螺旋CT肺血管三维成像的实验研究

THE EXPERIMENTAL STUDY ON SPIRAL CT THREE DIMENSIONAL PULMONARY ANGIOGRAPHY

为了设计螺旋CT三维血管成像的合理扫描条件、重建方法，探讨其肺血管三维成像的显示级别和伪影的形成机制、影响因素，对离体人、狗心肺各两具行肺血管灌注后充气，当pitch为1时，观察不同层厚、FOV和重建间隔对用表面覆盖法进行肺血管三维成像的影响。结果：①扫描层厚越薄，FOV越小，重建间隔适当缩小，肺血管的显示级别升高。②阶梯伪影由不连续内插算法引起，与床进速度和重建间隔有关。③拉长伪影决定于层敏感性，受床进速度、pitch和内插算法影响。表明螺旋CT肺血管三维成像受诸多成像因素影响，需合理选择。

To design equitable technical factorsof spiral CT study the mechansim and influential elements of artifact and the displayed grades of threedimensional pulmonary vessels, we inflated thelungs which were drawn from fresh cadavers (n=2)and living dogs (n=2) with air after Pouring contrast into pulmonary arteies. When pitch was 1, weexamined the influence of different collimations, foons of view (FOV) and reconstruction intervals onangiography with threshold shaded surface display(SSD). Results: 1. Thin collimation, small FOVand suitable narrow reconstruction interval displayed high grade of pulmonary vessels. 2. Thestair-step artifact resulted from discontinuous interpolation geometry. It related to the table incrementand reconstruction interval. 3. The drag-tail artifactwas determined by the section sensitivity. It relatedto the table increment. interpolation algorithm. Sothe technical factors of spiral CT should be chosenequitably in three dimensional pulmonary angiography.