Summary of studies describing FLAIR vascular hyperintensities

Author (Publication Year)	Population Studied	No.	Age Range/Mean (yr)	Criteria for FVH Diagnosis	Study	Conclusions
Cosnard et al (1999)³	Acute cerebral ischemia imaged <6 hours from symptom onset	53	26–90/69	High signal from vessels on FLAIR sequences	Comparison of 3D-TOF MRA and FLAIR images for stroke diagnosis	FVH corresponded to MRA evidence of stenosis/occlusion; FVH correlated to the territory of brain infarction on follow-up imaging in 85% of cases
Kamran et al (2000)⁴	Retrospective blinded analysis of 304 MRIs of patients admitted for acute MCA stroke	30	52–81	Tubular hyperintense signal relative to gray matter on FLAIR	Determined the clinical correlates of FVH	FVH observed in 10% of cases; FVH associated with MCA occlusion or severe stenosis; Angiographic studies correlated FVH with slow flow in leptomeningeal collaterals; NIHSS scores higher in patients demonstrating greater burden of FVH in MCA territory
Maeda et al (2001)⁵	Review of patients imaged within 6 hours of stroke-symptom onset	11	63–88/74	Arterial hyperintensity on FLAIR images	Comparison of FVH with DWI for diagnosis of acute stroke	FVH present in 8 of 11 patient MRIs; FVH can precede DWI abnormalities and may provide a clue to early detection of impending infarction
Toyoda et al (2001)⁶	Imaging within 6 hours of onset of acute cerebral ischemia caused by intracranial arterial occlusion	60	27–93/70.3	HVS	Described FVH, MRA, flow voids on T2, and DWI findings in select group	FVH present in 98%; FVH seen in areas outside increased DWI signal; Final infarct volume intermediate to DWI signal area and FVH area
Iancu-Gontard et al (2003)⁸	Cases with multiple intracerebral arterial stenoses imaged nonacutely with FLAIR and control group	19 vs 19	Study group (22–67/43), control group (42.2)	HVS on FLAIR = focal or tubular hyperintensities in the subarachnoid space (within dark CSF signal)	Determined whether HVS is more common in patients with known intracerebral arterial stenosis	High inter-reader concordance in identifying FVH; FVH seen in 68% of cases and 5% of controls; Concordance of territorial distribution of stenoses on FVH highest in MCA distribution; FVH seen mostly in high-grade stenosis or occlusion
Schellinger et al (2005)¹²	Review of 127 patients who received rtPA within 3 hours of stroke onset	56	63–89/76	HVS	Comparison of HMCAS, GRE-BA, and FVH for diagnosis of stroke and predicting response to rtPA	FVH associated with vessel occlusion but has little prognostic value; FVH more sensitive than HMCAS and GRE-BA in diagnosis if large-vessel occlusion (66% vs 40% vs 34%); HVS represents slow flow whereas the other 2 signs represent the thrombus; FVH not an independent predictor of intracranial hemorrhage, recanalization, and clinical outcome, including response to rtPA
Sanossian et al (2009)⁹	Acute cerebral ischemia imaged within 6 hours of angiography	74	43–83/63	Focal, tubular, or serpentine hyperintensity relative to gray matter in the subarachnoid space or extending into the parenchyma	Description of the correlates of FVH on concurrent angiography	FVH was present in 53/74 (72%) of all acute strokes with subsequent angiography; FVH was seen in areas of blood flow proximal and distal to stenosis or occlusion; FVH distal to high-grade arterial occlusion is associated with a high-grade leptomeningeal collateral blood flow
Lee et al. (2009)¹⁰	Consecutive patients with MCA territory infarct imaged prior to treatment with rtPA	52	54–84/69	Linear- or serpentine-appearing hyperintensity on FLAIR imaging, corresponding to a typical arterial course in the hemisphere of arterial occlusion	Study of the hemodynamic correlates of FVH	FVH observed distal to arterial occlusion in 73% and proximal to 77% of patients; FVH due to collateral flow beyond the site of occlusion; FVH associated with smaller ischemic lesion volumes, as well as lower initial NIHSS scores; The presence of distal FVH before rtPA is associated with large diffusion-perfusion mismatch; FVH not an independent predictor of 5-day NIHSS