Multimodality Assessment of Ascending Aortic Diameters: Comparison of Different Measurement Methods Jos e F. Rodr  ıguez-Palomares, MD, PhD, Gisela Teixid o-Tura, MD, PhD, Valentina Galuppo, MD, Hug Cu ellar, MD, Ana Laynez, MD, Laura Guti errez, MD, Mar  ıa Teresa Gonz alez-Alujas, MD, PhD, David Garc  ıa-Dorado, MD, PhD, and Arturo Evangelista, MD, PhD, Barcelona, Spain Background: Transthoracic echocardiography (TTE), multidetector computed tomography (MDCT), and mag- netic resonance imaging (MRI) have been widely used to monitor aortic diameters, with no consensus as to the best measurement approach. Thus, the aim of this study was to establish the best measurement methods by two-dimensional (2D) TTE, MDCT, and MRI to achieve comparable aortic diameters. Methods: One hundred forty patients with severe aortic valvular disease or aortic dilatation were prospectively evaluated using 2D TTE and MDCT (n = 70) or MRI (n = 70). The aorta was measured at three different levels: sinuses of Valsalva, sinotubular junction, and ascending aorta. Three different measurements were made by 2D TTE—inner edge to inner edge, leading edge to leading edge (L-L), and outer edge to outer edge—and then compared with the inner edge–to–inner edge and outer edge–to–outer edge measurements of cusp-to-cusp and cusp-to-commissure diameters by MDCT or MRI. Inter- and intraobserver variability was analyzed. Results: Aortic diameters by 2D TTE, MDCT, and MRI showed excellent inter- and intraobserver variability using all conventions. Significant underestimation was observed of all aortic diameters assessed by 2D TTE using the inner edge–to–inner edge convention compared with those obtained by MDCT or MRI (P < .0001). However, excellent accuracy was observed by 2D TTE when the L-L convention was used and compared with the internal diameter by MDCT and MRI (mean differences, 0.6 6 2.6 mm [P = .158] for MDCT and 0.4 6 3.5 mm [P = .852] for MRI). Cusp-to-cusp diameters were slightly larger than cusp-to- commissure diameters. The diameter by 2D TTE using the L-L convention correlated best with the noncoro- nary cusp–to–right coronary cusp diameter determined by both MDCT and MRI. Conclusions: Aortic root and ascending aortic diameters measured by 2D TTE using the L-L convention showed accurate and reproducible values compared with internal diameters assessed by MDCT or MRI. This approach permits a multimodality follow-up of patients with aortic diseases and avoids disparities in measurements obtained by different conventions. (J Am Soc Echocardiogr 2016;-:---.) Keywords: Aortic root, Ascending aorta, Computed tomography, Cardiac magnetic resonance, Transthoracic echocardiography Ascending aortic aneurysm is a major cause of morbidity and mortal- ity, 1,2 including aortic dissection, aortic rupture, and heart failure secondary to aortic regurgitation. Accurate measurement of aortic diameter plays a pivotal role in the diagnosis, follow-up, and manage- ment of ascending aortic dilatation. Two-dimensional (2D) transthoracic echocardiography (TTE), contrast-enhanced multidetector computed tomography (MDCT), and magnetic resonance imaging (MRI) are the most used imaging techniques in the clinical management of ascending aortic diseases. 3-5 Because of its widespread availability, 2D TTE is the technique of choice for measuring proximal aortic segments in clinical practice. Standard measurement conventions established the leading edge–to–leading edge (L-L) diameter in end-diastole, and most of the epidemiologic and clinical data published to date were obtained using this methodology. 6 However, the American College of Cardiology and American Heart Association (AHA) guidelines, in an attempt to increase intertechnique reproducibility and agreement, proposed measuring aortic diameter using the inner edge–to–inner edge (I-I) method by 2D TTE 4 and the external diameter (outer edge–to–outer edge [O-O]) perpendicular to the axis of blood flow by MDCT or MRI. Reference values using the I-I method by 2D TTE in a large adult population have been published. 7 The recently published American From the Department of Cardiology (J.F.R.-P., G.T.-T., V.G., A.L., L.G., M.T.G.-A., D.G.-D., A.E.) and the Department of Radiology (H.C.), Hospital Universitari Vall d’Hebron, Barcelona, Spain; and Institut de Recerca (VHIR), Universitat Aut onoma de Barcelona, Barcelona, Spain (J.F.R.-P., G.T.-T., V.G., A.L., L.G., M.T.G.-A., D.G.-D., A.E.). This study was supported by a grant from Red de Investigaci  on Cooperativa de las Enfermedades Cardiovasculares of the Instituto de Salud Carlos III, Ministerio de Sanidad y Consumo, Spain. Reprint requests: Arturo Evangelista, MD, PhD, Department of Cardiology, Hospi- tal Universitari Vall d’Hebron, Paseo Vall d’Hebron 119-129, 08035, Barcelona, Spain (E-mail: aevangel@vhebron.net). 0894-7317/$36.00 Copyright 2016 by the American Society of Echocardiography. http://dx.doi.org/10.1016/j.echo.2016.04.006 1