|
FIG 1. Example of a DSA false-positive finding for basilar occlusion in a patient with low-flow state due to a severe stenosis of the left vertebral artery.
A and B, Frontal (A) and lateral (B) middle arterial phase DSA images show selective injection of dominant left vertebral artery (shown in anatomic orientation). Note the severe stenosis of the left vertebral artery (long arrow) and a small amount of reflux down the nondominant right vertebral artery (short curved arrow in A). The basilar artery distal to the origin of the left anterior inferior cerebellar artery is not opacified and therefore appears occluded (open arrow), even on late arterial and venous images (not shown).
C, Lateral projection, left ICA injection, middle arterial phase DSA image shows minimal retrograde filling of the distal basilar artery (arrow) through the posterior communicating artery to the level of the superior cerebellar arteries, suggesting segmental occlusion of the midbasilar artery.
D, Corresponding volume-rendered 3D CTA image in anatomic orientation. CTA image was obtained 3 days before DSA and shows a severe left vertebral artery stenosis (black arrow) associated with heavy calcific atheromatous plaque. However, CTA depicts the basilar artery as patent. In addition, the CTA image demonstrates two tandem stenoses of the distal basilar artery (white arrows), which may have contributed to impaired retrograde flow into the basilar artery via the posterior communicating artery upon anterior circulation injection at DSA. There was no change in patient symptoms during the intervening period between the CTA and DSA studies to suggest interval arterial thrombosis.
|