The aortic isthmus.
In chest radiographs of seven infants, the aortic knob, isthmus, and descending aorta rendered a figure 3 image identical to that seen in coarctation of the aorta. Awareness of this anatomic variation may aid in diagnosis and may help to prevent unnecessary cardiac catheterization.
D001013:Aorta, Thoracic / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D001017:Aortic Coarctation / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D011859:Radiography