American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the first-line imaging approach in suspected acute aortic dissection?

1. Ultrasound

2. CT aortography

3. X-ray

4. MRI

The correct answer is: CT aortography

The first-line imaging approach in suspected acute aortic dissection is CT aortography. This imaging modality is preferred due to several key factors that enhance its effectiveness in diagnosing aortic dissections. CT aortography provides rapid imaging with high sensitivity and specificity, enabling clinicians to visualize the aorta in detail and identify the presence of a dissection, its location, and any associated complications such as hemorrhage or involvement of branch vessels. The method employs intravenous contrast material, which enhances the vascular structures, making it easier to differentiate between the true and false lumens of the aorta. In contrast, while other imaging modalities like ultrasound, X-ray, and MRI can be useful in certain contexts, they do not provide the same level of detail or speed as CT aortography. Ultrasound can have limitations in visualizing the entire aorta and may be operator-dependent, while X-ray is not sensitive enough to detect dissections accurately. MRI, although excellent for soft tissue evaluation, is less accessible in emergency settings and typically requires more time to perform, which may delay critical decision-making. Therefore, the superior characteristics of CT aortography make it the gold standard for rapid diagnosis in cases of suspected acute aortic dissection.