Figure 8c.  Penetrating atherosclerotic ulcer. (a–c) CT angiograms (shown from superior [a] to inferior [c]) show a penetrating ulcer of the right lateral wall of the descending aorta (arrow in a and b) and distal intramural hematoma (arrowhead in c). (d) Sagittal MPR image shows the ulcer (arrow) and the intramural hematoma (arrowhead).