Showing today preoperative radiographs of 57-year-old man with a torn knee cartilage. Sorry about the poor quality of the lateral view.
What do you see?
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Findings: PA radiograph show widening of the right superior mediastinum (A, arrow), imprinting the tracheal wall (A, red arrow).
In the lateral view there is increased opacity of Raider triangle (B, circle) with slight bowing of the posterior tracheal wall (B, red arrow).
The main causes of occupation of Raider triangle are two: either esophageal disease or congenital malformation of the aortic arch. The last one is the most likely, given the findings in the PA view.
Enhanced CT confirms a right aortic arch (C-D, arrows), crossing behind the trachea (C-E, red arrows) and causing the opacity in Raider triangle.
Findings are better seen in the 3-D reconstruction (F).
Final diagnosis: right aortic arch
Congratulations to Jolanta who made the correct diagnosis (my initial impression in the plain film was double aortic arch, so I will award another prize to Faelivrin for being wrong with me).
Teaching point: this case does not look very exciting, but right aortic arch is very common, and it is important to avoid confusing it with a mediastinal mass.
If you want to know more about malformations of the aortic arch, look up the article by Hanneman, Newman and Chan: Congenital variants and anomalies of the aortic arch, RadioGraphics 2017; 37:32–51