迭代重建算法在超重患者640层CT冠状动脉成像中的应用研究

Application of 3D adaptive iterative dose reduction in coronary CT angiography with 640-slice CT scanner for overweight patients

目的探讨三维自适应迭代剂量降低算法(3D AIDR)对超重患者640层冠状动脉CT血管造影(CTA)的图像质量及辐射剂量的影响。方法连续80例疑似冠心病的超重患者(30kg/m^2≥BMI≥25.0kg/m^2)以随机数字表法分成A、B两组,行前瞻性心电门控扫描。A组以120 kV管电压扫描,原始数据分别以FBP(A1组)和3D AIDR(A2组)重建图像;B组以100 kV管电压扫描,原始数据以FBP(B1组)和3D AIDR(B2组)重建图像。2位放射科医师以5分法评价15个冠状动脉节段的图像质量。比较A组和B组各亚组间的噪声(SD)及平均CT值(Si)、信噪比(SNR)、对比信噪比(CNR)和有效辐射剂量。结果 B组有效辐射剂量较A组减少了46%。A组和B组各亚组间的图像质量得分差异均有统计学意义(均P<0 05),A1与B2组的图像质量得分差异无统计学意义(P>0.05)。A组各亚组间SD、SNR、CNR比较差异均有统计学意义(均P<0.05)。B组各亚组间SD、SNR、CNR比较差异均有统计学意义(均P<0.05),B2组与A1组SI差异有统计学意义(P<0.05),SD、SNR、CNR差异均无统计学意义(均P>0.05)。结论 3D AIDR联合100kV低剂量扫描在保持适合诊断的冠状动脉图像质量的同时能大幅度降低CTA辐射剂量。

Objective To investigate the image quality and radiation dose of CT coronary angiography using 3D adaptive iterative dose reduction in overweight patients. Methods Eighty consecutive overweight patients with suspected coronary artery disease underwent coronary CT angiography with 640- slice CT scanner, the patients were randomly divided into two groups：the tube voltage was 120 kV in group A and 100 kV in group B. Al raw data were reconstructed by software FBP and 3D AIDR in CT system and two new subgroups in group A and B were created （A1, A2 and B1, B2）, respectively.The values SI, SD, SNR, CNR, and image quality scores were compared between subgroups A1 and A2, and subgroups B1 and B2. The values of SI, SD, SNR, CNR and image quality scores were also compared between B2 and A1. Results The value of E in group B was decreased by 46%compared to group A.There was significant difference in mean image quality scores between groups A1 and A2 （P〈0.05） and between groups B1 and B2 （P〈0.05）. There was no significant difference in mean image quality scores between groups A1 and B2. The values of SD in group A1 were significantly higher and SNR and CNR were lower than those in group A2 （P〈0.05）. The values of SD in group B1 were significantly higher and SNR and CNR were lower than those in group B2（P〈0.05）. There was significant difference in SI between group A1 and group B2 （P〈0.05）, but no difference in SD, SNR, CNR between two groups （P＆gt;0.05）. Conclusion The 3D AIDR reconstruction algorithm can significantly improve the image quality of coronary artery in the equivalent dose, which are helpful for the image interpretable in the low dose for overweight patients.