Figures
- Fig. 1—
Sites of airway–artery measurements shown on a bronchial tree. This bronchogram clearly demonstrates the divisions of the airway tree where the measurements were performed on computed tomography for the present study. A: trachea, lumen area and wall area; B: right bronchus intermedius, lumen and wall area; C: right apical bronchus (RAB), lumen and wall area and arterial area; D: first branch after RAB, lumen and wall area and arterial area; E: second branch after RAB, lumen and wall area and arterial area; F: third branch after RAB, arterial area.
- Fig. 2—
Computed tomography (CT)-measured lung weight and predicted lung weight versus subjects' height. Subjects' height at ∼2 yrs (#) and 8 yrs (¶) of age is indicated by the vertical dotted lines. ♦: CT-measured lung weight. ———: predicted lung weight from published data on autopsy specimens 42. The equation for the regression is: CT measured lung weight = 35.1×expsubject height×0.0183 (R2 = 0.96, p<0.0001).
- Fig. 3—
Computed tomography measured lung expansion at total lung capacity (TLC) versus subjects' height. The data from males and females were grouped for calculation of the regression equation due to small sample size. Subjects' height at ∼2 yrs (#) and 8 yrs (¶) of age is indicated by the vertical dotted lines. •: females; □: males. -----: 95% confidence intervals calculated for males and females together. The equation of the regression is: expansion at TLC = 0.172×height0.735 (R2 = 0.66, p<0.001).
- Fig. 4—
a) Measurements of lumen area for trachea (⋄) and right bronchus intermedius (RBI; ▪) are plotted against the subject height. The power-law regression lines are shown for the trachea (––––) and the RBI (-----). The 95% confidence intervals are not shown. b) Measurements of lumen area for right apical bronchus (RAB; •), first branch after RAB (□) and second branch after RAB (▴) are plotted against the subject height. The linear regression lines are shown for RAB (––––), RAB1 (------) and RAB2 (········). The 95% confidence intervals are not shown. The linear regression lines and corresponding equations are provided for each generation in table 3. The data were grouped for males and females due to small sample size. Subjects' height at ∼2 yrs (#) and 8 yrs (¶) of age is indicated by the vertical dotted lines.
- Fig. 5—
Alveolar surface area/lung volume ratio versus airway lumen perimeter/airway lumen area ratio. a) Measurements of lumen perimeter/area ratio for trachea (▪) and right bronchus intermedius (RBI; ⋄) are plotted against the lung surface area/volume ratio. The regression line is shown for the trachea (––––) and the RBI (------). The 95% confidence intervals are not shown. b): Measurements of lumen perimeter/area ratio for right apical bronchus (RAB; •), RAB1 (□) and RAB2 (▴) are plotted against the lung surface area/volume ratio. The linear regression line is shown for the RAB (––––), RAB1 (------) and RAB2 (········). The 95% confidence intervals are not shown. These data show that the linear dimensions of the lung parenchyma (cm−1) are linearly related to the linear dimensions of the airway (cm−1).
Tables
- Table 1—
Indications for computed tomography(CT) scan and CT scan findings
Reason for CT scan or diagnosis CT findings Subjects n Extra pulmonary tumour No metastasis 15 Solitary nodule No change in number and size 2 Mitochondrial disease Normal CT 1 Langerhans cell histiocytosis Normal CT 1 Tracheomalacia Mild malacia of the trachea 1 Vascular ring suspected No vascular ring 2 Cyst Small cyst 2 Pulmonary haemorrhage Small area with haemorrhage 2 Recovered pneumothorax No blebs 3 Upper gastrointestinal tract disorder Normal CT 3 Lupus-like syndrome Normal CT 1 Recurrent sinusitis Normal CT 3 Meckel diverticulum Normal CT 1 Foreign body suspected No foreign body 3 Sternal cleft Normal lungs 1 Cystic fibrosis <1 yr of age Normal CT 8 Haemangioma Small haemangioma 1 Of the 50 CT scans, 19 have been previously reported 28. In that report, airway wall and lumen and arterial dimensions were measured using a different measurement programme and, in that study, the normal dimensions were compared with cystic fibrosis patients.
- Table 2—
Demographics and the total lung computed tomography(CT) measurements for the study subjects
Age yrs Subjects n (male) Subjects with four images# Subject height cm CT weight g CT gas volume mL Predicted TLC mL Predicted TLC/CT weight mL·g−1 0 12 (8) 6 65±9 110±23 313±108 411±153 3.8±1.0 1 11 (8) 5 79±4 151±25 546±177 723±109 5.0±0.9 2 5 (2) 3 88±4 217±51 910±88 992±120 4.7±2.2 3 3 (3) 2 101±2 214 847 1351±41 6.1 4 1 (1) 1 115 NA NA NA NA 5 1 (1) 1 109 NA NA NA NA 7 2 (1) 0 121±6 335±141 1125±848 2170±377 6.9±1.8 9 1 (1) 0 131 365 1726 2749 7.5 10 1 (0) 0 144 449 1818 3320 7.4 11 1 (0) 0 139 564 3293 3031 5.4 12 2 (1) 0 151±1 566±58 2617±933 3855±55 6.8±0.6 13 1 (0) 0 158 598 1034 4216 7.1 14 3 (1) 0 162±16 688±187 2424±132 4691±1403 6.8±0.7 15 2 (2) 0 173±0 930±146 4565±1370 5617±0 6.1±1.0 16 1 (0) 0 157 578 2940 4148 7.2 17 3 (1) 0 167±7 711±199 2731±1052 4950±724 7.2±1.3 Data are presented as mean±sd or n unless otherwise stated. TLC: total lung capacity; NA: not assessed. #: For subjects with only four CT images per CT scan, lung parenchyma dimensions could not be estimated. No subjects aged 6 and 8 yrs were available.
- Table 3—
Power law regression equations for computed tomography estimated airway and arterial areasversus subject height
Y variable# Subjects n Sex A B Correlation R2 p-value Lumen area cm2 Trachea 48 Both 0.0003 1.64 0.90 <0.001 RBI 34 Both 0.0003 1.46 0.85 <0.001 RAB 29 Both 2×10−6 2.02 0.80 <0.001 First branch after RAB 29 Both 3×10−6 1.69 0.75 <0.001 Second branch after RAB 25 Both 5×10−7 1.94 0.77 <0.001 Wall area cm2 Trachea 48 Both 0.0016 1.27 0.87 <0.001 RBI 34 Both 0.0024 1.10 0.86 <0.001 RAB 29 Both 0.0004 1.30 0.80 <0.001 First branch after RAB 29 Both 0.0005 1.13 0.83 <0.001 Second branch after RAB 25 Both 5×10−5 1.41 0.85 <0.001 Arterial area cm2 RAB 31 Both 0.0004 1.21 0.76 <0.001 First branch after RAB 30 Both 5.6×10−5 1.53 0.73 <0.001 Second branch after RAB 46 Both 1.9×10−5 1.62 0.77 <0.001 Third branch after RAB 47 Both 4.5×10−6 1.78 0.86 <0.001 Y: the airway or artery variable (lumen, wall or artery area); A: the Y intercept; B: the slope (power law exponent) of the regression; RBI: right bronchus intermedius; RAB: right apical bronchus. #: Y = A × subject height in cm.
