FLAIR Vascular Hyperintensities Indicate Slow Poststenotic Blood Flow in ICA Stenosis.

Abstract

Occlusion or significant stenosis of the internal carotid artery (ICA) in the cervical segment is commonly associated with apoststenotic decrease in the downstream blood flow and perfusion. Fluid attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH) are aphenomenon that represents slow arterial blood flow. In this study, we investigated the frequency and extent of FVH in the distal ICA in patients with proximal ICA stenosis. We analyzed the magnetic resonance imaging (MRI) findings in 51patients with atotal of 60cervical ICA stenoses with special focus on the frequency and extent of FVH in the area of the petrous segment of the ICA on FLAIR images and correlated these with Doppler/duplex sonography results. In 46(76.7%) patients with ICA stenosis, FVH could be detected in the petrous segment of the ICA: in 19(41.3%) patients athin hyperintense rim near the vessel wall (grade1), in 24(52.2%) patients astrong hyperintense rim near the vessel wall (grade2), and in 3(6.5%) patients ahyperintense filling of the entire lumen (grade3) was observed. The extent of FVH in the ICA in the petrous segment showed a high negative correlation with the poststenotic flow velocity (Spearman correlation, R = -0.75, p < 0.001), and moderate correlation with the degree of ICA stenosis (Spearman correlation, R = 0.51, p< 0.001). An FVH in the petrous ICA is commonly seen among patients with steno-occlusive disease in proximal ICA and could therefore be useful to recognize aproximal ICA stenosis even on FLAIR images.