螺距的选择对胸腹主动脉夹层320层CT成像质量的影响

目的：探讨螺距的选择对320层CT螺旋扫描模式胸腹主动脉夹层图像质量及辐射剂量的影响。方法：连续纳入可疑急性主动脉综合征患者100例,分为两组,A组（50例）采用螺距为53、B组（50例）采用螺距为95进行胸腹主动脉CTA扫描。使用Toshiba Aquilion one 320 CT机,120 kV,450 mA,0.35 s/r。选用体部前置滤线器和后置过滤器,重建层厚0.5 mm。应用SPSS 11.5软件分别对A组和B组的CT有效辐射剂量、图像噪声均值进行非配对t检验。结果：A组平均有效辐射剂量为18.19 mSv,B组为9.52 mSv,较A组有效辐射剂量平均减少50%。A组患者平均扫描时间为9.5 s,B组为4.53 s,较A组扫描时间平均减少5.07 s。A组患者的对比剂总量平均为83.6 ml,B组为71.8 ml,较A组对比剂总量平均减少12 ml。结论：在进行胸腹主动脉CTA检查中管电压和管电流恒定不变的情况下选择大螺距扫描,可以减少扫描时间、对比剂量并显著降低辐射剂量,在保证图像质量的同时,主动脉根部搏动伪影减小,可显示冠状动脉开口及近段,从而达到优化图像的同时降低辐射剂量的目的。

Effect of different pitch on image quality and radiation dose in aortic CT angiography with 320-slice CT

Objective:To make a comparison of influence on imaging quality and radiation dose at different pitch scan modes for thoracic and abdominal aortic CT angiography using 320-row CT.Methods:100 Patients with acute aortic syndrome were consecutively enrolled and randomly divided into two groups.They underwent CTA of thoracic and abdominal aorta with a pitch of 53(group A,n=50),or a pitch of 95(group B,n=50).The study was performed with 320-slice CT(Toshiba,Nasu,Japan).All images were obtained at 120kV tube volta...