Figure 10. Penetrating atherosclerotic ulcer in a 61-year-old man with high blood pressure. Sagittal oblique contrast-enhanced MR angiogram shows a diffusely aneurysmal descending aorta with a large outpouching in the medial anterior region (arrow), an appearance consistent with penetrating atherosclerotic ulcer. Prior studies showed development of a focal aneurysm 2 years earlier.