肺小血管分支特征的CT测量研究

目的 利用影像学手段采用分支几何学方法探索在活体状态下肺小血管的分支特征。方法 通过对63例正常胸部螺旋CT扫描图像，采用分支几何学方法对2008套肺血管两分支状血管分支点两侧的血管横径进行测量，计算扩张因子和不对称因子，分析其特征及与母支直径的相关关系。结果 活体状态下两因子与标本数据存在差异；扩张因子均值为1．0022，不对称因子中位数为1．4938，分别与母支横径呈线性负、正相关，这一趋势在母支横径小于4．0mm时最为明显。母支横径大于6．0mm时，不对称因子分布趋势不明显。母支横径为2．5mm时，扩张因子迅速降至1．622，而不对称因子降至1．500左右。结论 用分支几何学方法研究肺小血管的分支特征，对认识肺血管的分支形态特点，建立血流和压力的数学及物理模型有潜在理论和实用价值。

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 2 008 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 1.002 2, there was negative linear correlation between the diameter of mother branches. The asymmetrical factor had the median of 1.493 8, 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.