title: 3-T high-b-value diffusion-weighted MR imaging of hyperacute ischemic stroke in the vertebrobasilar territory.
abstract: OBJECTIVE
  Diffusion-weighted imaging (DWI) is the key method for diagnosing acute ischemic stroke. Applied b values in stroke diffusion studies are usually in the range of 800-1500 s/mm², but progress in magnetic resonance (MR) technology now permits higher b values. However, it is uncertain whether high-b-value DW sequences improve the detection of acute and hyperacute ischemic lesions. The aim of this study is to explore the sensitivity of high b values vs standard b values at 3T in hyperacute stroke in the vertebrobasilar territory.
  
  
  METHODS
  3-T DWI was performed in referred patients with a clinical diagnosis of hyperacute (<6h from onset) cerebral infarction using conventional MR sequences as well as DW sequences. Examinations included the usual DW sequence (b=1000 s/mm²) and two high-b-value DW sequences (b=3000 s/mm² and b=5000 s/mm²). Patients with hyperacute stroke in the posterior circulation were included if MR imaging, including the usual DW sequence, was normal or if the diagnosis was uncertain.
  
  
  RESULTS
  In all six studied patients, ischemic lesions were better visualized with high-b-value DWI compared with the usual DWI. On increasing the b value, DW images appeared to be noisier while white-matter tracts became progressively hyperintense.
  
  
  CONCLUSIONS
  At 3T, high-b-value DW sequences may be helpful for diagnosing hyperacute infarctions in the vertebrobasilar territory, but further studies are needed to confirm this hypothesis.
authors.affiliation: Division of Neuroradiology, Department of Neurosurgery, University of Freiburg Medical Center, Breisacher Str. 64, D-79106 Freiburg, Germany. michael_lettau@gmx.de
authors.forename: Michael
authors.initials: M
authors.lastname: Lettau
authors.forename: Mona
authors.initials: M
authors.lastname: Laible
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001488:Basilar Artery; D002545:Brain Ischemia / Q000175:diagnosis*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis*; D014711:Vertebral Artery