双源CT低剂量扫描联合迭代重建在主动脉夹层中的应用

Application of Dual-source CT Low-kv combined with Iteration Reconstruction in Aortic Dissection

目的探讨双源CT低kv联合迭代重建技术(IR)对降低主动脉夹层患者的辐射剂量及图像质量的影响。方法对临床拟诊主动脉夹层的60例次患者行双源CTA检查,按照先后顺序将患者分为A组:常规剂量组120 kv,n=20、B组:低剂量100 kv,n=20、C组:低剂量80 kv,n=20。120 kv采用传统滤波反投影(FBP)重建作为对照组,低剂量扫描组分别采用FBP及IR对图像进行重建。并由两名有经验的医师对3组图像质量进行评价。比较不同kv和重建算法的有效剂量(ED)、背景噪声(BN)、对比信噪比(CNR)、信噪比(SNR)以及图像质量。结果低剂量100 kv组(10.56±0.42)m Sv和80 kv(5.05±0.17)m Sv组有效剂量较对照组(16.12±0.55)m Sv分别降低34.5%、68.6%。100 kv、80 kv采用IR组较同一剂量FBP组BN分别降低36.2%、28.3%,CNR及SNR分别提高57.7%、58.0%;36.1%、41.7%,组间比较均有统计学意义。随着管电压降低,主动脉CT值增高,100 kv IR组及80 kv IR组较对照组CNR及SNR升高,P<0.05。结论与120 kv FBP相比,100 kv和80 kv采用IR技术能使有效辐射剂量分别降低34.5%、68.6%,同时不影响图像质量。

Objective To evaluate radiation dose and image quality of dual-source CT aorta dissection with iterative reconstruction technology and low k V. Methods Sixty patients clinically suspected of aortic dissection were performed dual-source CT aorta angiography（ CTA）.They were randomly divided into three groups ：group A（standard dose protocol 120 kv,n=20）;group B（low-dose protocol 100 kv,n=20）;group C（low-dose protocol 80 kv,n=20）.Images from control group were reconstructed by FBP,and low-dose groups were reconstructed by FBP and IR.I mage quality wes scored subjectively by two experienced radiologists.Background noise,signal-to-noise ratio（SNR）,contrast-to-noise ratio（CNR） and the radiation dose were compared and analyzed statistically. Results The mean effective radiation dose in low-dose groups 100 kv（10.56±0.42）m Sv and 80 kv（5.05±0.17）m Sv was reduced by 34.5% and 68.6% respectively compared with control group（16.12±0.55）m Sv.BN in 100 kv IR、80 kv IR groups compared with alike dose FBP group was reduced respectively 36.2% and 28.3%. CNR and SNR was improved respectively 57.7%、58.0% and 36.1%、41.7%（P 0.05）.The CT value of aorta was rised obviously with the decrease of KV.SNR and CNR of low-dose groups reconstructed with IR were improved obviously,compared with control group. Conclusion Compared with 120 kv FBP, 100 kv and 80 kv groups with IR technique could maintain or improve image quality of aorta dissection,while radiation dose reduced 34.5% and 68.6% respectively.