Figure 4b. (a, b) Electron-beam CT images of a double aortic arch. (a) The dominant right arch (arrow) and smaller left arch (arrowhead) are diagnostic of a double aortic arch vascular ring. (b) Image obtained slightly inferior to a shows the uniting descending aortas (arrow) slightly to the left of the midline. (Images courtesy of J. Kuhn, MD, Buffalo Children’s Hospital, New York.) (c-e) Three-dimensional spiral CT reconstructions of a double aortic arch with a dominant right arch. (c) Anterior and (d) posterior views, and (e) view from above are shown. (Images courtesy of Ronald Cohen, MD, Children’s Hospital, Oakland, Calif.)