Otani K, Takeuchi M, Kaku K, Sugeng L, Yoshitani H, Haruki N, Ota T, Mor-Avi V, Lang RM, Otsuji Y. Assessment of the aortic root using real-time 3D transesophageal echocardiography. Circ J. 2010 Nov; 74(12):2649-57.