Aortic stenosis: Comparative evaluation of 16-detector row CT and echocardiography

Purpose: To prospectively evaluate whether planimetric measurements of aortic valve area (AVA) with 16-detector row computed tomography (CT) allow classification of aortic stenosis (AS). Materials and Methods: The study had institutional review board approval; patients gave informed consent. Twenty patients (11 men, nine women; mean age, 63 years) with AS and 20 patients (10 men, 10 women; mean age, 65 years) without underwent transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), and retrospectively electrocardiographically gated 16-detector row CT. Twenty CT data sets were reconstructed in 5% steps of R-R interval; data analysis was performed with four-dimensional software. Maximum AVA in systole planimetrically measured with CT (AVA(CT)) was compared with AVA planimetrically measured with TEE (AVA(TEE)), AVA calculated with the continuity equation and TTE (AVA(TTE)), and transvalvular pressure gradients determined with the Bernoulli equation and TTE. Correlations among AVA(CT), AVA(TTE), AVA(TEE), and transvalvular pressure gradients were tested with bi-variate regression analysis; agreement between methods was assessed with the Bland-Altman method. Results: In patients without AS, mean AVA(CT) was 3.56 cm(2) +/- 0.66 and mean AVA(TEE) was 3.43 cm(2) +/- 0.69. In patients with AS, mean AVA(CT) was 0.89 cm(2) +/- 0.35; mean AVA(TEE), 0.86 cm(2) +/- 0.35; and mean AVA(TTE), 0.83 cm(2) +/- 0.33. Mean transvalvular pressure gradient was 51 mm Hg +/- 22. Significant correlations were present between AVA(CT) and AVA(TEE) (r = 0.99, P < .001), AVA(CT) and AVA(TTE) (r = 0.95, P < .001), and AVA(CT) and transvalvular pressure gradients (r = -0.74, P < .01). Mean differences were -0.08 cm(2) (limits of agreement: -0.32, 0.16) for AVA(CT) versus AVA(TEE) and 0.06 cm(2) (limits of agreement: -0.15, 0.26) for AVA(CT) versus AVA(TTE). Conclusion: Planimetric measurements of AVA with retrospectively electrocardiographically gated 16-detector row CT allow classification of AS that is similar to that achieved with measurements by using echocardiographic methods.