Low-dose CT for quantitative analysis in acute respiratory distress syndrome

Table 1 Comparison between quantitative computed tomography results obtained at 60 and 140 tube current-exposure time product^a

60 mAs to 140 mAs		Mean ± SD₆₀	Mean ± SD₁₄₀	P	r ²	Bias	LOA
Baseline ( n = 12)	Lung volume (ml)	2,782 ± 666	2,785 ± 671	0.88	0.99	1.7	-114.0 to 109.0
	Lung tissue mass (g)	679 ± 102	683 ± 101	0.12	1.00	-4.5	-13.2 to 4.2
	Hyperinflated tissue (%)	0.6 ± 1.1	0.5 ± 1.0	0.08	0.97	0.1	-0.4 to 0.5
	Normally aerated tissue (%)	86.6 ± 2.9	86.4 ± 3.2	0.52	0.95	0.2	-1.7 to 2.1
	Poorly aerated tissue (%)	11.5 ± 3.4	11.8 ± 3.7	0.21	0.95	-0.3	-2.0 to 1.3
	Nonaerated tissue (%)	1.4 ± 0.5	1.3 ± 0.7	0.07	0.98	0.1	-0.1 to 0.2
ARDS ( n = 28)	Lung volume (ml)	2,022 ± 338	2,023 ± 343	0.91	0.99	-0.7	-64.3 to 62.8
	Lung tissue mass (g)	1,500 ± 159	1,498 ± 151	0.73	0.98	1.8	-51.4 to 55.0
	Hyperinflated tissue (%)	0.0 ± 0.1	0.0 ± 0.1	0.52	0.95	0.0	-0.1 to 0.1
	Normally aerated tissue (%)	11.4 ± 11.1	11.4 ± 11.1	0.91	0.99	0.0	-2.4 to 2.4
	Poorly aerated tissue (%)	33.1 ± 15.6	33.2 ± 16.0	0.72	0.98	0.0	-4.5 to 4.4
	Nonaerated tissue (%)	55.4 ± 23.2	55.4 ± 23.5	0.99	0.99	0.0	-5.5 to 5.5

^aARDS = acute respiratory distress syndrome; mAs = tube current-exposure time product; lung volume = total lung volume; lung tissue mass = total mass of lung tissue; hyperinflated tissue = mass of hyperinflated tissue; normally aerated tissue = mass of normally aerated tissue; poorly aerated tissue = mass of poorly aerated tissue; nonaerated tissue = mass of nonaerated tissue; P = P-value of the comparison between values obtained at 60 and at 140 mAs by paired t-test or signed rank-sum test as appropriate; r² = coefficient of determination of linear regression between values obtained at 60 and 140 mAs; bias and LOA = bias and limits of agreement (bias ± 1.96 SD) of the Bland-Altman analysis.

ISSN: 1364-8535