title: Significance of hyperintense vessels on FLAIR MRI in acute stroke.
abstract: OBJECTIVE
  To describe hyperintense vessels sign (HVS) in patients with acute stroke on fluid-attenuated inversion recovery (FLAIR) MRI and determine its clinical significance and utility.
  
  
  BACKGROUND
  Enhancement of vessels on postcontrast MRI in patients with acute stroke is considered an indicator of early brain ischemia. Recently, the FLAIR technique has shown promise in earlier and better detection of ischemic brain parenchymal lesions.
  
  
  METHODS
  Two observers retrospectively reviewed 304 MRI of patients with stroke and identified 30 patients with acute middle cerebral artery stroke and HVS on FLAIR obtained within 24 hours of symptom onset. These patients were evaluated with contrast-enhanced MRI (n = 9), MR angiography of carotid and intracranial circulation (n = 30), cerebral angiography (n = 8), transcranial Doppler (n = 17), and SPECT (n = 16). The extent of HVS was compared with final infarct size and NIH Stroke Scale score.
  
  
  RESULTS
  HVS on FLAIR was seen in 10% of the patients with acute stroke. HVS was associated with large vessel occlusion or severe stenosis (>90%). Intravascular enhancement on contrast MRI was observed in vessels that were hyperintense on FLAIR. Both cortical and subcortical infarcts demonstrated HVS. MR angiographic and cerebral angiographic findings of large vessel occlusion or severe stenosis (>90%), slow flow, low velocities by transcranial Doppler, and hypoperfusion on SPECT correlated with HVS. HVS was the earliest ischemic change in three patients scanned within 3 hours of ictus. Final infarct size was smaller than the area showing HVS in all patients.
  
  
  CONCLUSIONS
  HVS on FLAIR MRI is an indicator of slow flow and early ischemia as a result of large vessel occlusion or stenosis and inadequacy of collateral circulation. HVS does not mean that infarction has occurred but indicates brain tissue at risk of infarction. It should prompt consideration of revascularization and flow augmentation strategies.
authors.affiliation: Lucy Dent Imaging Research Center, Millard Filmore Hospital, School of Medicine and Biomedical Sciences, State University of New York at Buffalo, USA.
authors.forename: S
authors.initials: S
authors.lastname: Kamran
authors.forename: V
authors.initials: V
authors.lastname: Bates
authors.forename: R
authors.initials: R
authors.lastname: Bakshi
authors.forename: P
authors.initials: P
authors.lastname: Wright
authors.forename: W
authors.initials: W
authors.lastname: Kinkel
authors.forename: R
authors.initials: R
authors.lastname: Miletich
mesh_terms: D000208:Acute Disease; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000175:diagnosis; D002536:Cerebral Arteries / Q000473:pathology*; D002544:Cerebral Infarction / Q000175:diagnosis*; D003097:Collateral Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D007089:Image Enhancement; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors