选择MSCT肺动脉血管成像触发点位置及后处理技术

Choice of triggering position and post-processing technique in multi-slice CT pulmonary angiography

目的探讨肺动脉CT血管成像（CTPA）时触发点位于上腔静脉的应用价值以及不同图像后处理技术的选择。方法疑诊肺动脉栓塞（PE）拟接受CTPA检查的患者40例分成A、B两组,A组触发点感兴趣区（ROI）位于肺动脉干,阈值80 HU,对比剂总量50-60 ml,B组ROI位于主动脉窗水平的上腔静脉内,阈值80 HU,对比剂总量35-45 ml,两组的其他技术参数相同。分析两种方法的CTPA图像,测量肺动脉干、右下肺静脉CT值及6级肺动脉显示率,进行统计学分析,同时比较各种后处理重组方法对栓子的显示率。结果 40例疑似PE患者,除B组1例严重的右心功能不良致肺动脉图像较差外,其余均得到满意的图像;肺动脉干CT值和6级肺动脉的显示率两组差异均无统计学意义（P均〉0.05）;右下肺静脉CT值B组明显低于A组,差异有统计学意义（P=0.04）;各种不同后处理技术,对不同情况下的栓子显示,各有其优势。结论选择触发点位于上腔静脉的CTPA检查方法,能减少对比剂的用量和提高图像的质量;各种后处理技术的综合运用,能更好地显示病变和提高诊断的准确性。

Objective To evaluate the clinical application of triggering position located at superior vena cava and to choose the different post-processing techniques in CT pulmonary angiography（CTPA）.Methods Forty patients with suspected pulmonary embolism（PE） were divided into group A and B.For group A,the region of interest（ROI） of triggering position located at pulmonary artery trunk,the threshold was 80 HU and the dose of contrast medium was 50-60 ml.For group B,the ROI located at superior vena cava,the dose of contrast medium was 35-45 ml and other parameters were as same as group A.CTPA images of the two methods were analyzed.Densities of pulmonary artery trunk and right lower pulmonary vein were measured,the ratios of the displayed 6th grade pulmonary artery was calculated and the results were statistically analyzed.The ratios of different post-processing techniques in displaying embolism were compared.Results All CTPA images were satisfactory except one patient with severe right ventricular dysfunction in group B.The densities of pulmonary artery trunk and the displaying ratios of the 6 th grade pulmonary artery showed no significant difference between the two methods,but significant difference existed in the densities of right lower pulmonary vein（P=0.04）.Different post-processing techniques had their own advantages in displaying different kinds of embolism.Conclusion CTPA examination with triggering position located at superior vena cava can decrease the dose of contrast medium and improve the quality of images.Combination of different post-processing techniques can display the embolism better and improve the accuracy of diagnosis.