Figure 1
Axial image from thin-section 3D TOF shows the PTA originating from the left internal carotid artery (LICA) (small arrow) and duplicating at the same level due to tortuosity (large arrows).
Figure 2
MIP image from 3D TOF MR angiography shows the PTA in the carotid canal on the left side (arrow).
Figure 3
MIP image from 3D TOF MR angiography shows left anterior cerebral artery bifurcation and trifurcation resulting from bifurcation (arrow). Early bifurcation and trifurcation at the level of MCA is also seen.
Figure 4
Axial MIP image from 64-slice MDCT shows the PHA passing through the enlarged hypoglossal canal on the right side (arrow).
Figure 5
3D volume-rendering image from 64-slice MDCT shows the PHA crossing over the RICA and entering the hypoglossal canal (arrow).
Figure 6
3D volume-rendering image from 64-slice MDCT shows the PHA coursing as the basilar artery (thick arrow) after passing through the hypoglossal canal (thin arrow). True agenesis of the basilar artery is also seen.
Figure 7
Coronal MIP image from 64-slice MDCT shows severe hypoplasia in the bilateral vertebral arteries in the patient with PHA (Case 2) (black arrows).
Figure 8
Coronal MIP image from 64-slice MDCT shows the POA exiting from the carotid canal and coursing parallel to the basilar artery (arrow).
Figure 9
Volume-rendering image from 64-slice MDCT shows the POA coursing parallel to the basilar artery (arrow).
Figure 10
Axial MIP image from 64-slice MDCT shows the POA coursing parallel to the PCA on the anterior side (arrow).
Figure 11
Coronal MIP image from 64-slice MDCT shows the POA joining the M1 segment of the MCA through an accessory PCoA (arrow).
Figure 12
Axial MIP image from 64-slice MDCT shows the hypoplasia in the PCoA and the duplication of the posterior cerebral artery in the patient with POA (Case 3) (arrow).