Table 3 Lung attenuation gradients when the lung field was divided into two parts on computed tomography in the standing and supine positions (100 participants).

Supine

Anteroposterior direction

Level of the aortic arch

Right upper lobe

0.38 ± 0.37

0.83 ± 0.58

0.44 (0.31–0.68)

< 0.0001

Left upper lobe

0.34 ± 0.42

0.75 ± 0.55

042 (0.28–0.56)

< 0.0001

Level of the inferior pulmonary vein

Right middle lobe

0.01 ± 0.84

0.53 ± 1.18

0.58 (0.17–1.00)

0.0045

Right lower lobe

0.30 ± 0.59

1.19 ± 0.97

1.01 (0.14–1.28)

< 0.0001

Left upper lobe

0.32 ± 0.79

0.44 ± 1.14

0.09 (-0.17–0.36)

0.4745

Left lower lobe

0.30 ± 0.89

1.40 ± 1.24

1.14 (0.83–1.45)

< 0.0001

Level just above the diaphragm

Right lower lobe

0.45 ± 0.59

0.58 ± 0.80

0.16 (-0.05–0.38)

0.1358

Left lower lobe

0.64 ± 0.76

0.57 ± 0.72

-0.08 (-0.26–0.09)

0.3333

Craniocaudal direction

Right lower lobe

-0.15 ± 0.29

0.20 ± 0.35

0.35 (0.25–0.44)

< 0.0001

Left lower lobe

-0.02 ± 0.31

0.05 ± 0.51

0.05 (-0.05–0.15)

0.3498

Standing

Anteroposterior direction

Level of the aortic arch

Right upper lobe

-0.05 ± 0.38

-0.05 ± 0.37

-0.003 (-0.11–0.10)

0.9496

Left upper lobe

-0.05 ± 0.39

-0.05 ± 0.61

-0.04 (-0.16–0.09)

0.5517

Level of the inferior pulmonary vein

Right middle lobe

-0.61 ± 1.27

-0.33 ± 1.27

0.28 (-0.13–0.70)

0.1849

Right lower lobe

-0.34 ± 0.64

0.01 ± 0.55

0.36 (0.18–0.86)

< 0.0001

Left upper lobe

-0.36 ± 1.16

-0.58 ± 0.89

-0.26 (-0.57–0.54)

0.1044

Left lower lobe

-0.12 ± 0.79

0.08 ± 0.70

0.19 (-0.02–0.40)

0.0802

Level just above the diaphragm

Right lower lobe

-0.15 ± 0.62

-0.18 ± 0.42

-0.03 (-0.19–0.13)

0.7302

Left lower lobe

-0.25 ± 1.34

-0.14 ± 0.52

-0.04 (-0.16–0.87)

0.4343

Craniocaudal direction

Right lower lobe

0.02 ± 0.23

0.64 ± 0.45

0.62 (0.54–0.70)

0.0001

Left lower lobe

0.08 ± 0.26

0.71 ± 0.48

0.64 (0.56–0.72)

< 0.0001