Abstract
Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH) are commonly encountered on MR imaging studies performed shortly after the onset of acute ischemic stroke. Prior reports have speculated regarding the pathogenesis of this finding, yet definitive correlative angiographic studies have not been performed. We studied the pathophysiologic and hemodynamic correlates of FVH on conventional angiography and concurrent MR imaging sequences. Retrospective review of FLAIR and gradient-refocused echo MR imaging sequences acquired immediately before conventional angiography for acute stroke was conducted in a blinded fashion. The presence, location, and morphology of FVH were noted and correlated with markers of thrombotic occlusion and collateral flow on angiography. Angiographic collaterals were graded on a 5-point scale incorporating extent and hemodynamic aspects. A prospective ischemic stroke registry of 632 patients was searched to identify 74 patients (mean age, 63.4 +/- 20 years; 48% women) having undergone FLAIR sequences immediately before angiography. Median time from FLAIR to angiography was 2.9 hours (interquartile range, 1.1-4.7 hours). FVH were present in 53/74 (72%) of all acute stroke cases with subsequent angiography. FVH distal to an arterial occlusion were associated with a high grade of leptomeningeal collateral blood flow. FVH are observed in areas of blood flow proximal and distal to stenosis or occlusion and are noted with more extensive collateral circulation.
Highlights
AND PURPOSE: Fluid-attenuated inversion recovery (FLAIR) vascular hyperintensities (FVH) are commonly encountered on MR imaging studies performed shortly after the onset of acute ischemic stroke
FLAIR vascular hyperintensities (FVH) can be found in the setting of acute stroke due to large-vessel stenosis[4] or occlusion.[3]
Subjects were included in this study if they presented with acute ischemic stroke or transient ischemic attack (TIA) and underwent MR imaging of the brain followed by cerebral digital subtraction angiography (DSA) within 6 hours of the MR imaging
Summary
Retrospective review of FLAIR and gradient-refocused echo MR imaging sequences acquired immediately before conventional angiography for acute stroke was conducted in a blinded fashion. Subjects were included in this study if they presented with acute ischemic stroke or transient ischemic attack (TIA) and underwent MR imaging of the brain followed by cerebral DSA within 6 hours of the MR imaging. Patients were excluded if they presented with aneurysm or hemorrhagic stroke, if their MR imaging did not include a FLAIR sequence, and if their MR imaging or DSA images were not available for review. In addition to FLAIR sequences, diffusionweighted images (DWI), perfusion-weighed images (PWI), T2*weighted gradient echo, and 3D time-of-flight intracranial MR angiography (MRA) sequences were reviewed if available to confirm the vascular territory of the ischemia
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