Quantifying Aortic Valve Calcification using Coronary Computed Tomography Angiography

Abstract

Introduction Aortic valve calcification (AVC) has been associated with major adverse cardiovascular events and all-cause mortality. We sought to develop and validate a method to quantify AVC using coronary CT angiography (CTA). Methods Of 59 patients who underwent both non-contrast and contrast enhanced coronary CTA, 25 patients served as the derivation cohort and 34 patients served as the validation cohort. For non-contrast enhanced CT, quantification of AVC was performed using the Agatston method for coronary artery calcification (CAC). For contrast enhanced coronary CTA, a region of interest (ROI) was placed in the ascending aorta and the mean aortic attenuation value (HUAorta) and standard deviation (SD) were measured. Using a calcium threshold of mean HUAorta + 2SD, the AVCCTA was calculated. All other Agatston score parameters (weighting factors and area calculations) remained unchanged. Results In the derivation cohort, the correlation between AVCCAC and AVCCTA was excellent (r = 0.982). Using the line of best fit, a correction factor was calculated enabling the conversion of AVCCTA results to a AVCCAC equivalent (AVCCorrected = 1.868 × AVCCTA). Using this correction in the validation cohort, the correlation and agreement between AVCCAC and AVCCorrected were good (ICC = 0.939; 95% CI: 0.881–0.969; kappa = 0.700; 95% CI: 0.469–0.931). Conclusion The quantification of AVCCorrected using contrast enhanced CTA is feasible using a systematic approach with very good reliability and good agreement with AVCCAC. Larger-scale validation studies are needed to determine whether the use of AVCCAC can be eliminated in favour of AVCCorrected.