ASiR-V联合低管电流技术在低剂量冠状动脉钙化积分扫描中的应用

The Application of ASiR-V and Low Tube Currentin Low-dose Coronary Artery Calcium Scoring

目的:探讨256层Revolution CT多模型迭代重建算法(ASiR-V)联合低管电流技术在冠状动脉钙化积分(CACS)扫描中对钙化积分值准确性的影响及其降低辐射剂量的价值。方法:入组志愿者98例。管电压120kV,噪声指数(NI)20,智能管电流,行常规剂量CACS扫描,并在两周内行低剂量CACS复查。常规剂量组:采用滤波反投射(FBP)算法,前置ASiR-V比例选择0%;低剂量组:采用迭代重建算法,前置ASiR-V比例选择50%。分别计算两组扫描的Agatston积分(AS)、质量积分(MS)和体积积分(VS),采用Wilcoxon秩检验比较两组钙化积分值的差异性,一致性和相关性分别采用Bland-Altman分析法和pearson相关系数;两组积分心脏病风险评估的一致性采用Kappa检验。两组扫描有效剂量、管电流及信噪比的比较采用配对t检验。结果:常规剂量组和低剂量组的AS、MS及VS无显著差异(P值分别为0.94、0.39和0.30);两组AS、MS及VS显示较好的一致性和高度相关性(r值分别为0.994、0.994和0.993);两组AS心脏风险分组的一致性较好,Kappa值为0.94;低剂量组与常规剂量组有效剂量分别为1.80±0.97mSv vs.2.60±1.08mSv(P<0.05),低剂量组辐射剂量显著降低;图像的信噪比分别为2.92±0.53HU vs.2.66±0.62 HU(P<0.05),低剂量组的图像质量优于常规剂量组有统计学意义。结论:ASiR-V联合低管电流技术,可以在不改变钙化积分值的情况下,显著降低扫描的辐射剂量,并且提高图像质量。

Purpose： To assess the accuracy of coronary artery calcium score （CACS） measuring and to analyze the radiation dose and image quality with adaptive statistical iterative reconstruction-V （ASiR-V） and low tube current technique using 256-slice Revolution CT. Methods： Ninety-eight cases underwent CACS scanning were enrolled in this study. The scanning protocol was set as： tube voltage 120kV, noise index 20HU, and with smart mA. The full dose scan was processed with Filtered back projection （FBP） technique, and the low dose CACS CT was performed by setting the ASiR-V level to 50% within two weeks. The Agatston scores （AS）, calcium volume scores （VS） and mass scores （MS） were calculated respectively. The difference of AS, CS, and MS between that obtain with full and low dose CACS CT were analyzed by Wilcoxon signed rank test. Radiation dose and SNR were assessed using paired t-test. Bland-altman analysis and pearson correlation coefficient were used to determine the agreement and correlation of AS, VS and MS between low and full dose CT. The agreement of the risk evaluation of coronary artery disease （CAD） between two scans was assessed using kappa test. Results： No significant difference of AS, MS and VS were shown between full and low dose groups, （P values were 0.94, 0.39 and 0.30, respectively）. Excellent agreement and high correlation of AS, MS and VS were found between the two scans. Kappa analysis showed excellent agreement in CAD risk evaluation between full and low dose scans （kappa=0.94）. There were statistical significant differences of the radiation dose and signal-to-noise ratio between the two groups： 1.80±0.97 mSv vs. 2.60 ±1.08mSv （P〈0.05）, and 2.92 ± 0.53 HU vs.2.66 ± 0.62 HU （P〈0.05）. Conelnsion： ASiR-V and low tube current technology can reduce the radiation dose without affecting the accuracy of coronary artery calcium scoring, and imnrove image quality of CACS.