Accuracy of Matrix-Array Three-Dimensional Echocardiographic Measurements of Aortic Root Dilation and Comparison with Two-Dimensional Echocardiography in Pediatric Patients

Background: Cardiac magnetic resonance imaging has demonstrated that the aortic root may be dilated in a dimension that two-dimensional echocardiography (2DE) is not able to interrogate. In the standard parasternal long-axis view, only a portion of the aortic root in the anteroposterior (AP) dimension can be visualized, as opposed to three-dimensional (3D) echocardiography (3DE), which can capture the entire root in an infinite number of planes. The purposes of the present study were to compare measurements of dilated aortic roots between 3DE and 2DE and to evaluate interobserver variability on 3DE. Methods: Thirty-one patients (median age, 13 years) with aortic root dilation were identified. Two-dimensional echocardiographic images and full-volume electrocardiographically gated 3D echocardiographic (3DE) images were obtained. Two blinded observers measured six dimensions of the aortic root in the short-axis view: three in the AP dimension and three in the transverse dimensions. Two-dimensional echocardiographic measurements were made by a third blinded observer. The largest AP 3DE measurement was compared with two-dimensional echocardiographic measurements. Interobserver 3DE measurements were also compared. Results: The median aortic root Z score was +2.63. Maximum 3DE measurement in any plane of the root size was significantly greater than on 2DE (P < .0001). The largest AP dimension by 3DE was significantly greater than on 2DE (P = .001). There was no significant interobserver variability for the largest dimension or those in the AP dimension, but a difference was found in the transverse dimension (P = .02). Conclusions: Three-dimensional echocardiography compares favorably with 2DE in the evaluation of aortic root dilation in patients with known histories of aortic root disease. Three-dimensional echocardiography found that the largest diameter measured was significantly larger than on 2DE. The interobserver variability of 3DE is low, particularly in the AP dimension and in identifying the largest diameter. Three-dimensional echocardiography can be a useful technique in the periodic surveillance of patients with aortic root dilation. (J Am Soc Echocardiogr 2012;25:287-93.)