Imaging description

Axial images of the aorta that are perpendicular to a penetrating atherosclerotic ulcer may demonstrate a displaced intimal flap (Figure 56.1), suggestive of a dissection. However, upon inspection of the coronal oblique multiplanar reformats, penetrating atherosclerotic ulcers (PAUs) are easily distinguished from dissection (Figure 56.2). Penetrating atherosclerotic ulcers will communicate with the aortic lumen via a single, narrow-necked intimal defect. Dissections communicate with the aorta through at least two separate intimal defects at the proximal entry point and the distal exit point with an intervening false lumen. The appearance of a pseudodissection from large PAUs occurs when the PAU is viewed in a plane perpendicular to its long axis. At the levels near the proximal and distal neck of the ulcer where the PAU projects along the long axis of the aorta, the wall of the ulcer compressed against the wall of the aorta can simulate a displaced intimal flap.

Importance

Distinguishing between a large PAU and an aortic dissection is important for the immediate management of the patient. A type B dissection is typically managed without surgical intervention. However, an enlarging PAU, such as in this patient, may lead more expediently to surgical repair, particularly if the patient is acutely symptomatic.

Typical clinical scenario

Penetrating atherosclerotic ulcers and aortic dissection lie on the spectrum of acute aortic syndrome. When symptomatic, PAUs can have a similar clinical presentation to acute aortic dissection, consisting of a sudden onset of chest pain and discomfort. There is debate as to whether penetrating atherosclerotic ulcers can progress to aortic dissection. PAUs are often discovered incidentally during CT angiography.

Differential diagnosis

Differential considerations for an apparent displaced intimal flap commonly include aortic dissection or traumatic aortic injury, as well as artifacts from beam hardening or cardiac motion. However, this case illustrates that in patients with severe atherosclerosis and hypertension, a large PAU resulting in a pseudodissection should also be considered. Multiplanar reformats are valuable in cases such as these to distinguish between true dissections and large PAUs imitating dissection.