group.

Abbreviations: COPD, chronic obstructive pulmonary disease; %CSA_<5, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels less than 5 mm²; %CSA_5–10, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels between 5 and 10 mm².

Table 4 Comparison of demographic characteristics, PFTs, and corresponding CT measurements between the patients with and without AECOPD

Characteristic	AECOPD (n=79)	Non-AECOPD (n=74)	P-value
Age (years)	71.15±8.48	68.25±11.01	0.129
Sex, female	13 (16.46%)	26 (35.14%)	<0.001
BMI (kg/m^2)	23.00±3.40	23.00±4.10	0.234
BSA (m^2)	1.70±0.20	1.60±0.20	0.760
FEV1/FVC	57.42±13.82	63.57±13.82	0.052
FEV1%	53.92±23.18	64.61±25.23	<0.001
COPD severity
Mild COPD	11 (13.92%)	19 (25.68%)	0.144
Moderate COPD	25 (31.65%)	36 (48.65%)	0.159
Severe COPD	43 (54.43%)	19 (25.68%)	<0.001
%CSA<5	0.41±0.13	0.68±0.18	<0.001
%CSA5–10	0.20±0.07	0.20±0.10	0.109

Note: Data presented as mean ± SD or n (%).

Abbreviations: AECOPD, acute exacerbation of COPD; BMI, body mass index; BSA, body surface area; COPD, chronic obstructive pulmonary disease; %CSA_<5, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels less than 5 mm²; %CSA_5–10, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels between 5 and 10 mm²; CT, computed tomography; FEV₁, forced expiratory volume in 1 second; FVC, forced vital capacity; PFT, pulmonary function test.

Figure 2 ROC analyses of parameters for the prediction of AECOPD. Note: AUC was highest for %CSA_<5 (AUC =0.764, 95% CI =0.677–0.851).

Abbreviations: AUC, area under the curve; AECOPD, acute exacerbations of chronic obstructive pulmonary disease; CI, confidence interval; %CSA_<5, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels less than 5 mm²; %CSA_5–10, percentage of total lung area taken up by the cross-sectional area of pulmonary vessels between 5 and 10 mm²; ROC, receiver operating characteristic.