Airway measurement using morphometric analysis

Measurement of airway size using endoscopic morphometry was investigated. Endoscopic images of the porcine tracheobronchial tree were obtained via a Storz system at a known distance from the telescope. The bronchi were marked with transluminal wires, transected, and imaged. All images were analyzed morphometrically with a computer image at multiple sites (N = 20). The endoscopic measurements were plotted against the macro lens images so that a straight line with a slope of 1 would indicate a consistent correlation. Area measurements for all images had a slope of 0.67 (r = .885); however, for images with area < 80 mm² the slope was 1 (r = .928) and for images with area > 80 mm² the slope was −0.63 (r = .757). Minor axis measurements had a slope for all images of 0.71 (r = .879), for images with area < 80 mm² of 0.93 (r = .875), and for images with area > 80 mm² of −0.34 (r = .482), and major axis had a slope for all images of 0.73 (r = .904), for images with area < 80 mm² of 0.88 (r = .923), and for images with area > 80 mm² of−0.59 (r = .771). Accurate area measurements as well as major and minor axis measurements can be obtained for airways with area < 80 mm² by means of this system. Each bronchoscope-telescope unit has an optimal target size for which measurements are accurate.