Fig. 2

Double aortic arch. a Illustration showing the appearances of a double aortic arch, with a dominant right arch. The right arch gives off the right subclavian (RSC) and right common carotid (RCC) branches, while the left arch gives off the left subclavian (LSC) and left common carotid (LCC) arteries. Both the trachea and oesophagus are completely encircled and compressed by the vascular ring. b Axial CT scan shows the four-vessel sign. The first branch is the right subclavian (RSC) artery, the second is the right common carotid artery (RCC), the third is the left common carotid (LCC) artery and the fourth is the left subclavian (LSC) artery. c Axial MIP image shows bilateral aortic arches encircling the trachea and oesophagus. The right aortic arch (arrow) is larger than the left aortic arch (arrowhead). d Coronal reconstructed CT image at the level of the trachea shows a larger right arch (long arrow) and a smaller left arch (smaller arrow) encircling the trachea (asterisk). e Coronal MIP CT image at the level of the trachea shows similar-sized double arches in another patient (arrows). f 3D volume-rendered image exquisitely demonstrates the double aortic arch, with a dominant right arch (arrow) and a smaller left arch (arrowhead), both of which join the descending thoracic aorta (*), which is located on the left. g 3D volume-rendered image in another patient (same patient as e) demonstrates the double aortic arch, with similar sizes of the right arch (arrow) and the left arch (arrowhead), both of which join the descending thoracic aorta (*), which is located on the left. h Coronal volume-rendered image of the airway shows severe narrowing of the airway (arrow) by the double aortic arch