Multimodality Noninvasive Imaging of Thoracic Aortic Aneurysms: Time to Standardize?

Aortic imaging is an essential part of a surveillance program for patients with a confirmed or suspected aortopathy because aortic size is crucial for predicting the risk of death, aortic rupture, or aortic dissection. Noninvasive aortic imaging relies on transthoracic and transesophageal echocardiography, cardiovascular magnetic resonance and computed tomography (CT) imaging. Echocardiography and cardiovascular magnetic resonance offer comprehensive anatomical and functional evaluation of the heart, aortic valve, and aorta, and CT is more limited to anatomical data. However, CT is fast, available, and less operator-dependent. There is general consensus that the aorta should be measured at reproducible anatomical landmarks on electrocardiogram-gated images, perpendicular to the blood flow and using multiplanar reconstruction if possible. The method of measurement must be included in the clinical report. Normal aortic size depends on age, sex, and body size. Serial measurements should use identical methods. There is controversy about the inclusion of the aortic wall in the vessel diameter and the trigger time in the cardiac cycle for measurement, although diastole is more reproducible. The best method to measure the diameter of the sinuses of Valsalva remains unclear. Imagers and clinicians should pay close attention to the aorta measurement techniques and weigh the clinical implications of modification of their institutional protocols.