容积CT结合ECG剂量调节在主动脉夹层中的应用

Application of volume CT angiography of the aorta in combination with ECG-controlled dose modulation in aortic dissection

目的:探讨256层CT回顾性心电门控全主动脉CT血管成像结合ECG剂量调节技术在主动脉夹层中的应用价值。方法:对58例主动脉夹层患者(ECG剂量调节组,A组)行回顾性心电门控全主动脉CT血管成像,检查时开启ECG剂量调节技术,最大剂量窗设在45%R-R间期,行45%R-R间期重建,并与72例行非心电门控全主动脉CT血管成像的患者(对照组,B组)比较,比较两组患者主动脉根部区域图像质量、第1内膜撕裂口显示情况及患者接受的有效剂量。结果:回顾性心电门控CTA对所有夹层患者均作出了准确的分型,对真腔和假腔形态、夹层累及范围及分支血管情况均准确显示。主动脉根部区域评分A组为(1.40±0.59)分,B组为(2.63±0.49)分,二者比较有显著统计学差异。在横断面图像上,第一破口A组显示明确51例,不明确7例;B组显示明确60例,显示不明确12例,二者比较无显著统计学差异。有效剂量A组为(11.15±3.51)mSv,B组为(15.16±1.31)mSv,二者比较有显著统计学差异,A组低于B组。结论:对主动脉夹层患者可选用回顾性心电门控全主动脉CTA结合ECG剂量调节技术,既能保证图像质量,充分显示主动脉夹层情况,又能降低辐射量。

Objective：To investigate the value of retrospective ECG-gated whole aortic CT angiography （CTA） using 256 slice CT,in combination with ECG-controlled dose modulation in patients with aortic dissection （AD）. Methods： 58 ca- ses with AD （ECG-controlled dose modulating group,group A） underwent retrospective ECG-gated whole aortic CTA in combination with ECG-controlled dose modulation. The maximal exposure time was set at 45 %R-R interval and reconstructed at 45 %R-R interval. The control group （group B） included 72 cases with AD undergoing non-ECG-gated aortic CTA. The image quality of the aortic root region, demonstration of the first intimal tear and the effective dose （ED） were compared between the two groups. Results： All cases with AD in group A were accurately classified according to Stanford system on CTA images,the shape of the true lumen and false lumen, the extent of AD and the involvement of vascular branches were accurately demonstrated. The score of the aortic root region was 1.40±0.59 and 2.63±0.49 in group A and group B respectively, with statistically significant difference. On axial images, the first intimal tear was clearly demonstrated in 51 cases and unclearly in 7 cases in group A whereas which was clearly demonstrated in 60 cases and unclearly in 12 cases of Group B,with no statistically significant difference. The effective dose in Group A and B was （11. 15 ±3. 51）rosy and （15.16±1. 31）mSy respectively, with statistically significant difference. Conclusion： For patients with AD, retrospective ECG-gated whole aortic CTA in combination with ECG-controlled dose modulation should be the modality of choice,which can not only guarantee the quality of the images,demonstrate AD adequately, but also reduce the radiation dose.