QUANTIFYING AORTIC VALVE CALCIFICATION FROM A CONTRAST-ENHANCED CARDIAC COMPUTED-TOMOGRAPHY ANGIOGRAPHY STUDY

Abstract

Background: Aortic valve calcification (AVC) has been associated with major adverse cardiovascular events and severity of aortic stenosis. Quantification of AVC has been previously performed using non-contrast enhanced ECG-gated CT. With the adoption of transcutaneous aortic valve implantation (TAVI), pre-TAVI contrast enhanced ECG-gated CT are being commonly performed to determine valve sizing. We sought to develop and validate a method to quantify AVC using cardiac CT angiography (CCTA). Methods: Patients who underwent both AVCStandard and CCTA scans were identified. AVCStandard images were scored using the Agatston method. A derivation cohort of 25 patients was identified and analysed. An additional 34 patients were identified for the validation cohort. AVCCCTA scans were scored for AVC (AVCCCTA), whereby AVC was defined as plaque with attenuation 2 SD above the mean attenuation value of the ascending aorta (HUaorta). The correlation between AVCStandard and AVCCCTA was determined with the slope used to derive a correction factor for the conversion of AVCCCTA results to a AVCStandard Agatston score (AS). To test applicability, the correction factor was assessed in a separate validation cohort. Results: In the derivation cohort, the correlation between AVCStandard and AVCCCTA was excellent (r =0.942). The slope (y = 1.824 × AVCCCTA score) measured in the derivation cohort was used to adjust AVCCCTA measured in the validation cohort. There was excellent correlation (r=0.942) and agreement (kappa = 0.918) between AVCCCTA corrected and AVCStandard. Conclusion: Quantification of AVC from a single contrast-enhanced CCTA scan is feasible and correlates well with AVCStandard. Larger, multicentre studies are needed to validate the universal applicability of AVC quantified using CCTA.