Impact of motion artefact on the measurement of coronary calcium score

Reports have shown that total coronary calcium (CC) measured by electron be am CT (EBCT) correlates well with atheroma extent, and this in turn is a re liable indicator of risk for future ischaemic events. Although total CC may be measured using a conventional CT scanner, image quality is degraded by cardiac motion artefact. Errors in CC measurement owing to slice misregistr ation between adjacent breath-holds affect both conventional CT and EBCT. T he latest generation conventional CT scanners have acquisition times of 500 ms or shorter, and, when combined with ECG triggering, quantitative CC mea surement without reliance upon EBCT becomes a real possibility. We investig ated the effect of motion on the measured calcium score using a moving phan tom. Our results show that use of ECG triggering with conventional CT impro ves reproducibility of Agatston calcium score measurement. Increasing motio n time during image acquisition results in an apparent increase in the Agat ston CC score. Alternative measures of the amount of CC may be less suscept ible to motion-induced bias, but have a similar reproducibility.