title: The diffusion-weighted lesion in acute stroke: heterogeneous patterns of flow/metabolism uncoupling as assessed by quantitative positron emission tomography.
abstract: BACKGROUND
  To investigate what the hyperintense lesion in diffusion-weighted imaging (DWI) of acute ischaemic stroke represents metabolically, we prospectively imaged acute carotid-territory stroke patients with DWI along with fully quantitative positron emission tomography (PET), which gives physiological maps of cerebral blood flow (CBF), the cerebral metabolic rate of oxygen (CMRO2) and the oxygen extraction fraction (OEF).
  
  
  METHODS
  Of 10 patients who consented, 5 (3 males, 2 females, 53-84 years, NIHSS 6-16) completed the imaging protocol of back-to-back DWI and PET within 21 (mean 15.7, range 7-21) h of stroke onset. All images were co-registered with the DWI lesion forming a region of interest (ROI) that was transferred to the PET parametric maps (OEF, CBF, CMRO2). Patterns of blood flow and metabolism were assessed within the DWI ROI.
  
  
  RESULTS
  Within the DWI lesions, the following patterns were observed: very low CBF and CMRO2/variable OEF; low CBF/high OEF, and high CBF/low OEF. There was a heterogeneity of patterns between and within DWI lesions. In addition, areas of hyperperfusion (with low OEF) and areas of hypoperfusion (with high OEF) were seen outside the DWI lesions.
  
  
  CONCLUSIONS
  The DWI lesion does not have a single flow/metabolism counterpart, suggesting that it reflects various stages of the ischaemic process.
authors.affiliation: Department of Clinical Neurosciences, University of Cambridge, Cambridge, UK.
authors.forename: Joseph V
authors.initials: JV
authors.lastname: Guadagno
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Warburton
authors.forename: Peter S
authors.initials: PS
authors.lastname: Jones
authors.forename: Tim D
authors.initials: TD
authors.lastname: Fryer
authors.forename: Diana J
authors.initials: DJ
authors.lastname: Day
authors.forename: Jonathan H
authors.initials: JH
authors.lastname: Gillard
authors.forename: T Adrian
authors.initials: TA
authors.lastname: Carpenter
authors.forename: Franklin I
authors.initials: FI
authors.lastname: Aigbirhio
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Price
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Baron
mesh_terms: D000208:Acute Disease; D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000098:blood supply / Q000378:metabolism / Q000473:pathology; D002545:Brain Ischemia / Q000000981:diagnostic imaging / Q000378:metabolism / Q000473:pathology; D002560:Cerebrovascular Circulation; D038524:Diffusion Magnetic Resonance Imaging; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism; D049268:Positron-Emission Tomography; D020521:Stroke / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*
chemical_list: D010100:Oxygen