Figures
- FIGURE 1
a) Sagittal slice of lungs during complete expiration. b) Graph plotting volume against time. The red plot is an example of what the pneumotachograph measured during the expiration manoeuvre, first tidal breathing for approximately 30 s followed by a maximum expiration (residual volume level) with a breath hold (plateau in the curve) for a few seconds. During the breath hold, the expiration scan was acquired. The green plot is an example of what the pneumotachograph measures during the inspiration manoeuvre, first tidal breathing for approximately 30 s followed by a maximum inspiration (total lung capacity level) with a breath hold for a few seconds. During the breath hold, the inspiration scan was acquired. c) Sagittal slice of the lungs during complete inspiration.
- FIGURE 2
Comparison of the means of computed tomography (CT) to body plethysmography measurements. Grey bars represent CT-derived measurements, while white bars represent body plethysmography-derived measurements. a) Comparison of total lung capacity (TLC), b) comparison of residual volume (RV), c) comparison of % RV/TLC and d) comparison of emphysema scores at −950 HU. All comparisons are significant. Error bars represent 1 sd.
- FIGURE 3
Bland–Altman plots comparing computed tomography (CT) and body plethysmography-derived analogous measurements. a) Total lung capacity (TLC) gated, b) TLC non-gated, c) TLC % predicted gated and d) TLC % predicted non-gated. The continuous lines indicate the mean difference between CT and body plethysmography, the outer dashed lines indicate the 95% confidence intervals in the differences between CT and body plethysmography, and the difference between these is the difference in limits of agreement (ΔLoA). The finer dashed lines in the middle of the figures indicate the linear regression signifying the proportional bias.
- FIGURE 4
Bland–Altman plots comparing Computed tomography (CT) and body plethysmography-derived analogous measurements. a) Residual volume (RV) gated, b) RV non-gated, c) RV % predicted gated and d) RV % predicted non-gated. The continuous lines indicate the mean difference between CT and body plethysmography, the outer dashed lines indicate the 95% confidence intervals in the differences between CT and body plethysmography, and the difference between these is the difference in limits of agreement (ΔLoA). The finer dashed lines in the middle of the figures indicate the linear regression signifying the proportional bias.
- FIGURE 5
Figures show association of computed tomography (CT) with body plethysmography-derived analogous measurements. a) Total lung capacity (TLC) gated, b) TLC non-gated, c) residual volume (RV) gated and d) RV non-gated. All correlations are significant (p<0.001). The dashed lines indicate the line for identity and the continuous lines show the functions derived by linear regression.
Tables
- TABLE 1
Baseline characteristics
Characteristics Gated Non-gated p-value Subjects n 100 100 Female/male % 68/32 73/27 0.535# Age years 62±7 62±8 0.918 BMI kg·m−2 23.6±4.1 24.7±4.2 0.124 GOLD 2/3/4 3/37/60 3/43/54 0.723# Spirometry FEV1 L 0.81±0.27 0.79±0.24 0.464 FEV1 % predicted 29±9 29±9 0.923 FVC L 2.73±0.77 2.53±0.78 0.074 FVC % predicted 76±15 72±18 0.107 FEV1/FVC % 30±6 32±6 0.067 VC L 2.98±0.73 2.90±0.81 0.416 Body plethysmography TLC L 7.64±1.45 7.36±1.47 0.169 TLC % predicted 134±13 132±13 0.352 RV L 4.64±1.09 4.45±1.04 0.206 RV % predicted 217±39 212±40 0.408 RV/TLC % 60.6±7.3 60.4±7.5 0.884 Computed tomography Emphysema score −950 HU % 34.3±9.1 31.7±9.7 0.044 TLC L 7.37±1.45 6.78±1.48 0.005 TLC % predicted 129±12 122±14 <0.001 RV L 4.94±1.10 5.14±1.29 0.227 RV % predicted 231±39 245±48 0.024 RV/TLC % 67.2±8.4 76.2±11.7 <0.001 Table contains information, mean±sd and a p-value based on an independent t-test, for the studied population. The population is divided into two groups, gated (n=100) and non-gated (n=100). All CT-derived values are significantly different between groups, except for RV. Bold denotes a significant p-value (p<0.05). BMI: body mass index; GOLD: Global Initiative for Chronic Obstructive Lung Disease; FEV1: forced expiratory flow in 1 s; FVC: forced vital capacity; VC: vital capacity; TLC: total lung capacity; RV: residual volume. #: the test applied was the Fisher's exact test.
Supplementary Material
Please note: supplementary material is not edited by the Editorial Office, and is uploaded as it has been supplied by the author.
Supplementary material 00492-2021.SUPPLEMENT
Supplementary material ONLINE_SUPPLEMENT_SETUP_GATING
