The Added Value of a Dedicated Cardiac CT Scanner for the Assessment of Coronary Calcium

Abstract

The amount of coronary calcium is generally used as an indicator for risk stratification of patients with (suspected) coronary artery disease. Orginally, electron beam tomography (EBT) was used to image the amount of coronary calcium and quantification was performed by the Agatston score. Risk stratification has been validated on large patients populations using the EBT scanner in combination with this scoring method. While EBT scanners become more and more obsolete nowadays, these scanners are being replaced by multi-detector computer tomography (MDCT) systems and dedicated cardio scanners like dual source computer tomography (DSCT). However, in order to used the calcium score obtained from a patient scan on these systems, it must be demonstrated to be accurate, clinically relevant and reproducible. In this study we compared the infiuence of cardiac motion on the calcium score for a 64-slice MDCT scanner and for an EBT and a DSCT systems. A moving cardiac phantom was used and the measured Agatston scores were compared on these three systems as a function of heart rate, calcification density and slice thickness. The results show that DSCT is approximately 50% less susceptible to cardiac motion than 64-slice MDCT and that the susceptibility is further reduced by using a smaller slice thickness. At a slice thickness of 3.0 mm DSCT and 64-slice MDCT show similar results, however, at a slice thickness of 0.6 mm DSCT gives the best approximation of the calcium score on EBT in comparison to 64-slice MDCT.