Figure 16a. Rupture of penetrating atherosclerotic ulcer. (a) Unenhanced CT scan of the aortic arch shows an atherosclerotic aorta with displaced intimal calcifications (black arrow), subintimal hematoma (arrowhead), and hemothorax (white arrow). (b) Contrast-enhanced CT scan shows the ulcerated aortic lesion and outflow of contrast material from the aortic lumen (arrow).