低浓度等渗对比剂和低管电压扫描在320排CT肺动脉成像中的应用

Application of“Double low”in 320-row CT pulmonary angiography

目的探讨低浓度等渗对比剂和低管电压的"双低"模式行320排CT肺动脉成像的图像质量和辐射剂量。方法 42例行肺动脉CTA患者随机分为两组:A组20例,使用120kV管电压,优维显370mgI/ml对比剂;B组22例,采用100kV管电压,碘克沙醇270mgI/ml对比剂,其余参数设置相同。测量每例患者肺动脉主干和分支的CT值,计算图像信噪比和对比噪声比。记录设备自动生成的剂量长度乘积,计算有效剂量。应用独立样本的t检验对上述数据进行统计学分析。结果两组图像质量均符合诊断要求,两组肺动脉各段CT值、图像信噪比和对比噪声比差异均无统计学意义(P>0.05)。使用120kV组的剂量长度乘积和有效剂量高于100kV组,差异有统计学意义(P<0.05)。结论应用碘克沙醇270mgI/ml对比剂、100kV管电压结合迭代重建行320排CT肺动脉成像,图像质量能满足临床诊断要求,且有效地降低了辐射剂量。

Objective To evaluate image quality and radiation dose under low concentration of contrast agent and low tube voltage for pulmonary angiography（CTPA）by using of 320-row CT with a＂double low＂scanning protocol.Methods42 patients,who underwent pulmonary angiography（CTPA）with a 320 CT scanner,were divided into two groups randomly.20patients（group A）received 120 kV voltage and ultravist（370mgI/ml）,and the remaining 22patients（group B）received 100 kV voltage and iodixanol（270mgI/ml）.The rest of parameter settings was consistent.We evaluated the CT value of the pulmonary artery trunk and branches in each case and determined image signal-to-noise ratio（SNR）,contrast-to-noise ratio（CNR）.Then,we recorded dose length product and calculated the effective radiation dose.The all above data were subjected to statistical analsis using two independent sample t test.Results Image quality of two groups were conformed to the requirements of diagnosis.The CT value,SNR,and CNR of each pulmonary artery had no significant difference between two groups（P〉 0.05）.The dose length product and the effective radiation dose of group A were higher than group B,and there were statistically significant difference between them（P〈 0.05）.Conclusion Image quality of CTPA by the scanning protocol（100kV＋iodixanol,270mgI/ml）of 320-row CT scanner can meet the requirement of clinical diagnosis,and effectively reduce the radiation dose.