多层螺旋CT对周围肺动脉显示能力的研究

CT Evaluation of Peripheral Pulmonary Arteries with Multislice CT

目的比较多层螺旋CT肺动脉造影不同层厚重建对周围肺动脉的显示能力。资料与方法21例无肺部疾患和血栓病史的患者行CT肺动脉造影检查,均用0.75 mm准直扫描,分别用0.75 mm/0.5 mm(层厚/层间距)(A组)、1.0 mm/0.6 mm(B组)1、.5 mm/1.0 mm(C组)重建,记录每例患者3种不同重建层厚对段肺动脉、亚段肺动脉5、级和6级肺动脉的显示情况及血管不能显示的原因。结果3组人均肺段动脉的显示率均为96.45%(19.29/20);人均亚段动脉显示率分别为94.42%、93.44%、91.13%,3组间均无显著性差异;A、B、C组对第5级肺动脉的人均显示率分别为80.44%、73.47%、59.02%,A组与C组有显著性差异(P<0.01),B组与C组间有显著性差异(P<0.05);6级肺动脉3组人均显示率分别为33.75%、31.69%、23.56%,A组与C组有显著性差异(P<0.01)。段肺动脉不能分析的主要原因是解剖变异(53.33%)和心脏搏动伪影(40%);A、B组亚段肺动脉不能分析的主要原因是解剖变异和心脏搏动伪影,C组的主要原因是部分容积效应(43.84%)与A组比较有显著性差异(10.87%)(P=0.015);3组对5级和6级肺动脉不能分析的主要原因均为部分容积效应。结论多层螺旋CT肺动脉造影0.75 mm1、.0 mm1、.5 mm重建层厚对段肺动脉和亚段肺动脉均有很好的显示率,A、B组对5级肺动脉的显示率也较好。影响亚段肺动脉显示的主要原因是解剖变异和心脏搏动伪影。1.0 mm重建层厚可满足肺动脉的观察和图像处理的需要。

Objective To compare the visibility of peripheral pulmonary arteries by different slice thickness reconstruction using 16-slice spiral CT pulmonary angiography. Materials and Methods 21 patients without pulmonary and thromboembolic diseases were underwent CT pulmonary angiography with 0.75mm collimation. Three different slice thickness were reconstructed from the raw data for each patient ： 0.75mm/0.5 mm（ slice thickness/increment （group A）, 1.0mm/0.6mm （ group B ）, 1.5 mm/1. 0mm （group C）. The proportion of well-visualized segmental pulmonary arteries, subsegmental pulmonary arteries, fifth-order and sixth-order pulmonary arteries in the 3 groups were recorded. The reasons for inadequate depiction of pulmonary arteries were analyzed. Results The proportion of well-visualized segmental pulmonary arteries in 3 groups was identical 96.45 %. The depiction rates of subsegmental pulmonary artries in group A, B, C were 94.42%, 93.44% and 91.13% respectively without any significant difference among the 3 groups. The depiction rates of fifth-order pulmonary arteries in the 3 groups were 80.44%, 73.47% and 59.02% respectively, and there were significant differences between group A and C （P 〈 0.01 ） and between group B and C （ P 〈 0.05 ）. The depiction rates of sixth-order pulmonary arteries in the 3 groups were 33.75 % , 31.69 %, and 23.56% respectively, and there was significant difference between group A and group C （P 〈 0.01 ）. The primary causes of inadequate depiction of segmental pulmonary arteries were anatomic variance （53.33 % ） and cardiac motion artifacts （40 % ）. The primary causes of inadequate depiction of subsegmental pulmonary arteries were anatomic variance and cardiac motion artifacts in group A and B, but partial volume effect was main reason in group C （43.84%）, which was significant higher than group A （ 10.87% ） （ P = 0.015）. The main causes of inadequate depiction of fifth and sixth-order pulmonary arteries were partial volume effect in all 3 groups. Conclusion 16-slice spiral CT pulmonary angiography with reconstructed slice thickness of 0.75mm, 1.0mm and 1.5mm is enabled to demonstrate segmental and subsegmental pulmonary arteries. The depiction rate of fifth-order pulmonary arteries is also good in group A, B. The primary causes of inadequate depiction of subsegmental pulmonary arteries are anatomic variance and cardiac motion artifacts. Reconstructed slice thickness of 1.0mm is adequate for the depiction of pulmonary arteries and the need for image processing.