Intra-arterial FLAIR Hyperintensity

Arterial segments proximal and distal to areas of stenosis or occlusion have been shown to demonstrate high signal on FLAIR images. This finding is seen in acute stroke and may be transient.

Increased FLAIR signal is thought to reflect altered hemodynamic and is seen with high grade of collateral circulation. Here we see intra-arterial FLAIR hyperintensity in the basilar artery.

Reference

Sanossian N, et al. Angiography Reveals That Fluid-Attenuated Inversion Recovery Vascular Hyperintensities Are Due to Slow Flow, Not Thrombus. Am J Neuroradiol, 2009; 30(3): 564-568.