PMC9935957_01
Coexistence of separate origins of the left ICA and ECA from the aortic arch and the anomalous origin of the left VA from the aortic arch in a 10-year-old girl.. A. A time-of-flight MR angiography maximum intensity projection image is presented. The anteroposterior view of the intracranial arteries depicts the diffuse narrowing of the left distal ICA. The diameter of the left distal ICA became is to that of the right distal ICA (arrow) at distal locations beyond the origin of the left posterior communicating artery (arrowhead).. B. Left anterior oblique and lateral projections of three-dimensional volume-rendered CT angiography reveal five vessels that originate directly from the aortic arch: right brachiocephalic trunk (B), left ECA (E), left ICA (I), left VA (V), and LS.. C. The axial CT image shows that the diameter of left ICA (arrow) is smaller than those of the right ICA (arrowhead) and left ECA (blank arrow).. D. The axial CT image shows that the left carotid canal (arrow) is narrower than the right carotid canal (arrowhead).. E. The axial CT image acquired at the 6th cervical vertebra level shows the right VA (arrowhead) located in the right transverse foramen. The left VA (arrow) is not visible in the left transverse foramen in this figure, but it is located anteriorly.. B = brachiocephalic artery, E = left ECA, ECA = external carotid artery, ICA = internal carotid artery, I = left ICA, LS = left subclavian artery, RS = right subclavian artery, V = left VA, VA = vertebral artery
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On intracranial MRA, the left ICA showed diffuse narrowing up to the fetal type of the posterior communicating artery (Fig. 1A). Subsequent head and neck CTA revealed the agenesis of the left CCA with separate origins of the left ICA and ECA from the aortic arch (Fig. 1B). On axial CT images, the diameters of the left ICA and ipsilateral carotid canal were smaller than those of the contralateral ICA, which was a consistent finding to that of intracranial MRA (Fig. 1C, D). The left VA was also directly originated from the aortic arch with anomalous entering into the transverse foramen at the 5th cervical vertebra, which was at a lower level than the contralateral side (Fig. 1E).