Computed tomography measurement of pulmonary artery for diagnosis of COPD and its comorbidity pulmonary hypertension

Figures & data

Figure 1 Measurement of main pulmonary artery (MPA), right pulmonary artery (RPA), ascending aorta (AAo), and descending aorta (DAo) diameters at the level of the pulmonary artery bifurcation.

Note: MPA diameter =31.6 mm, RPA diameter =26.6 mm, AAo diameter =32.7 mm, and DAo diameter =26.6 mm.

Figure 2 Measurement of left pulmonary artery (LPA) diameter at the widest part after main pulmonary artery bifurcation.

Note: LPA diameter =22.6 mm.

Figure 3 Receiver operating characteristic (ROC) curves showing the diagnostic accuracy of different CT measurements for COPD.

Notes: MPA was selected as the best index for the diagnosis of COPD. The optimal threshold value was 27.5 mm (area under the curve =0.711, specificity 54%, and sensitivity 80%).
Abbreviations: CT, computed tomography; COPD, chronic obstructive pulmonary disease; MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta.

Table 1 Demographics, blood, and CT comparisons for COPD

Variable	COPD	Number	Control	Number	P-value
Age (years)	69±10	221	62±11	115	P<0.001
Male, n (%)		175 (79.2%)		89 (77.4%)	0.70
CRP (mg/L)*	33.2±3.7	212	16.6±6.4	23	0.14
Blood sugar (mmol/L)*	5.72±0.14	213	6.10±0.35	76	0.23
TG (mmol/L)*	1.11±0.04	215	1.61±0.10	76	P<0.001
MPA diameter (mm)	28.7±5.2	221	25.3±3.4	115	P<0.001
RPA diameter (mm)	22.5±3.7	221	19.9±2.6	115	P<0.001
LPA diameter (mm)	20.9±3.1	206	18.8±2.5	115	P<0.001
AAo diameter (mm)	34.8±4.1	221	34.6±4.6	115	0.61
DAo diameter (mm)	25.1±2.8	207	25.7±3.4	115	0.14
MPA/AAo	0.83±0.15	221	0.74±0.11	115	P<0.001
MPA/DAo	1.15±0.23	207	0.99±0.14	115	P<0.001

Note:

* M ± SE; others, M ± SD.

Abbreviations: CT, computed tomography; COPD, chronic obstructive pulmonary disease; CRP, C-reactive protein; TG, triglyceride; MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta; M, mean; SE, standard error; SD, standard deviation.

Table 2 Area under the curve

Test result variable(s)	Area	Standard errora	Asymptotic sigb	Asymptotic 95% confidence interval
				Lower bound	Upper bound
MPA diameter	0.711	0.029	0.000	0.654	0.768
RPA diameter	0.705	0.029	0.000	0.649	0.762
LPA diameter	0.713	0.029	0.000	0.655	0.770
MPA/AAo	0.694	0.030	0.000	0.635	0.753
MPA/DAo	0.712	0.029	0.000	0.656	0.768

Notes: The test result variable(s), MPA diameter, RPA diameter, LPA diameter, and MPA/DAo, have at least one tie between the positive actual state and the negative actual state groups. Statistics may be biased.

a Under the nonparametric assumption.

b Null hypothesis: true area =0.5.

Abbreviations: MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta; sig, significance.

Table 3 Demographics, blood, and CT comparisons for COPD patients with or without PH

Variable	COPD-PH	Number	Non-PH	Number	P-value
Age (years)	71±10	56	69±10	165	0.23
Women, n (%)		12 (21.4%)		34 (20.6%)	0.90
CRP (mg/L)*	26.2±4.7	54	35.6±4.6	158	0.16
Blood sugar (mmol/L)*	6.22±0.41	54	5.55±0.12	159	0.13
TG (mmol/L)*	0.99±0.07	55	1.15±0.05	160	0.08
MPA diameter (mm)	32.1±6.2	56	27.5±4.3	165	P<0.001
RPA diameter (mm)	24.9±3.7	56	21.6±3.4	165	P<0.001
LPA diameter (mm)	22.4±3.4	55	20.3±2.7	151	P<0.001
AAo diameter (mm)	35.9±4.0	55	34.4±4.1	165	0.03
DAo diameter (mm)	25.1±3.1	55	25.1±2.7	152	0.97
MPA/AAo	0.90±0.19	56	0.81±0.13	165	P=0.001
MPA/DAo	1.30±0.32	55	1.09±0.17	152	P<0.001

Note:

* M ± SE; others, M ± SD.

Abbreviations: CT, computed tomography; COPD, chronic obstructive pulmonary disease; PH, pulmonary hypertension; CRP, C-reactive protein; TG, triglyceride; MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta; M, mean; SE, standard error; SD, standard deviation.

Table 4 Area under the curve for PH

Test result variable(s)	Area	Standard errora	Asymptotic sigb	Asymptotic 95% confidence interval
				Lower bound	Upper bound
MPA diameter	0.739	0.040	0.000	0.661	0.817
RPA diameter	0.753	0.037	0.000	0.681	0.825
LPA diameter	0.701	0.042	0.000	0.618	0.784
MPA/AAo	0.641	0.046	0.002	0.551	0.731
MPA/DAo	0.696	0.045	0.000	0.608	0.784

Notes: The test result variable(s), MPA diameter, RPA diameter, LPA diameter, and MPA/AAo, have at least one tie between the positive actual state and the negative actual state groups. Statistics may be biased.

a Under the nonparametric assumption.

b Null hypothesis: true area =0.5.

Abbreviations: PH, pulmonary hypertension; MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta.

Figure 4 Receiver operating characteristic (ROC) curves showing the diagnostic accuracy of different CT measurements for COPD-PH.

Notes: RPA was selected as the best index for the diagnosis of COPD-PH. The optimal threshold value was 23.4 mm (area under the curve =0.806, specificity 67%, and sensitivity 76%).
Abbreviations: CT, computed tomography; COPD, chronic obstructive pulmonary disease; PH, pulmonary hypertension; MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta.

Table 5 CT measured indexes and sPAP in linear regression analysis

Index	r	r^2	Sig (P-value)
MPA	0.508	0.258	P<0.001
RPA	0.405	0.164	P=0.001
LPA	0.271	0.073	P=0.023
MPA/AAo	0.544	0.296	P<0.001
MPA/DAo	0.594	0.353	P<0.001

Abbreviations: CT, computed tomography; sPAP, systolic pulmonary artery pressure; MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta; Sig, significance.

Figure 5 Comparison of MPA, RPA and LPA diameters, and MPA/AAo and MPA/DAo between COPD (non-PH) and COPD-PH.

Notes: All these indexes increased significantly in COPD-PH. represents the value beyond the 95% confidence interval. *represents the extreme value.
Abbreviations: COPD, chronic obstructive pulmonary disease; PH, pulmonary hypertension; MPA, main pulmonary artery; RPA, right pulmonary artery; LPA, left pulmonary artery; AAo, ascending aorta; DAo, descending aorta.