Abstract
AimsTo investigate the value of coronary calcium scoring (CCS) as a filter scan prior to coronary computed tomography angiography (CCTA).Methods and ResultsBetween February 2008 and April 2011, 732 consecutive patients underwent clinically indicated CCTA. During this ‘control phase’, CCS was performed in all patients. In patients with CCS≥800, CCTA was not performed. During a subsequent ‘CCTA phase’ (May 2011–May 2012) another 200 consecutive patients underwent CCTA, and CCS was performed only in patients with increased probability for severe calcification according to age, gender and atherogenic risk factors. In patients where CCS was not performed, calcium scoring was performed in contrast-enhanced CCTA images. Significant associations were noted between CCS and age (r = 0.30, p<0.001) and coronary risk factors (χ2 = 37.9; HR = 2.2; 95%CI = 1.7–2.9, p<0.001). Based on these associations, a ≤3% pre-test probability for CCS≥800 was observed for males <61 yrs. and females <79 yrs. According to these criteria, CCS was not performed in 106 of 200 (53%) patients during the ‘CCTA phase’, including 47 (42%) males and 59 (67%) females. This resulted in absolute radiation saving of ∼1 mSv in 75% of patients younger than 60 yrs. Of 106 patients where CCS was not performed, estimated calcium scoring was indeed <800 in 101 (95%) cases. Non-diagnostic image quality due to calcification was similar between the ‘control phase’ and the ‘CCTA’ group (0.25% versus 0.40%, p = NS).ConclusionThe value of CCS as a filter for identification of a high calcium score is limited in younger patients with intermediate risk profile. Omitting CCS in such patients can contribute to further dose reduction with cardiac CT studies.
Highlights
Recent technical developments with coronary computed tomography angiography (CCTA) constituted an important step forward for the non-invasive diagnostic work-up of symptomatic patients with suspected or known coronary artery disease (CAD) [1]
Calcium Scoring (CCS) was performed in all patients of our ‘control phase’ and in a selected group of patients in our ‘CCTA cohort’ using the following imaging parameters: tube voltage of 120 kV with an effective tube current-time product of 55 mAs per section, slice collimation 3260.625-mm acquisition and a 0.33 s gantry rotation time
Using receiver operating characteristics (ROC) analysis, we found that age and atherogenic risk factors are predictive of CCS$800 (AUCage = 0.77, AUCrisk factors = 0.65)
Summary
Recent technical developments with coronary computed tomography angiography (CCTA) constituted an important step forward for the non-invasive diagnostic work-up of symptomatic patients with suspected or known coronary artery disease (CAD) [1]. With current dose reduction strategies (dose modulation, prospective ECG-gating, low-tube voltage imaging and iterative reconstruction algorithms) the radiation exposure for CCTA can be substantially reduced, so that the relative dose for CCS may equal or even be higher than that required for CCTA [8,9,10]. From this point of view, and in light of the limited prognostic and diagnostic value of CCS in symptomatic patients [11,12,13], its usefulness as a filter scan prior to CCTA needs to be reconsidered
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