不同噪声指数和低浓度对比剂联合ASiR-V算法用于CCTA成像的应用分析

Different NI values and low concentration contrast medium combined with ASiR-V algorithm for CCTA

目的探讨在保证冠状动脉CT成像质量基础上寻找合适的噪声指数(NI)以有效减少辐射剂量。方法收集临床上疑诊为冠心病患者100例,随机分为5组行CCTA扫描,应用造影剂Visipaque(270mg/mL)及100 Kev管电压扫描,分别设置NI 15.0、17.0、19.0、21.0、23.0。采用自适应迭代重建算法(ASi RV)进行重建。用统计分析软件对各组患者的辐射剂量和图像质量进行分析和比较。结果在对比剂浓度及管电压一定时,随着NI值的增加,平均容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效辐射剂量(ED)逐渐降低,NI 15.0、17.0、19.0组间CTDIvol、DLP、ED差异有统计学意义(P<0.05)。NI 19.0组辐射剂量(CTDIvol、ED、DLP)较NI 15.0、NI 17.0组降低较明显(P<0.05)。噪声(SD)随着NI的增高而增高;反之,信噪比(SNR)、对比噪声比(CNR)随着NI的增高而降低,NI 17.0、19.0、21.0组间SD、SNR、CNR差异无统计学意义(P>0.05)。主动脉窦及右冠状动脉(RCA)近段、左前降支(LAD)近段、左回旋支(LCX)近段的平均CT值在5组间差异无统计学意义(P>0.05)。NI 15.0、17.0、19.0、21.0、23.0组间RCA、LAD、LCX主观评价差异有统计学意义(P<0.05)。图像质量主观评分在NI 21.0和23.0组较NI 15.0、NI 17.0和NI 19.0组降低(P<0.05)。结论 NI为19.0时,应用低浓度造影剂并结合ASiR-V算法行冠状动脉CT血管造影,其在有效降低辐射剂量的同时保证图像质量是可行的。

Objective To investigate the appropriate noise index（ NI） values for effective reducing the radiation dose while maintaining the quality of CT images of coronary arteries. Methods A hundred patients with clinically suspected coronary heart disease from October to December in 2017 with CCTA scanning were randomly divided into 5 groups. We adjust different value of noise index（ NI） when evaluating each group every other number from 15. 0 to 23. 0,with twenty patients in each group. Contrast agent Visipaque（ 270 mg/m L） was applied and tube voltage was set at100 Kev. All raw data were reconstructed with adaptive statistical iterative reconstruction-V（ ASi R-V,50%）. Statistical software was used to analyze and compare the radiation dose and image quality among the groups. Results When the contrast media concentration and tube voltage were fixed,as the NI value increases,the CTDIvol,DLP and ED were gradually reduced. There was a statistically significant difference among the 5 groups（ P〈0. 05）. The radiation dose（ CTDIvol,ED,DLP） at NI 19. 0 was significantly lower than the Group NI 15. 0 and NI 17. 0. The SD increased with the increase of NI. On the contrary,the SNR and CNR decreased with the increase of NI. There was significant differences in SD,SNR and CNR among the 5 groups（ P〈0. 05）. There were no significant differences in the CT values of the aortic sinus and the three major coronary arteries among the 5 groups（ P〈0. 05）. There were significant differences in image quality subjective evaluation among the 5 groups（ P〈0. 05）. Image quality subjective evaluation were reduced in the Group NI 21. 0 and 23. 0. Conclusion Low concentration contrast agents and NI 19. 0 value combined with ASi R-V in coronary CT imaging reduces the dose of radiation while ensuring the image quality.