Abstract

Swine are a commonly used model in translational pulmonary research. However, in vivo airway morphometry during respiration has not been studied in detail . Chest CT was performed in swine (n=3) at multiple stages of respiration. Morphometric parameters of each airway segment at end-expiration and end-inspiration were compared as well as among matched anatomical regions (proximal and distal; ventral, lateral and dorsal). Analysis included segment diameter, length, ellipticity and the bifurcation angle. Deformation of the airway during respiration was qualitatively visualized using a point-to-point deformation map. Comparison of airway generation showed airway diameter and length were larger at end-inspiration in the 4th and 7th generations compared to end-expiration. Bifurcation angle was larger at end-inspiration compared to end-expiration. Analysis by anatomical region showed that length and bifurcation angle were larger at inspiration in the distal airway regions only. Regardless of respiratory phase, the lateral regions had the largest diameters and lengths and proximal regions had larger bifurcation angles. These findings were qualitatively confirmed by analysis of a deformation map. Compared to human airway models, the relative diameter may be smaller and length may be greater in swine, in similar airway generations. This morphometric description of the swine airways during respiration may guide conduct of preclinical translational studies, revealing advantages and limitations of swine models for specific evaluations. Such morphometric parameters may directly determine the suitability of the swine model for the study of lung interventions, in terms of recapitulation of human morphometry dynamics.

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