Quantifying Aortic Valve Calcification Using Coronary Computed Tomography Angiography

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 (HU) and standard deviation (SD) were measured. Using a calcium threshold of mean HU + 2SD, the AVC was calculated. All other Agatston score parameters (weighting factors and area calculations) remained unchanged.

Results: In the derivation cohort, the correlation between AVC and AVC was excellent (r = 0.982). Using the line of best fit, a correction factor was calculated enabling the conversion of AVC results to a AVC equivalent (AVC = 1.868 × AVC). Using this correction in the validation cohort, the correlation and agreement between AVC and AVC were good (ICC = 0.939; 95% CI: 0.881-0.969; kappa = 0.700; 95% CI: 0.469-0.931).

Conclusion: The quantification of AVC using contrast enhanced CTA is feasible using a systematic approach with very good reliability and good agreement with AVC. Larger-scale validation studies are needed to determine whether the use of AVC can be eliminated in favour of AVC.