What is the best Computed Tomography (CT) scan to screen for an ascending aortic aneurysm?

From the Guidelines

The best CT scan to screen for an ascending aorta aneurysm is a cardiac-gated contrast-enhanced CT angiography (CTA) of the chest, as recommended by the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1. This imaging modality provides excellent visualization of the aorta and can accurately measure the diameter of the ascending aorta to detect aneurysms. The use of cardiac-gated CT is crucial in reducing motion artifacts from cardiac pulsation, which is particularly important for the ascending aorta due to its proximity to the heart.

The protocol typically involves administration of intravenous iodinated contrast material (usually 80-120 mL depending on patient weight) followed by scanning during the arterial phase.

• The images should be reconstructed in multiple planes (axial, sagittal, and coronal) with thin slices (1-1.5 mm) to allow for precise measurements and 3D reconstructions.
• For patients with renal impairment, a non-contrast CT can be performed, though it provides less detailed information.
• Radiation dose should be minimized using dose modulation techniques, particularly for younger patients who may need repeated surveillance imaging, as emphasized in the 2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients with thoracic aortic disease 1.
• The choice between CT or MRI depends on patient characteristics, institutional expertise, renal function, affordability, and radiation exposure concerns, as noted in the 2022 ACC/AHA guideline 1.
• The 2014 ESC guidelines on the diagnosis and treatment of aortic diseases also recommend the use of ECG-gated acquisition protocols and high-end MSCT scanners for imaging the aorta 1.

This imaging approach is preferred because it offers superior spatial resolution compared to MRI and is more widely available, faster, and less expensive than MRI while providing comprehensive evaluation of the entire aorta and adjacent structures.

From the Research

Computed Tomography (CT) Scan for Ascending Aortic Aneurysm

• The best CT scan to screen for an ascending aortic aneurysm is ECG-gated computerized tomographic angiography 2, 3.
• This type of CT scan allows for precise diameter assessment and accurate preoperative planning, and can help avoid movement artifacts and provide a more precise definition of proximal aortic segments (aortic arch, ascending aorta) 3.
• Inner-to-inner "cusp to cusp" diameter measured on an ECG-gated CT should be used for comparison with 2D TTE aortic diameter at the level of the sinuses of Valsalva in patients with thoracic aortic aneurysms 2.
• Cardiac computed tomography angiography (CTA) is also an excellent imaging modality for diagnosing thoracic aortic aneurysm (TAA) and allows simultaneous analysis of the coronary artery tree 4.

Key Considerations

• The gold standard for aneurysm evaluation is computed tomography angiography (CTA) 3.
• CT scan and echocardiography are the main exams in the evaluation of the diameter of the ascending aorta and its follow up 5.
• Contrast CT scan, echocardiography, angiography, and MRI are the most useful diagnostic procedures for postoperative pseudoaneurysms of the ascending aorta 6.