慢性阻塞性肺疾病肺动脉高压分支形态的影像学及流态功能改变

Image and hemodynamical features of pulmonary artery branches in COPD with pulmonary artery hypertension

目的:利用MDCT的CTPA图像和超声肺动脉测压数据,模拟分析慢性阻塞性肺疾病(COPD)肺动脉高压状态下的主肺动脉及左右肺动脉分支内流动状态;了解肺动脉分支直径随压力变化的情况和敏感度。方法:选择符合临床诊断标准的COPD患者,进行胸部心电门控CTPA检查,同时收集超声心动图测量主肺动脉及左右肺动脉近端双期血流参数。对CTPA原始图像分别进行心脏收缩期及舒张期薄层MPR重建,测量肺动脉分支的直径和长度;利用坐标网格,生成二维网格,导入Fluent软件进行数值计算和二维流态模拟。结果:共进行13例COPD患者研究,CTPA显示,主肺动脉分叉前和左、右肺动脉近端直径在收缩期均较舒张期小。右上叶前段动脉舒张期直径较收缩期增大,主肺动脉/左、右肺动脉的长度在收缩期和舒张期都无显著性差异,而主肺动脉右肺动脉的弯曲度和跨度间距在舒张期均较收缩期增大。COPD比较正常对照组的右肺动脉近端、远端及左肺动脉近端,在收缩期和舒张期直径均增大,且存在显著性差异,舒张期仅主肺动脉分叉前出现直径增大;收缩期后基底段动脉,左后基底段动脉COPD组较正常变细;两组间长度未见显著性差异。流态分析显示,COPD舒张期高压场较正常组扩散的趋势更明显,影响范围更大。右下叶动脉出口压力收缩期最高,舒张期也较左下叶动脉高,是所有动脉出口中承受压力最高且波动最大者,出口流速变化差异最大。结论:利用CTPA重建MPR图像和相关模拟软件结合,是研究肺动脉分支内血流变化的可行方法。CTPA测量右肺动脉远端直径可能成为肺动脉高压诊断的新指标。

Objective: To investigate the imaging and hemodynamical features of pulmonary artery branches in chronic obstructive pulmonary disease(COPD) with pulmonary artery hypertension(PAH).Methods: CT pulmonary angiography(CTPA) with ECG-gating was performed in 13 patients with clinical diagnosed COPD and 25 normal subjects.The thin-slice multiple plane reconstruction in systole and diastole phase was conducted,which in turn was used to generate the InSpace reconstructed images with reference frame of the main pulmonary artery and the first two grades branches,the contour of the branches was depicted.On the base of coordinates,the GAMBIT was used to generate nodes and furthermore meshes,then the software Fluent was used for numerical calculation and flow simulation.The velocity and pressure changes in the main pulmonary artery and the first two grades branches during different periods of cardiac cycle were observed in both groups.Results: CTPA showed that the diameter of the main pulmonary before bifurcate and proximal of the first two branches was larger in systole period than that in diastole period.The diameter of the second segmental artery of right upper lobe was larger during diastole period.The length of the main pulmonary and the first two branches showed no significant difference in both diastole and systole periods.There was no significant difference in length of pulmonary arteries between COPD and normal groups.The main pulmonary to distal right pulmonary artery appeared larger in diastole period.Compared with normal,in COPD group several arteries increased in diameter including proximal and distal of the proximal right pulmonary artery and the proximal right pulmonary artery during systole and diastole periods.In systole period only the diameter of the main pulmonary before bifurcate got larger and the back basic segmental artery of both lower lobe show smaller than normal.The flow condition analysis in COPD and normal groups suggested higher pressure in pulmonary arteries during systole period than that in diastole period,both groups showed high pressure area below the branching point.In COPD patients the right lower lobe artery endured the most significant pressure fall during the two periods and high pressure distributed larger area than normal.Flow velocity in main branch was faster than lower grade branches and that in systole period was faster than that in diastole period.The trend of diffusion of high pressure area was more prominent in diastole period than normal and the influence more prominent.Conclusions: The distal part of right pulmonary artery to lower lobe artery may be affected earlier when the pulmonary pressure increased.It is feasible to study the changes of flow condition in pulmonary artery branches though the combination of CTPA image and relevant software.