Department of Radiology, Cardiac Imaging, University Hospital Zurich, Ramistrasse 100, NUK C 32, CH-8091 Zurich, Switzerland.
Eur Heart J. 2011 Aug;32(15):1865-74. doi: 10.1093/eurheartj/ehr157. Epub 2011 May 5.
Coronary artery calcium (CAC) scoring has emerged as a tool for risk stratification and potentially for monitoring response to risk factor modification. Therefore, repeat measurements should provide robust results and low inter-scanner variability for allowing meaningful comparison. The purpose of this study was to investigate inter-scanner variability of CAC for Agatston, volume, and mass scores by head-to-head comparison using two different cardiac computed tomography scanners: 64-detector multislice CT (MSCT) and 64-slice dual-source CT (DSCT).
Thirty patients underwent CAC measurements on both 64-MSCT (GE LightSpeed XT scanner: 120 kV, 70 mAs, 2.5 mm slices) and 64-DSCT (Siemens Somatom Definition: 120 kV, 80 mAs, 3 mm slices) within <100 days (0-97). Retrospective intra-scan comparison revealed an excellent correlation. The excellent intra-scan (inter-observer) agreement was documented by narrow limits of agreement and a correlation coefficient of variation (COV) of r ≥ 0.99 (P < 0.001) for all CAC scores with a low COV for both scanners (64-MSCT/64-DSCT), i.e. Agatston (2.0/2.1%), mass (3.0/2.0%), and volume (4.7/3.9%). Inter-scanner comparison revealed larger Bland-Altman (BA) limits of agreement, despite high correlation (r ≥ 0.97) for all scores, with COV at 15.1, 21.6, and 44.9% for Agatston, mass, and volume scores. The largest BA limits were observed for volume scores (-1552.8 to 574.2), which was massively improved (-241.0 to 300.4, COV 11.5%) after reanalysing the 64-DSCT scans (Siemens) with GE software/workstation (while Siemens software/workstation does not allow cross-vendor analysis). Phantom measurements confirmed overestimation of volume scores by 'syngo Ca-Scoring' (Siemens) software which should therefore be reviewed (vendor has been notified).
Intra- and inter-scan agreement of CAC measurement in a given data set is excellent. Inter-scanner variability is reasonable, particularly for Agatston units in the clinically most relevant range <1000. The use of different software solutions has a greater influence particularly on volume scores than the use of different scanner types.
冠状动脉钙化（CAC）评分已成为一种用于风险分层的工具，并且可能用于监测危险因素改变的反应。因此，重复测量应该提供可靠的结果和低的扫描仪间变异性，以允许有意义的比较。本研究的目的是通过对头对头比较使用两种不同的心脏 CT 扫描仪：64 层多排螺旋 CT（MSCT）和 64 层双源 CT（DSCT），来研究 CAC 评分的 Agatston、体积和质量评分的扫描仪间变异性。
30 例患者在<100 天内（0-97 天）在 64-MSCT（GE LightSpeed XT 扫描仪：120 kV，70 mAs，2.5mm 切片）和 64-DSCT（西门子 Somatom Definition：120 kV，80 mAs，3mm 切片）上进行 CAC 测量。回顾性扫描内比较显示出极好的相关性。所有 CAC 评分的狭窄一致性界限和变异系数（COV）为 r≥0.99（P<0.001），证明了极好的扫描内（观察者间）一致性，并且对于两种扫描仪（64-MSCT/64-DSCT），COV 均较低，即 Agatston（2.0/2.1%）、质量（3.0/2.0%）和体积（4.7/3.9%）。尽管所有评分的相关性均很高（r≥0.97），但扫描仪间比较显示出更大的 Bland-Altman（BA）一致性界限，Agatston、质量和体积评分的 COV 分别为 15.1%、21.6%和 44.9%。体积评分的 BA 界限最大（-1552.8 至 574.2），在重新分析 64-DSCT 扫描（西门子）并使用 GE 软件/工作站（而西门子软件/工作站不允许交叉供应商分析）后，BA 界限大大改善（-241.0 至 300.4，COV 为 11.5%）。体模测量证实“syngo Ca-Scoring”（西门子）软件对体积评分的高估，因此应进行审查（已通知供应商）。
在给定数据集内 CAC 测量的扫描内和扫描间一致性非常好。扫描仪间的变异性是合理的，特别是在临床最相关的<1000 范围内的 Agatston 单位。使用不同的软件解决方案比使用不同的扫描仪类型对体积评分的影响更大。
