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Jelena R. Ghadri, Robert Goetti, Michael Fiechter, Aju P. Pazhenkottil, Silke M. Küest, Rene N. Nkoulou, Christina Windler, Ronny R. Buechel, Bernhard A. Herzog, Oliver Gaemperli, Christian Templin, Philipp A. Kaufmann, Inter-scan variability of coronary artery calcium scoring assessed on 64-multidetector computed tomography vs. dual-source computed tomography: a head-to-head comparison, European Heart Journal, Volume 32, Issue 15, August 2011, Pages 1865–1874, https://doi.org/10.1093/eurheartj/ehr157
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Abstract
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.
