Aortic Measurements in Patients with Aortopathy are Larger and More Reproducible by Cardiac Magnetic Resonance Compared with Echocardiography.

Accurate and reproducible aortic measurements are essential in aortopathy patients. Transthoracic echocardiography (TTE) is commonly used but has several limitations. Cardiac magnetic resonance (CMR) can offset these limitations but has not been directly compared with TTE. We compared the reproducibility of CMR and TTE measurements at multiple aortic levels. Patients with a connective tissue disorder (CTD) or bicommissural aortic valve (BAV) (n = 41; 22 CTD, 19 BAV; mean age 18.8 ± 8.9 years) with TTE and CMR imaging performed within 3 months of each other were randomly selected. Two blinded observers measured the aorta at multiple anatomic levels. Intra- and interobserver variability and agreement between techniques were assessed. Aortic root diameter measurements by TTE and CMR were equally reproducible (% error 4-10 %), but TTE measurements were systematically smaller by 5-7 % (p < 0.0001). Systematic differences were larger in BAV (11-12 %, p < 0.0001) due to root asymmetry. CMR measurements of aortic root cross-sectional area were feasible and highly reproducible (% error 5-8 %). Compared with CMR, ascending aorta measurements by TTE were less reproducible, especially in BAV (% error 21-24 vs. 6-7 %, p = 0.01). Distal aortic measurements by TTE were 14-29 % smaller and had poor reproducibility compared with CMR (% error 24-42 vs. 9-10 %; p < 0.0001). CMR measurement of the largest aortic root dimension is more reliable than TTE, especially when the root is asymmetric. Measurements of the thoracic aorta distal to the root by CMR are more accurate and reproducible than by TTE. These data support a role for CMR in aortopathy patients.