title: 3-Tesla versus 1.5-Tesla magnetic resonance diffusion and perfusion imaging in hyperacute ischemic stroke.
abstract: BACKGROUND
  Clinical 3-tesla magnetic resonance imaging systems are becoming widespread. No studies have examined differences between 1.5-tesla and 3-tesla imaging for the assessment of hyperacute ischemic stroke (<6 h from symptom onset). Our objective was to compare 1.5-tesla and 3-tesla diffusion and perfusion imaging for hyperacute stroke using optimized protocols.
  
  
  METHODS
  Three patients or their surrogate provided informed consent. Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) was performed sequentially at 1.5 T and 3 T. DWI, apparent diffusion coefficient (ADC) maps and relative time-to-peak (TTP) maps were registered and assessed. DWI contrast-to-noise ratio (CNR) and ADC contrast were measured and compared. The infarct lesion volume (ILV) and thresholded ischemic volume (TIV) were estimated on the ADC and TTP maps, respectively, with the penumbral volume being defined as the difference between these volumes.
  
  
  RESULTS
  Qualitatively, the 3-tesla TTP images exhibited greater feature detail. Quantitatively, the DWI CNR and ILV were similar at both field strengths, the ADC contrast was greater at 3 T and the TIV and penumbral volumes were much smaller at 3 T.
  
  
  CONCLUSIONS
  Overall, the 3-tesla diffusion and perfusion images were at least as good and in some ways superior to the 1.5-tesla images for assessing hyperacute stroke. The TTP maps showed greater feature detail at 3 T. The ischemic and penumbra volumes were much greater at 1.5 T, indicating a potential difference in the diagnostic utility of the PWI-DWI mismatch between field strengths.
authors: Department of Electrical and Computer Engineering, University of Calgary, Calgary, Alta., Canada.
authors: Robert K
authors: RK
authors: Kosior
authors: Caitlin J
authors: CJ
authors: Wright
authors: Jayme C
authors: JC
authors: Kosior
authors: Carol
authors: C
authors: Kenney
authors: James N
authors: JN
authors: Scott
authors: Richard
authors: R
authors: Frayne
authors: Michael D
authors: MD
authors: Hill
mesh_terms: D000369:Aged, 80 and over; D002545:Brain Ischemia / Q000150:complications* / Q000473:pathology; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D018810:Magnetic Resonance Angiography / Q000379:methods*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020521:Stroke / Q000209:etiology / Q000473:pathology*