Table 3.
Intra-observer and inter-observer concordance in ATI measurements
| Position of the ROIa) (ROI size) | CCC (95% CI) | Pearson’s r | Mean difference, dB/cm/MHz (95% limits of agreement) | |
|---|---|---|---|---|
| Intra-observer concordance (best image, ROI at 2 cm below the liver capsule, ROI length: 3 cm) | ||||
| Intercostal | 0.92 (0.88 to 0.95) | 0.92 | 0.002 (-0.080 to 0.084) | |
| Subcostal | 0.80 (0.72 to 0.89) | 0.81 | -0.001 (-0.141 to 0.139) | |
| Left lobe (n=14) | 0.67 (0.43 to 0.90) | 0.70 | -0.001 (-0.181 to 0.183) | |
| Inter-observer concordance | ||||
| (a) Intercostal, 2 cm, best image (3 cm) | 0.89 (0.82 to 0.96) | 0.89 | 0.005 (-0.085 to 0.095) | |
| (b) Intercostal, 2 cm, 90° (3 cm) | 0.71 (0.53 to 0.89) | 0.72 | 0.001 (-0.142 to 0.145) | |
| (c) Intercostal, 2.5 cm (3 cm) | 0.78 (0.64 to 0.91) | 0.78 | -0.004 (-0.137 to 0.128) | |
| (d) Intercostal, 3.0 cm (3 cm) | 0.76 (0.62 to 0.91) | 0.76 | 0.003 (-0.126 to 0.131) | |
| (e) Intercostal, 2 cm, best image (5 cm) | 0.78 (0.63 to 0.93) | 0.78 | 0.004 (-0.112 to 0.120) | |
| (f) Subcostal, 2 cm, best image | 0.74 (0.57 to 0.90) | 0.76 | 0.001 (-0.174 to 0.176) | |
| (g) Left lobe, 2 cm, best image (n=14) | 0.58 (0.12 to 1.00) | 0.58 | -0.008 (-0.248 to 0.232) | |
| (h) Each measurement in a different locationb) | 0.69 (0.51 to 0.87) | 0.70 | 0.005 (-0.141 to 0.151) | |
| (i) Free breathing, intercostalb) | 0.69 (0.51 to 0.87) | 0.71 | 0.023 (-0.156 to 0.202) | |
| Concordance assessed using the values obtained with the (a) position as reference | ||||
| (b) Intercostal, 2 cm, 90° (3 cm) | 0.89 (0.84 to 0.94) | 0.90 | 0.004 (-0.077 to 0.086) | |
| (c) Intercostal, 2.5 cm (3 cm) | 0.82 (0.74 to 0.90) | 0.83 | -0.020 (-0.133 to 0.093) | |
| (d) Intercostal, 3.0 cm (3 cm) | 0.61 (0.48 to 0.74) | 0.70 | -0.052 (-0.199 to 0.096) | |
| (e) Intercostal, 2 cm, best image (5 cm) | 0.67 (0.54 to 0.80) | 0.74 | -0.038 (-0.160 to 0.083) | |
| (f) Subcostal, 2 cm, best image | 0.53 (0.36 to 0.71) | 0.56 | 0.034 (-0.174 to 0.241) | |
| (g) Left lobe, 2 cm, best image (n=14) | 0.17 (-0.26 to 0.61) | 0.18 | 0.036 (-0.296 to 0.369) | |
| (h) Each measurement in a different locationb) | 0.81 (0.72 to 0.89) | 0.81 | 0.009 (-0.108 to 0.125) | |
| (i) Free breathing, intercostalb) | 0.81 (0.73 to 0.89) | 0.82 | 0.002 (-0.130 to 0.134) | |
ATI, attenuation imaging; ROI, region of interest; CCC, concordance correlation coefficient; CI, confidence interval.
a)
The position refers to the upper edge of the ROI with respect to the liver capsule.
b)
ROI at 2 cm, best image.