Table 4. Correlation analysis of pulmonary function tests (PFTs) with visual scores (VSs) and selected percentiles obtained from multidetector computed tomography (MDCT) attenuation histogram.

VSs, PERC	VC [%]	p value	DLCO [%]	p value
OE [%]	-0.57	<0.001	-0.49	0.004
GGO [%]	-0.45	0.004	-0.36	0.038
RET [%]	-0.31	0.053	-0.23	0.207
HC [%]	-0.05	0.754	-0.56	0.001
40th percentile [HU]	-0.51	0.001	-0.50	0.003
80th percentile [HU]	-0.56	<0.001	-0.62	<0.001
Δ VSs, Δ PERC	Δ VC [%/y]	p value	Δ DLCO [%/y]	p value
Δ OE [%/y]	-0.63	<0.001	-0.16	0.395
Δ GGO [%/y]	-0.36	0.031	-0.04	0.839
Δ RET [%/y]	-0.43	0.005	-0.25	0.189
Δ HC [%/y]	-0.23	0.156	+0.05	0.783
Δ 40th percentile [HU/y]	-0.58	<0.001	-0.48	0.008
Δ 80th percentile [HU/y]	-0.57	<0.001	-0.40	0.028

Summary of correlation analysis between pulmonary function tests (PFTs), visual scores (VSs), and selected percentiles (PERC) obtained from multidetector computed tomography (MDCT) attenuation histogram at initial MDCT and at 1-year follow-up. Pearson r coefficients were calculated for overall extent of abnormalities (OE), ground-glass opacities extent (GGO), reticulations extent (RET), honeycombing extent (HC) [all expressed as percentage of parenchyma involved (%)], and the density, expressed as Hounsfield Unit (HU), of selected percentiles obtained from the MDCT attenuation histogram with the percent predicted (%) of vital capacity (VC) and of diffusing capacity of the lung for carbon monoxide (DLCO) at baseline. The same coefficients were obtained for both longitudinal changes at 1-year (Δ) in VSs, expressed as percent per year (%/y), and in the density, expressed as Hounsfield Unit per year (HU/y), of selected percentiles obtained from the MDCT attenuation histogram with the variation, expressed as percent predicted per year (%/y), of VC% and of DLCO%. In bold p values statistically significant (p<0.05).