title: 3-T high-b-value diffusion-weighted MR imaging in hyperacute ischemic stroke.
abstract: OBJECTIVE
  In patients with hyperacute ischemic stroke, early demonstration of infarction is essential. Diffusion weighted imaging (DWI) is the key method for detecting hyperacute infarction. The value of high b-value DWI in hyperacute ischemic stroke is controversial at 1.5 T, and is unknown at 3 T. The aim of this study is to explore the value of high b-value versus standard b-value DWI at 3T in hyperacute stroke with quantitative and qualitative analysis.
  
  
  METHODS
  This study prospectively included 104 consecutive patients with hyperacute stroke. At 3 T, conventional MR sequences and DWI were performed. The examination included a standard DWI (b = 1000 s/mm(2)) and two high b-value DWI (b = 3000 s/mm(2) and b = 5000 s/mm(2)). Qualitative and quantitative analysis was performed.
  
  
  RESULTS
  With increasing b value, DW images appeared noisier. The number of detected lesions was significantly higher on b = 3000 images than on the other DW images and higher on b = 5000 images than on b = 1000 images. The number of lesions greater than 1 cm was not significantly different. Lesion conspicuity was higher, boundary better seen, lesion extent bigger, and estimation of final infarct size was better on high b-value than on standard b-value DWI. Contrast-to-noise-ratio (CNR) and signal-to-noise-ratio (SNR) decreased and contrast ratio (CR) increased on high b-value DWI compared to standard b-value DWI.
  
  
  CONCLUSIONS
  At 3 T, high b-value DWI was superior to standard b-value DWI in detection of hyperacute infarction and prediction of final infarct size in spite of increasing imaging artifacts.
authors: Division of Neuroradiology, Department of Neurosurgery, University of Freiburg Medical Center, Breisacher Str. 64, 79106 Freiburg, Germany. michael_lettau@gmx.de
authors: Michael
authors: M
authors: Lettau
authors: Mona
authors: M
authors: Laible
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D059629:Signal-To-Noise Ratio; D020521:Stroke / Q000175:diagnosis* / Q000473:pathology / Q000503:physiopathology
keywords: 3 Tesla; DWI; High b-value; Hyperacute ischemic stroke; MRI