What computed tomography (CT) scan is needed for a tortuous aorta?

From the Guidelines

For a tortuous aorta, a contrast-enhanced CT angiography (CTA) of the chest and abdomen is the recommended imaging study. This specialized CT scan uses intravenous contrast material to clearly visualize the entire aorta and its branches, allowing for detailed assessment of the vessel's tortuosity, diameter, and any associated complications. The scan should be performed with ECG-gating when possible to minimize motion artifacts from cardiac pulsation, particularly when evaluating the ascending aorta and aortic arch. Typically, a non-contrast scan is obtained first, followed by the contrast-enhanced images. The radiologist should use thin-slice (1-2mm) multiplanar reconstructions and 3D volume rendering techniques to fully characterize the tortuous segments. Patients should fast for 4-6 hours before the procedure but continue to drink clear fluids to maintain hydration. Those with impaired kidney function may require special preparation with pre-hydration or alternative contrast agents, as standard iodinated contrast can potentially cause kidney injury in at-risk individuals. CTA is preferred over MRA (magnetic resonance angiography) for tortuous aorta evaluation due to its superior spatial resolution, faster acquisition time, and ability to detect calcifications, which are often associated with tortuous vessels, as supported by recent studies 1.

Some key points to consider when performing a CTA for a tortuous aorta include:

• The use of ECG-gating to minimize motion artifacts
• The acquisition of non-contrast and contrast-enhanced images
• The use of thin-slice multiplanar reconstructions and 3D volume rendering techniques
• The need for special preparation in patients with impaired kidney function
• The preference for CTA over MRA due to its superior spatial resolution and ability to detect calcifications, as noted in studies such as 1 and 1.

Overall, a contrast-enhanced CTA of the chest and abdomen is the most appropriate imaging study for evaluating a tortuous aorta, as it provides detailed information about the vessel's anatomy and any associated complications, and is supported by recent evidence 1.

From the Research

CT Scan for Tortuous Aorta

To determine the appropriate CT scan for a tortuous aorta, several factors must be considered, including the type of contrast agent used and the imaging technique employed.

• Contrast Agents: Studies have compared the effectiveness of different contrast agents in vascular imaging, including iodixanol and iohexol 2. Iodixanol, a dimeric nonionic iso-osmolar contrast agent, has been shown to provide equal vascular enhancement compared to iohexol, a monomeric nonionic hyperosmolar contrast agent, despite having a lower iodine concentration.
• Imaging Techniques: Contrast-enhanced CT angiography is currently considered the gold standard for preoperative imaging and image-based treatment planning in abdominal aortic aneurysm repair 3. This technique provides accurate assessment of the maximum aortic diameter and allows for precise determination of aortic diameters.
• Low-Dose Contrast CT: Research has also explored the use of low-dose contrast CT protocols for transcatheter aortic valve replacement assessment, utilizing monoenergetic 40 keV reconstruction and dual-layer CT scanners 4. This approach has been shown to provide better contrast/signal to noise ratio and increased soft tissue contrast, permitting better delineation of contrast-filled structures at lower doses of iodinated contrast media.
• CT Scan Types: While the studies do not specifically address the type of CT scan needed for a tortuous aorta, they suggest that contrast-enhanced CT angiography is a suitable imaging technique for evaluating vascular diseases, including abdominal aortic aneurysms 5, 6.

Key Findings

• Iodixanol and iohexol have similar enhancement characteristics in vascular imaging 5, 2.
• Contrast-enhanced CT angiography is the gold standard for preoperative imaging in abdominal aortic aneurysm repair 3.
• Low-dose contrast CT protocols can provide accurate assessment of aortic diameters and access vessels 4.