Periaortic Structures and Aortic Branch Vessel Origins

Structures immediately adjacent to the aorta (for example, the anterosupe-rior pericardial recess or the left brachiocephalic vein) can mimic a double lumen and may be confused with dissection (Figure 5.4). The same applies to aortic branch vessel origins, which can simulate the presence of an intimal flap7. Familiarity with the anatomy and, in difficult cases, image review in multiple planes can aid in avoiding these pitfalls.

Periaortic

Figure 5.2. Axial contrast-enhanced CT images of classic type A dissection in a patient with prior sternotomy: (a) shows dissection flap in the aortic arch (long white arrow) (the false lumen is indicated by the short black arrow); (b) shows extension of the dissection flap into the bra-chiocephalic arteries (the flap does not occlude those branches, and perfusion is not impaired); streak artifact from metallic sternotomy wires and concentrated contrast in the superior vena cava (white arrowhead) is also demonstrated.

Figure 5.2. Axial contrast-enhanced CT images of classic type A dissection in a patient with prior sternotomy: (a) shows dissection flap in the aortic arch (long white arrow) (the false lumen is indicated by the short black arrow); (b) shows extension of the dissection flap into the bra-chiocephalic arteries (the flap does not occlude those branches, and perfusion is not impaired); streak artifact from metallic sternotomy wires and concentrated contrast in the superior vena cava (white arrowhead) is also demonstrated.

Figure 5.3. Axial contrast-enhanced CT images of motion artifact simulating dissection of the ascending aorta: (a) black arrow indicates apparent peripheral low attenuation rim in the ascending aorta mimicking dissection; (b) white arrows indicate apparent double contour of calcifications in the ascending aorta, mimicking chronic dissection with calcified false lumen.

Figure 5.3. Axial contrast-enhanced CT images of motion artifact simulating dissection of the ascending aorta: (a) black arrow indicates apparent peripheral low attenuation rim in the ascending aorta mimicking dissection; (b) white arrows indicate apparent double contour of calcifications in the ascending aorta, mimicking chronic dissection with calcified false lumen.

Figure 5.4. Axial contrast-enhanced CT images of left brachiocephalic vein simulating dissection of the brachiocephalic artery: (a) shows junction of left brachiocephalic vein (black arrow) and SVC (white arrow) (black arrowhead indicates origin of brachiocephalic artery from the aortic arch); (b) image superior to (a) shows left brachiocephalic vein (black arrow) adjacent to brachiocephalic artery (black arrowhead), simulating dissection; (c) image superior to (b) shows left brachiocephalic vein (black arrow) coursing anterior to brachiocephalic artery (black arrowhead).

Figure 5.4. Axial contrast-enhanced CT images of left brachiocephalic vein simulating dissection of the brachiocephalic artery: (a) shows junction of left brachiocephalic vein (black arrow) and SVC (white arrow) (black arrowhead indicates origin of brachiocephalic artery from the aortic arch); (b) image superior to (a) shows left brachiocephalic vein (black arrow) adjacent to brachiocephalic artery (black arrowhead), simulating dissection; (c) image superior to (b) shows left brachiocephalic vein (black arrow) coursing anterior to brachiocephalic artery (black arrowhead).

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