双源CT低管电压联合迭代重建算法在冠状动脉成像中的应用研究

目的探讨80 k V低管电压联合迭代重建算法在CT冠状动脉成像中的应用价值.方法收集60例行冠状动脉检查的患者,所有患者心率均小于65次/min,体质量指数25 kg/m2,均采用Flash扫描模式,随机分为A组(120 k V)和B组(80 k V),B组根据原始数据重建方法不同分为B1组(传统滤波反投影,FBP)和B2组(正弦确认迭代重建技术,SAFIRE).主观对各组的图像质量进行评分,分析比较各组噪声(SD)、平均CT值(SI)、信噪比(SNR)、对比信噪比(CNR)和有效辐射剂量(ED)的差异.结果 A组和B2组主观图像评分差异无统计学意义(P0.05);B2组的图像噪声显著高于A组(P0.01),SNR和CNR相比无明显变化,差异无统计学意义(P0.05);B2组的图像噪声显著低于B1组(P0.01),SNR和CNR显著高于B1组(P0.01);A组平均有效辐射剂量为(7.30±0.68)m Sv,B组平均有效辐射剂量为(0.79±0.10)m Sv,B组辐射剂量明显小于A组,平均减少89%,两组比较差异具有统计学意义(P0.05).结论采用相同管电压时,与FBP算法比较,SAFIRE算法能显著改善冠脉的图像质量;对于BMI小于25 kg/m2的患者,采用80 k V管电压联合迭代重建算法可在不影响图像诊断的同时显著降低辐射剂量.

Study of Dual-source CT Coronary Angiography Using Combination of Low Tube Voltage and Iterative Reconstruction

Objective To explore the value of combination low tube voltage of 80 kV and iterative reconstruction technique in cardiac computed tomography angiography. Method Sixty patients with prospectively ECG-triggered high-pitch spiral computed tomography coronary angiography with heart rate less than 65 beats/min and body mass index (BMI) lower than 25 kg/m2. 60 cases were randomly divided into group A(120 kV),group B(80 kV). Group B was divided into group B1 ( filtered back projection, FBP ) and group B2 ( Signogram affirmed iterative reconstruction,SAFIRE) according to raw data reconstruction method. Image quality of each group was evaluate subjectively. Evaluate and compare the difference in the image noise,mean CT values(SI),signal-to-noise ratio ( SNR) ,contrast-to-noise ratio( CNR) and effective dose( ED) . Results There was no significant difference in the image quality scores between group A and group B2(P>0. 05). The noise of group B2 was significantly higher than group A(P<0. 01). There was no significant difference between SNR and CNR(P>0. 05). The noise of group B2 was significantly lower than group B1(P<0. 01). The SNR and CNR of group B2 was significantly higher than group B1(P<0. 01). The mean effective dose in group A and group B was 7. 30±0.68 mSv and 0. 79±0. 10 mSv respectively. The effective dose of group B was significantly smaller than group A. The effective dose was decreased by 89%. There was significant difference between them(P<0. 05). Conclusion Compared with FBP,SAFIRE can significantly improve the image quality of the coronary artery with the same tube voltage;For the patient with BMI lower than 25 kg/m2 ,using combination of low tube voltage and iterative reconstruction can significantly reduce the radiation dose without affecting the image diagnosis.