Time to Exhale: Additional Value of Expiratory Chest CT in Chronic Obstructive Pulmonary Disease

Table 4

Comparison between inspiratory and expiratory correlation coefficients.

Quantified CT parameter	Lung function parameter	Correlation inspiration	Correlation expiration	value	value
Volume	VC	0.0577	−0.2367	3.1409	0.0017
Volume	FEV1	−0.1314	−0.4643	3.631	0.0003
Volume	FEV1%VC	−0.3605	−0.5225	1.8699	0.0615
Volume	RV	0.3587	0.6466	−3.3049	0.001
Volume	TLC	0.3809	0.5503	−1.9779	0.0479
Volume	RV%TLC	0.1813	0.549	−4.0252	0.0001
Volume	sRtot	0.102	0.4345	−3.6152	0.0003
MLD	VC	−0.0194	0.1563	−1.9585	0.0502
MLD	FEV1	0.2186	0.4696	−2.9337	0.0033
MLD	FEV1%VC	0.4856	0.6376	−2.005	0.045
MLD	RV	−0.4421	−0.6362	2.4796	0.0132
MLD	TLC	−0.5098	−0.6378	1.7201	0.0854
MLD	RV%TLC	−0.2924	−0.6108	3.7492	0.0002
MLD	sRtot	−0.3061	−0.5225	2.5933	0.0095
FWHM	VC	0.0602	0.2715	−1.8312	0.0671
FWHM	FEV1	0.0918	0.4228	−2.9634	0.003
FWHM	FEV1%VC	0.1818	0.403	−1.9774	0.048
FWHM	RV	−0.1707	−0.416	2.1972	0.028
FWHM	TLC	−0.1718	−0.3402	1.4834	0.138
FWHM	RV%TLC	−0.0505	−0.4579	3.6813	0.0002
FWHM	sRtot	−0.0756	−0.3345	2.2735	0.023
LAV	VC	−0.2261	−0.346	3.1849	0.0014
LAV	FEV1	−0.3907	−0.4465	1.5801	0.1141
LAV	FEV1%VC	−0.4002	−0.336	−1.7761	0.0757
LAV	RV	0.5293	0.5748	−1.3982	0.1621
LAV	TLC	0.4354	0.405	0.8695	0.3846
LAV	RV%TLC	0.4527	0.5015	−1.4274	0.1535
LAV	sRtot	0.5235	0.5602	−1.1266	0.2599

MLD: mean lung density; FWHM: full width half max; LAV: low attenuation volume; VC: vital capacity; FEV₁: forced expiratory volume in one second; FEV₁%VC: Tiffeneau index; RV: residual volume; TLC: total lung capacity; sR_tot: specific total airway resistance.