How can you differentiate the true lumen from the false one on CTA?
Features generally indicative of the true lumen included outer wall calcification and eccentric flap calcification (seen in the aortic arch of this case). The true lumens (smaller) are often compressed by the false lumens. The false lumen, on the other hand, can be identified from the beak sign (seen in this case) as well as often being larger (under higher false luminal pressure). In cases showing one lumen wrapping around the other lumen in the aortic arch, the inner lumen is the true lumen.
How does this case get treated?
Immediate surgical repair is the only option for Stanford A dissections.
There is a dissection flap which has involved the aortic root, extending to the arch as well as reaching to the abdominal aorta, below its bifurcation, consistent with Stanford A aortic dissection.
It is difficult to properly assess the coronary arteries as the images are not gated.
The flap extends to the aortic arch, which appears to have also involved brachiocephalic truck as well as left common carotid artery (images more cranial not shown). While the left subclavian artery appears to have been taken off from the true lumen of the aortic arch.
There is a large wedge shaped hypoattenuated area in the left kidney, consistent with renal infarction probably as a result of flap extending to the left renal artery.
The right renal artery appears to be originating from the true lumen, with a normally enhancing right kidney.
The true lumen also gives rise to the celiac axis, superior mesenteric as well as inferior mesenteric arteries. The celiac axis anatomy is conventional.
The dissection flap extends below the aortic bifurcation and involves the proximal parts of external as well as internal iliac arteries on the right side. On the left side, the flap is similarly involving the left common iliac artery (which becomes nearly totally unopacified distally), with only trace of contrast seen in the proximal few centimetres of left external as well as internal iliac arteries (the contrast opacification reconstitues afterwards).
No pericardiac or pleural collection identified.
No bowel wall thickening/retroperitoneal hematoma.
Large left renal cyst.