title: Transcranial Doppler markers of diffusion-perfusion mismatch.
abstract: OBJECTIVE
  During the evaluation of acute ischemic stroke with diffusion- and perfusion-weighted magnetic resonance imaging (DWI and PWI, respectively), the presence of salvageable brain tissue is suggested by the occurrence of a perfusion-diffusion "mismatch." DWI and PWI, however, are not universally available and have inherent inconveniences, which justify a search for practical diagnostic alternatives. The purpose of this study is to investigate whether there are transcranial Doppler (TCD) markers of mismatch.
  
  
  METHODS
  Retrospective analysis of 22 patients with acute ischemic stroke affecting the middle cerebral artery (MCA) territory, who had a TCD performed within 24 hours of magnetic resonance imaging (MRI) with DWI and PWI.
  
  
  RESULTS
  MRI and TCD were performed on average 10.8 +/- 9.2 hours apart. Time from symptom onset to MRI and TCD completion were 1.6 +/- 1.6 and 2 +/- 1.9 days, respectively. MCA and intracranial internal carotid artery (ICA) cerebral blood flow velocity (CBFV) asymmetry, together with a large ICA-to-MCA gradient, were associated with the presence of mismatch. The combined use of 2 TCD parameters (MCA CBFV asymmetry of > or = 30% and ICA-to-MCA gradient > or = 20 cm/sec) had a sensitivity of 75%, specificity of 80%, positive predictive value of 82%, and negative predictive value of 73% at detecting mismatch cases.
  
  
  CONCLUSIONS
  Diffusion-perfusion mismatch appears to be associated with interhemispheric asymmetry between MCA and ICA CBFVs, and a large CBFV gradient between the ICA and MCA on the affected side. Prospective studies are required to verify these observations and to determine whether TCD can be used to follow patients with mismatch.
authors.affiliation: Department of Neurology, Johns Hopkins Hospital, 600 North Wolfe Street, Meyer 5-181, Baltimore, MD 21287-6953, USA. lrestre1@jhmi.edu
authors.forename: Lucas
authors.initials: L
authors.lastname: Restrepo
authors.forename: Alexander Y
authors.initials: AY
authors.lastname: Razumovsky
authors.forename: Wendy
authors.initials: W
authors.lastname: Ziai
authors.forename: Peter B
authors.initials: PB
authors.lastname: Barker
authors.forename: Norman J
authors.initials: NJ
authors.lastname: Beauchamp
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wityk
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001783:Blood Flow Velocity; D004058:Diffusion; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D012680:Sensitivity and Specificity; D020521:Stroke / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D017585:Ultrasonography, Doppler, Transcranial