Vendor-independent Aortic Valve Calcium Scoring in Patients with Discordant Echocardiographic Criteria of Severe Aortic Stenosis

Purpose To apply a vendor-neutral Agatston score (vnAS) for aortic valve calcification across multiple CT systems and to aortic stenosis severity classification. Materials and Methods Anthropomorphic phantoms with varying degrees of calcification were scanned using seven different CT systems and a reference electron-beam CT system to determine the vnAS. The vnAS was calculated using a regression model, whose performance was evaluated by both the coefficient of determination and analysis of variance. The vnAS was subsequently validated on a retrospective patient sample from eight international centers. Thresholds of severe aortic valve stenosis were defined as 1274 and 2065 AU for women and men, respectively. Results The Agatston scores from all CT systems were strongly correlated with that of the reference system (R2 > 0.932). On the basis of their echocardiographic findings, 183 of 831 (22.0%) patients (mean age ± SD, 77 years ± 10; 351 of 831 [42.2%] women) had discordant echocardiographic aortic valve stenosis findings. Among women with discordant results, the vnAS was higher than the traditional aortic valve calcium score (median, 1693 AU [IQR, 908-2513 AU] vs 1181 AU [IQR, 726-1964 AU], respectively; P < .001). Similar findings were observed for men (median, 2658 AU [IQR, 1894-3822 AU] vs 2056 AU [IQR, 1408-3056 AU], respectively; P < .001). Using the vnAS, 8.5% of women and 17.8% of men with discordant echocardiographic findings were reclassified into the severe aortic stenosis group. Conclusion A previously developed calibration tool, the vnAS, was validated and reclassified patients with discordant echocardiographic findings into the severe aortic stenosis group. Keywords: CT, Echocardiography, Percutaneous, Cardiac, Valves, Calcifications/Calculi, Technology Assessment, Vendor-neutral Agatston Score, Aortic Stenosis, Aortic Valve Calcification, Phantoms Supplemental material is available for this article. © RSNA, 2026 See also commentary by Jaltotage and Leipsic in this issue.