Vulnerable plaque is analogous to plaque in the coronary arteries, and has a lipid core with a fibrous cap. When the fibrous cap comes off, the lipid core is expunged and the plaque ulcerates. The consequences are embolization distally, as well as the presence of small ulcers, which can become deep. This is the etiology of the so-called penetrating ulcer. These occur in the ascending aorta or arch and, more commonly, in the descending aorta.
Ulcerated plaque can occur anywhere.
As the world population increases in age, there will be more penetrating atherosclerotic ulcers occurring more proximally. Although this course is on MRA, CT can demonstrate protruding atheromas in the ascending aorta. Figure 4 shows a 5-mm atheroma and a large atheroma in the descending aorta. CT fluoroscopy would be required in order to look for mobility. There is another, very large, protruding mobile atheroma on a stalk.