The airways areas were also compared to the area of an age appropriate endotracheal tube calculated from the external diameter of the tube.
For repeated airway measurements in a given dog within each experimental protocol, adjacent anatomic landmarks, such as airway or vascular branching points, were used to locate and measure the airway area at the same anatomic cross sections.
Airway area on the HRCT images was analyzed using the airway analysis module of the Volumetric Image and Display Analysis (VIDA) image analysis software package (Dept. of Radiology, Division of Physiologic Imaging, Univ. of Iowa, Iowa City, IA) as previously described and validated [14], [17].
Wall area as a percentage of total airway area (WA%), which has been associated with lung function [15], [16], was computed using a partial membership algorithm developed at the University of Pittsburgh [17], [18] and used as a measure of bronchial thickening.
Additionally, wall area was expressed as percentage of total airway area: 100 % × WA/ WA + LA) = WA%.
The airway area data was normally distributed (Kolmogorov-Smirnov); therefore unpaired T tests were used for group comparisons.
The larger FVC (≧100% of predicted FVC) influences the larger Pst (l) and the smaller airway area guides the higher Rus at the beginning of expiration.
For measurement of bronchiolar thickness, bronchiolar epithelium areas were identified on the basis of intensity; the area was then calculated by subtraction of the luminal-airway area from the total bronchiolar area.
The aims of this study were to measure large airway areas, and define proportions and factors that influence airway size in children.
The systematic review included ten CT measurements: %LAA-960, %LAA-950, %LAA-910, %LAA-900, MLD, 15 percentile point of lung density (Perc15), lung volume (LV), WA%, airway wall thickness (WT) and airway lumen area (Ai).
