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

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. RESULT: 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. CONCLUSION: 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.

[Flow simulation of normal pulmonary artery branches based on CT image].

OBJECTIVE: To study the hemodynamics of the pulmonary artery (PA) in pulmonary artery hypertension (PAH). METHODS: With combined clinical hemodynamic measurements and CT data, the 3D model of PA and its branches was reconstructed to obtain the real 3D geometric structure of PA and its branches. Computational fluid dynamics (CFD) simulation was carried out for the reconstructed 3D geometric model of the PA and its branches with Womersley velocity as main pulmonary entrance conditions; then hemodynamic parameters of the PA and its branches in cardiac cycle were calculated and the changes of flow field, pressure, wall shear stress (WSS) at different times, and its impact on physiological processes were analyzed. RESULT: Simulation showed that the pressure of the main PA and the branches of the left and right PA was higher in the systolic period than that in the diastolic period; especially, the that of right PA and its interlobular artery was significantly higher than that of the left. The blood flow velocity of the main PA and its branches of right and left PA was significant different, the velocity was much higher at the distal of the right PA than that at the left. High WSS field formed at the proximal of the right PA before the branches during the systolic. CONCLUSION: The right PA at the proximal and lower lobe artery are affected by much larger pressure and change firstly, so the change of morphological and functional of theses segments will be have more important value to prompt existence of the early PAH.

[Flow simulation of normal pulmonary artery branches based on multiple detectors computed tomography].

OBJECTIVE: To simulate the flow condition in the main pulmonary artery and the branches of left and right pulmonary arteries by combining the images from CT pulmonary angiography (CTPA) by multiple detectors computed tomography (MDCT) and the flow condition data from ultrasonic cardiography. METHODS: The normal enhanced chest CTPA images with ECG-gating from 25 persons undergoing physical examination, 21 males and 4 females, aged 39, underwent thin-slice multiple plane reconstruction in diastolic and systolic periods respectively. These images were stored in the InSpace software. On the base of coordinates GAMBIT software was used to generate the nodes and meshes. FLUENT software was used to simulate the blood flow speed and pressure field distribution. RESULTS: The pressure levels of the main pulmonary artery and the branches of left and right pulmonary arteries were higher during the systolic period. The blood flow velocity was faster during the systolic period too. The right lower lobe artery endured the most significant pressure during both systolic and diastolic periods. However, there were not significant differences in pressure and blood flow velocity between the systolic and diastolic periods in the segmental arteries. CONCLUSION: The right lower lobe artery is the first part to be affected when the pulmonary pressure rises. It is feasible to study the changes of the flow condition in the branches of pulmonary artery through combining CTPA images and relevant softwares.