Evaluation of reliability and radiation dose reduction in coronary artery calcium scoring by using a low tube current and low kilo-voltage peak with advanced modelled iterative reconstruction

The present study sought to compare the reliability and radiation dose of coronary artery calcium (CAC) scoring using low tube current (16 mAs), low kilo-voltage peak (100 kVp) and advanced modelled iterative reconstruction (ADMIRE 5) with the standard protocol (80 mAs, 120 kVp, ADMIRE 3). A prospective single centre study including 200 consecutive patients with suspected coronary artery disease referred for CT coronary angiography was conducted. All 200 patients underwent CAC scoring using the low current-low kVp protocol as well as standard protocol and were subdivided into a derivation and validation cohorts. Correlation between CAC scores obtained using low current-low kVp protocol and standard protocol in derivation cohort was excellent (<i>r</i> = 0.99; <i>p</i> &lt; 0.001). A linear regression model was used to derive a formula for predicting CAC that enabled conversion of CAC(low current-low kVp) to CAC(corrected) [CAC(corrected) = 1.067 × CAC(low current-low kVp)]. The formula was applied in validation cohort where CAC (corrected) showed excellent agreement with CAC(standard) (intraclass correlation coefficient, 0.9970; 95%CI, 0.9956–0.9980). Excellent agreement for risk classification (weighted kappa, 0.94379; 95%CI, 0.89629–0.99130) was observed between CAC(corrected) and CAC(standard) scores. The low current-low kVp protocol demonstrated an 88.87% reduction in radiation dose (0.0679 ± 0.01032 mSv vs. 0.610 ± 0.2403 mSv; <i>p</i> &lt; 0.0001). The low current-low kVp protocol for CAC scoring has comparable reliability to the standard technique with significant radiation dose reduction. This extremely low-dose protocol may prove useful as an alternative to standard CAC scoring, particularly for screening in the low-to-intermediate risk population.