Agreement of Proximal Thoracic Aorta Size by Two-Dimensional Transthoracic Echocardiography and Magnetic Resonance Angiography

There is currently a lack of uniformity in methods of aortic diameter measurements across different imaging modalities. In this study, we sought to evaluate the accuracy of transthoracic echocardiography (TTE) in comparison with magnetic resonance angiography (MRA) for the measurement of proximal thoracic aorta diameters. This is a retrospective analysis of 121 adult patients at our institution who had TTE and electrocardiogram (ECG)-gated MRA performed within 90 days of each other between 2013 and 2020. Measurements were made at the level of sinuses of Valsalva (SoV), sinotubular junction (STJ), and ascending aorta (AA) using leading edge–to–leading edge (LE) convention for TTE and inner-edge–to–inner-edge (IE) convention for MRA. Agreement was assessed using Bland-Altman methods. Intra- and interobserver variability were assessed by intraclass correlation. The average age of patients in the cohort was 62 years, and 69% of patients were male. The prevalence of hypertension, obstructive coronary artery disease, and diabetes was 66%, 20%, and 11%, respectively. The mean aortic diameter by TTE was SoV 3.8 ± 0.5 cm, STJ 3.5 ± 0.4 cm, and AA 4.1 ± 0.6 cm. The TTE-derived measurements were larger than the MRA ones by 0.2 ± 2 mm, 0.8 ± 2 mm, and 0.4 ± 3 mm at the level of SoV, STJ, and AA, respectively, but the differences were not statistically significant. There were no significant differences in the aorta measurements by TTE compared with MRA, when stratified by gender. In conclusion, transthoracic echocardiogram-derived proximal aorta measurements are comparable to MRA measurements. Our study validates current recommendations that TTE is an acceptable modality for screening and serial imaging of the proximal aorta.