case_images: PMC8411611_01
case_images: Chest CT angiography of a 2 years old toddler, in axial (A) and coronal (B-D)
  reconstructions, showing a balanced double aortic arch with a right arch (RA) and left
  arch (LA) having an equal diameter forming a vascular ring around the trachea (A)
  joining together to the descending aorta (B). From each arch arises a common carotid
  artery (yellow arrow) and a subclavian artery (yellow arrow) forming a "four vessels"
  sign (C and D).
case_images: 10.1177_2333794X211039649-fig1.jpg
case_images: PMC8411611_01_10.1177_2333794X211039649-fig1.jpg
case_images: fig1-2333794X211039649
case_images: The left arch and right arch have almost equal diameters (right arch = 18.9 mm, and left arch = 19.5 mm) and from each arch arises a common carotid artery and subclavian artery, forming a "four vessel" sign (Figure 1).