PNNL

Abstract

Abstract In this study, we present an automated method for tabulating geometric information of biological trees, based on magnetic resonance imaging data of silicone casts of the pulmonary airway trees of Sprague Dawley rats. From a segmentation of the airway tree, we construct a scale-invariant triangulated surface that is subsequently distilled into a connected graph, representing the airway centerline. Segment statistics are derived from this graph. To validate the method, these statistics are compared to manual measurements of a single lung cast. Subsequently, we analyze the morphometry of the airway tree by assembling individual airway segments into structures that span multiple generations, which we call branches. We show that branches not segments are the fundamental repeating unit in the rat lung and develop a parameterization of these structures for the entire lung. Our analysis shows that airway diameters and lengths have both a deterministic and stochastic character and can be described by a simple set of equations.