Figure 13. Figures 12, 13. (12) Calcified false lumen. Venous-phase enhanced CT scan shows an abdominal aortic dissection with mural calcification of the false lumen (arrows). (13) Three-channel aorta. CT angiogram shows two false lumina (F) in the thoracic descending aorta. The intimal flap demonstrates the Mercedes-Benz sign.