CT study of branching characters of pulmonary small vessels

Objective: To study the branching geometry of the pulmonary small vessels in vivo by using imaging and branching geometrical methods, and to explore the branching configuration of pulmonary vessels. Methods: 2008 sets of dichotomous small pulmonary vessels were measured in chest helical CT of 63 normal cases. The expansion and asymmetrical factors were calculated, and their characteristics and correlation with the mother branches were studied. Results: The two factors in vivo had significant differences and different trends compared with those in the specimens; the average of the expansion factor was 1.0022, there was negative linear correlation between the diameter of mother branches. The asymmetrical factor had the median of 1.4938, there was a positive linear correlation between this factor and the diameter of mother branches, and this trend was most apparent when the diameter of mother branch was blow 4 mm. The asymmetrical factor became not evident when the diameter of mother branch was above 6.0 mm. when the diameter of mother branch was equal to 2.5 mm, the expansion factor quickly increased to 1.622 and the asymmetrical factor decreased to about 1.500. Conclusion: The study of the branching character of the pulmonary small vessels by using branching geometry method not only contributed to realize the configuration and distribution characters of pulmonary vessels but also had potential theoretical and practical value in setting up the mathematic and physical model of blood stream and pressure