From the Guidelines
Computed Tomography (CT) is the preferred modality for evaluating patients with suspected aortic arch aneurysms due to its high sensitivity and specificity, widespread availability, and ability to quickly diagnose the underlying condition and its extent. When choosing an imaging modality, the patient's history and clinical presentation, as well as institutional availability and expertise, should be considered 1. The advantages of CT include its ability to detect the presence and mechanism of aortic branch vessel involvement, vessel patency, signs of malperfusion, pericardial effusion, and hemopericardium, periaortic or mediastinal hematoma, and pleural effusion 1.
Some key points to consider when evaluating aortic arch aneurysms with imaging include:
- The use of electrocardiographic-synchronized CT techniques to accurately depict mediastinal structures, such as the proximal aorta and coronary ostia 1
- The consideration of alternative imaging modalities, such as echocardiography (TEE/TTE) or MRI, in certain clinical circumstances, such as patients with a history of iodinated contrast reaction or those who are too unstable to travel to the radiology suite 1
- The preference for TEE over TTE due to its higher sensitivity and better anatomic resolution, although TTE may be helpful in eliciting the diagnosis of aortic arch aneurysm and quickly identifying complications 1
- The use of MRI as a follow-up imaging modality in patients with diagnostic uncertainty or as the study of choice in stable patients with a contraindication to iodinated contrast 1.
From the Research
Imaging Modalities for Aortic Arch Aneurysm
- Computed Tomography (CT) angiography is considered the gold standard for aneurysm evaluation, allowing precise diameter assessment and accurate preoperative planning 2.
- Magnetic Resonance Angiography (MRA) is also used for the diagnosis of thoracic aortic aneurysms, providing functional and biomechanical information 3, 4.
- Ultrasound, including transthoracic and transesophageal echocardiography, is useful in the diagnosis and follow-up of proximal ascending aorta and abdominal aorta aneurysms, but may have limitations in assessing the aortic arch 3.
- Positron Emission Tomography (PET) can be used for the diagnosis of thoracic aortic aneurysms, but its role is less well established compared to CT and MRA 2.
Advantages and Limitations of Imaging Modalities
- CT angiography has the advantages of rapid image acquisition, multiplanar capacity, and wide availability, but has limitations including radiation exposure and the need for nephotoxic contrast administration 3, 5.
- MRA overcomes the limitations of CT angiography, providing functional and biomechanical information without the need for radiation or nephotoxic contrast, but may be less readily available 3.
- Ultrasound has the advantage of being non-invasive and widely available, but may have limitations in assessing the aortic arch and requiring skilled operators 3.
Role of Imaging in Diagnosis and Management
- Imaging plays a crucial role in the diagnosis, follow-up, and management of aortic aneurysms, including assessing aneurysm size, location, and etiology 3, 4, 2, 6.
- Imaging is used to determine the appropriate timing of surgical replacement and the type of procedure necessary, making it essential for radiologists to understand the clinical implications of their findings 6.
- Postoperative imaging is also important, as it can impact how patients are treated and what complications may arise 6.