MDCT-based quantification of porcine pulmonary arterial morphometry and self-similarity of arterial branching geometry.

The pig is frequently used as an experimental model for studies of the pulmonary circulation, yet the branching and dimensional geometry of the porcine pulmonary vasculature remains poorly defined. The purposes of this study are to improve the geometric definition of the porcine pulmonary arteries and to determine whether the arterial tree exhibits self-similarity in its branching geometry. Five animals were imaged using thin slice spiral computed tomography in the prone posture during airway inflation pressure at 25 cmH2O. The luminal diameter and distance from the inlet of the left and right pulmonary arteries were measured along the left and right main arterial pathway in each lung of each animal. A further six minor pathways were measured in a single animal. The similarity in the rate of reduction of diameter with distance of all minor pathways and the two main pathways, along with similarity in the number of branches arising along the pathways, supports self-similarity in the arterial tree. The rate of reduction in diameter with distance from the inlet was not significantly different among the five animals (P > 0.48) when normalized for main pulmonary artery diameter and total main artery pathlength, which supports intersubject similarity. Other metrics to quantify the tree geometry are strikingly similar to those from airways of other quadrupeds, with the exception of a significantly larger length to diameter ratio, which is more appropriate for the vascular tree. A simplifying self-similar model for the porcine pulmonary arteries is proposed to capture the important geometric features of the arterial tree.

An in-vivo computed tomography approach for quantifying porcine pulmonary arterial morphometry.

The objective of this study was to develop an in vivo CT imaging-based approach for pulmonary arterial morphometry measurement, and to improve the geometrical basis for studies of the porcine vasculature. The luminal diameter and distance from the inlet of left and right pulmonary arteries, and pulmonary arteries within the lungs of two porcine subjects were measured at inflation pressure of 25 cmH(2)O. The results suggest that the porcine pulmonary arteries have geometric self-similarity, and that this approach will have utility for systematically quantifying pulmonary arterial vessel dimensions in vivo in a larger group of animals.