Related Experiment Videos
Conventional CT of the aorta
1Department of Radiology, University of Washington Medical Center, Seattle 98195.
Insights
Computed tomography (CT) is a valuable tool for evaluating thoracic aortic aneurysms and dissections, offering advantages over aortography and MRI in many cases. A flexible approach to imaging is essential for accurate diagnosis and treatment planning.
Area of Science:
- Radiology
- Cardiovascular Imaging
- Diagnostic Imaging
Background:
- Computed tomography (CT) has significantly advanced the evaluation of thoracic aortic aneurysms and dissections.
- CT often serves as the primary imaging modality beyond plain radiography for these conditions.
Purpose of the Study:
- To compare the diagnostic capabilities of CT, aortography, and MRI in evaluating thoracic aortic aneurysms and dissections.
- To outline a workable strategy for selecting appropriate radiographic tests.
Main Methods:
- Review of CT, aortography, and MRI findings in thoracic aortic aneurysms and dissections.
- Comparison of the advantages and limitations of each imaging modality.
Main Results:
- CT excels in visualizing aneurysm walls, mural thrombus, and diagnosing dissection with clotted false channels.
- Aortography may be necessary for precise localization of arch aneurysms and assessing aortic insufficiency in acute dissections.
- MRI is suitable for stable patients or those intolerant to contrast agents, and for follow-up.
Conclusions:
- CT offers significant advantages in evaluating thoracic aortic aneurysms and dissections, particularly for non-invasive assessment and diagnosis of clotted dissections.
- A flexible, case-by-case approach to imaging selection is crucial for optimal patient management.
- CT is preferred for follow-up of treated aortic dissections due to its non-invasive nature and informative results.
Abstract:
The advent of CT has changed the way thoracic aortic aneurysms and dissections are evaluated. In many cases, CT is the only roentgenographic examination needed beyond plain radiograph. In evaluating aneurysm. CT's advantage over aortography is that it shows the wall and the mural thrombus, not just the contrast column. In some cases of aneurysm, however, particularly those arising near the aortic arch, aortography may be necessary to establish the precise location of the lesion with respect to the brachiocephalic arteries. In evaluating dissection, CT is less invasive and at least as accurate as aortography. As with aortography, the classic findings are contrast-filled multiple channels with intervening intimal flap(s). CT's particular advantage over aortography is that it permits diagnosis of dissection when blood in the false channel is clotted rather than free-flowing. In this case, the diagnosis can be made by demonstrating displaced intimal calcifications or the high-attenuation thrombus in the aortic wall or periaortic tissues. In cases of acute dissection for which emergency surgery is considered, however, aortography is preferred to CT because CT cannot provide information about aortic insufficiency or the condition of critical arterial branches such as the coronary, brachiocephalic, mesenteric, and renal arteries. In follow-up of treated aortic dissection CT is preferred over aortography because it is noninvasive and more informative. Compared with MRI, CT has the advantages of greater reliability and of compatibility with life-support apparatus. MRI is not able to depict calcification, so any displacement of calcification cannot be detected. MRI is most suitable for follow-up of treated patients or for acute patients who are stable or who cannot tolerate intravenous contrast agents. A flexible approach is essential in choosing the appropriate radiographic tests in the work-up of aortic dissection. In this article, a workable strategy is outlined, but the radiologist should not hesitate to change the order of tests or use a second test if results from one test are confusing or inconsistent with other clinical data.