Multimodality Imaging of Thoracic Aortic Diseases

Bhave NM, Nienaber CA, Clough RE, Eagle KA.
Multimodality Imaging of Thoracic Aortic Diseases in Adults. JACC Cardiovasc Imaging 2018;11:902-919.

The following are key points to remember from this article about multimodality imaging of thoracic aortic diseases in adults:

  1. Multimodality imaging, including transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), computed tomography angiography (CTA), and magnetic resonance angiography (MRA), are the mainstays of aortic imaging and permit the diagnosis and follow-up of acute aortic syndromes (AAS).
  2. Chest radiography is one of the most common tests to initially evaluate patients with chest pain or dyspnea. While it will usually demonstrate mediastinal abnormalities in patients with thoracic aortic dissection, up to 15% of patients with a type B thoracic aortic dissection may have a normal chest x-ray.
  3. The preferred modality for patients with suspected thoracic aorta disease is generally CTA given its availability, speed, and accuracy. An appropriate protocol, including ECG gating, is important to optimize accuracy.
  4. MRA is an alternative to CTA in stable patients being evaluated for AAS. MRA can be useful to distinguish intramural hemorrhage from mural thrombus. Dynamic MRA can quantify flow in the true and false lumens, and is being investigated for a possible role in identifying patients with decreased organ perfusion who may benefit from intervention.
  5. Patients with suspected thoracic aortic disease often have TTE performed early. While its sensitivity to detect AAS is limited, pathology in the aortic root and proximal ascending aorta can often be visualized, and complications such as pericardial effusion or aortic regurgitation can be identified. Assessment of the remainder of the aorta is limited, and artifacts present diagnostic challenges.
  6. TEE has slightly lower sensitivity than CTA and MRA with similar specificity, particularly due to a blind spot in the distal ascending aorta and proximal arch. This procedure requires sedation and does not visualize the abdominal aorta.
  7. The use of positron emission tomography with fluorodeoxyglucose is currently being investigated to potentially identify patients with AAS and active inflammation at risk of aortic disease progression.
  8. Thoracic aortic aneurysms require careful follow-up to assess size and changes in size over time. Both CTA and MRA can be used to follow sizes. While CTA has higher spatial resolution and is faster, MRA does not expose the patient to radiation or iodinated contrast. TTE can be useful to follow aortic aneurysms limited to the aortic root and proximal ascending aorta when they are well visualized with this modality.
  9. Inter-modality agreement between aorta measurements can be adequate using certain techniques, although there are important differences in measurement conventions between tests, including whether the aorta wall is included in the measurement. For serial testing, direct comparison of images is important to assess for change.
  10. There is a need for improved risk prediction models that investigate both clinical and imaging variables to identify patients at higher risk of events. Improved imaging techniques are being studied to improve our understanding of thoracic aortic disease and progression.

Clinical Topics: Cardiac Surgery, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Pericardial Disease, Valvular Heart Disease, Vascular Medicine, Aortic Surgery, Cardiac Surgery and Heart Failure, Cardiac Surgery and VHD, Interventions and Imaging, Interventions and Structural Heart Disease, Interventions and Vascular Medicine, Angiography, Computed Tomography, Echocardiography/Ultrasound, Magnetic Resonance Imaging, Nuclear Imaging

Keywords: Aneurysm, Dissecting, Aorta, Abdominal, Aortic Aneurysm, Aortic Aneurysm, Thoracic, Aortic Diseases, Aortic Valve Insufficiency, Cardiac Surgical Procedures, Chest Pain, Coronary Angiography, Diagnostic Imaging, Dyspnea, Echocardiography, Transesophageal, Electrocardiography, Magnetic Resonance Angiography, Pericardial Effusion, Positron-Emission Tomography, Risk, Thrombosis, Tomography, X-Ray Computed, X-Rays

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