PMC4053235_01
Left internal carotid injection. The arrowhead shows an azygous A2 from which both the pericallosal arteries arise.
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fig1
Computed tomographic angiogram showing the azygous A2.
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fig2
Left vertebral artery injection. There is no filling of the PICA and the corresponding territory.
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fig3
The right and left vertebral arteries were unremarkable for aneurysm or stenosis, but the left vertebral artery showed agenesis of the left PICA with no opacification of the corresponding cerebellar territory (Figure 3).
Right vertebral injection. The right PICA gives branches to supply the PICA territory in the left hemisphere.
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fig4
The PICA branching from the right vertebral artery was enlarged and crossed the midline to supply both cerebellar hemispheres (Figure 4).