Comparison of dual-source and electron-beam CT for the assessment of coronary artery calcium scoring

Objective

Cardiac CT allows the detection and quantification of coronary artery calcification (CAC). Electron-beam CT (EBCT) has been widely replaced by high-end CT generations in the assessment of CAC. The aim of this study was to compare the CAC scores derived from an EBCT with those from a dual-source CT (DSCT).

Methods

We retrospectively selected 92 patients (61 males; mean age, 60.7±12 years) from our database, who underwent both EBCT and DSCT. CAC was assessed using the Agatston score by two independent readers (replicates: 1, 2; 3=mean of reading 1 and 2).

Results

EBCT scores were on average slightly higher than DSCT scores (281±569 vs 241±502; p<0.05). In regression analysis R²-values vary from 0.956 (1) to 0.966 (3). We calculated a correction factor as EBCT=(DSCT+1)^1.026–1. When stratifying into CAC categories (0, 1–99, 100–399, 400–999 and ≥1000), 79 (86%) were correctly classified. From those with positive CAC scores, 7 out of 61 cases (11%, κ=0.81) were classified in different categories. Using the corrected DSCT CAC score, linear regression analysis for the comparison to the EBCT results were r=0.971 (p<0.001), with a mean difference of 6.4±147.8. Five subjects (5.4%) were still classified in different categories (κ=0.84).

Conclusion

CAC obtained from DSCT is highly correlated with the EBCT measures. Using the calculated correction factor, agreement only marginally improved the clinical interpretation of results. Overall, for clinical purposes, face value use of DSCT-derived values appears as useful as EBCT for CAC scoring.Cardiac CT allows the detection and quantification of coronary artery calcification (CAC) and may thus add important in vivo information on the path from risk factor exposure to formation of clinical events 1-4]. Because of its advantages of being a fast technique with limited radiation exposure to the patients, various published clinical outcome data from CAC are based on electron-beam CT (EBCT), and therefore cut-points have been established for EBCT scans. However, since the appearance of newer generations of CT scanners such as dual-source CT (DSCT), scanners of this type are also widely used for CAC scoring as an alternative to EBCT. The spatial resolution of DSCT scanners is much higher, enabling the detection of smaller lesions, and DSCT is more applicable to other radiological procedures such as CT angiography 5]. CAC scoring is performed on these newer scanner generations using the Agatston score algorithm as the standard measure of CAC quantification. There is direct comparison of CAC scores between newer scanners and EBCT 6-9]. However, comparison between EBCT and DSCT is rare 10]. This is of interest for first-time CAC scoring in asymptomatic subjects, and especially for evaluation of disease progression in subjects with prior EBCT testing. Therefore, the aim of this study was to evaluate the diagnostic accuracy of DSCT in the detection of CAC scores to EBCT. In addition, we compared techniques with each other, verifying the ability of CAC score classification.