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.

Abstract

Objective: 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).

Material and methods: 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.

Results: Correlation between CAC scores obtained using low current-low kVp protocol and standard protocol in derivation cohort was excellent (r = 0.99; p < 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; p < 0.0001).

Conclusion: 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.