the Acute Aortic Syndrome

The term Acute Aortic Syndrome (AAS) is used to describe three closely related emergency entities of the thoracic aorta:

classic Aortic Dissection (AD),

Intramural Hematoma (IMH) and 

Penetrating Atherosclerotic Ulcer (PAU).
 

Clinically these conditions are indistinguishable.
CT is the most accurate imaging modality for the initial diagnosis, differentiation and staging.

Typical Aortic Dissection, Intramural Hematoma and Penetrating Aortic Ulcer.