Pulmonary arterial morphometry from microfocal X-ray computed tomography

The objective of this study was to develop an X-ray computed tomographic me thod for pulmonary arterial morphometry. The lungs were removed from a rat, and the pulmonary arterial tree was filled with perfluorooctyl bromide to enhance X-ray absorbance. At each of four pulmonary arterial pressures (30, 21, 12, and 5.4 mmHg), the lungs were rotated within the cone of the X-ray beam that was projected from a microfocal X-ray source onto an image inten sifier, and 360 images were obtained at 1 degrees increments. The three-dim ensional image volumes were reconstructed with isotropic resolution with th e use of a cone beam reconstruction algorithm. The luminal diameter and dis tance from the inlet artery were measured for the main trunk, its immediate branches, and several minor trunks. These data revealed a self-consistent tree structure wherein the portion of the tree downstream from any vessel o f a given diameter has a similar structure. Self-consistency allows the ent ire tree structure to be characterized by measuring the dimensions of only the vessels comprising the main trunk of the tree and its immediate branche s. An approach for taking advantage of this property to parameterize the mo rphometry and distensibility of the pulmonary arterial tree is developed.