How is Aortic Dissection diagnosed?

How do you diagnose a an aortic dissection? So listening to what the patient is telling you about the symptoms that they have developed, thinking about the risk factors that the patient has for a dissection. Blood tests are not particularly useful although there is one called a D-dimer which is a test for abnormal clotting often used to diagnose pulmonary embolism but chiefly it's CT scan and that is the investigation of choice and really the only investigation that can categorically diagnose an aortic dissection.