Findings
-The CXR demonstrates a widened mediastinum, indistinct aortic knob, and mediastinal shift to the right.
-The CT demonstrates an intimal flap in the descending aorta, a widened mediastinum secondary to periaortic hematoma, and a left-sided pleural effusion.
Discussion
-Aortic transection or rupture usually occurs as a result of high-impact blunt trauma e.g. MVA. 75%-90% result in immediate death. 18% of MVA-related deaths are secondary to aortic transection. Aortic transection is second only to head injury as the leading cause of injury-related death. Aortic transection must be distinguished from aortic dissection, which is a separation of the layers of the aortic wall, usually caused by a tear in the weakened intima. This patient demonstrates both with mediastinal hemorrhage and a Stanford Type B dissection.


http://eradiology.bidmc.harvard.edu/Classics/item.aspx?section=Emergency+Radiology&labelpk=33f0adab-853f-4010-a0e2-0756b3f1eac5&pk=6e919e0b-2a48-409b-a53c-32e51be6165a

Findings
-The CXR demonstrates a widened mediastinum.
-The CT demonstrates the intimal flap in the ascending and descending thoracic aorta.
Discussion
-Aortic dissection is the separation of the layers of the aortic wall, usually caused by a tear in the weakened intima . Aortic dissection is the most common fatal condition involving the aorta. The Stanford Classification has 2 types: Type A (60%) involves the ascending aorta. It may involve the arch or descending aorta to varying degrees. Type B (40%) involves the arch and/or descending aorta but not the ascending aorta. This is a Stanford type A aortic dissection, involving the origins of most of the aortic arch vessels. Notice that the aortic knob is still distinct and there is no mediastinal hematoma which differentiates this from an aortic transection.


http://eradiology.bidmc.harvard.edu/Classics/item.aspx?section=Emergency+Radiology&labelpk=33f0adab-853f-4010-a0e2-0756b3f1eac5&pk=f754f9fb-33f0-4a73-9afd-47845e2c601a

Magnetic resonance imaging is as accurate as CT and arteriography in the detection of aortic dissection6. The MR diagnosis of an aortic dissection requires the demonstration of an intimal flap, which can be easily identified when both the true and false lumina appear as signal void areas on SE images .

Reference:BiblioMed Textbook-Computed Body Tomography

Dissection of the aorta usually originates in the thorax but sometimes extends into the abdomen. Its diagnosis is based on demonstration of an intimal flap with enhancement of both the true and false lumina after intravenous administration of contrast medium



Reference:BiblioMed Textbook-Computed Body Tomography

type B,penetrating athero-sclerotic ulcer

type B,penetrating athero-sclerotic ulcer

enhancing atelectasis mimiking aortic dissection

small atelectatic lung simulating type B

dissecting aneurysm.

type B,ruptured

type B

multiple false lumina

type B

type B

type B

type B

type A

type A

type A

type B with renal ischemia