Acute aortic syndromes refer to the spectrum of aortic emergencies that include aortic dissection, intramural hematoma, penetrating atherosclerotic ulcer of the aorta, aortic aneurysm leak and rupture, and traumatic aortic transection. The aortic wall is composed of three layers (Fig. 1): the inner layer of intima, the middle layer of media, and the outer layer of adventi-tia. Multiple mechanisms are involved in the disruption of the aortic wall layers, leading to various acute aortic syndromes. This pictorial essay focuses on the distinction of a typical aortic dissection from an intramural hematoma and penetrating atherosclerotic ulcer.