title: Water diffusion compartmentation at high b values in ischemic human brain.
abstract: OBJECTIVE
  We studied the evolution of brain water compartments during the early stage of ischemic stroke.
  
  
  METHODS
  Diffusion-weighted imaging was performed at 1.5 T in 10 volunteers and 14 patients with stroke. We used a single-shot echo-planar technique with 11 b values of 0-5000 s/mm(2). Regions of interest were selected in the white matter (WM) and striatum of the volunteers and in the ischemic core of the patients. Measurements were fitted on the basis of a biexponential decay with the b factor as follows: S(b) = S(0)[(f(slow) x exp(-b x ADC(slow)) + (f(fast) x exp(-b x ADC(fast))] where S(b) is the signal intensity in the presence of a diffusion gradient, S(0) is the signal intensity without diffusion sensitization, ADC(slow) and ADC(fast) are the respective apparent diffusion coefficients (ADCs) of slow diffusing compartments (SDCs) and fast diffusing compartments (FDCs), and f(slow) and f(fast) the respective contributions to the signal intensity of SDC and FDC.
  
  
  RESULTS
  In healthy subjects, FDC represents 74.3 +/- 3.1% of brain water, with ADC(fast) = (124.6 +/- 12.0) x 10(-5) mm(2)/s and ADC(slow) = (15.5 +/- 3.9) x 10(-5) mm(2)/s. In stroke, decreased FDC (49.1% +/- 10.9%; P = 1.05 x10(-5)) and increased ADC(slow) ([22.4 +/- 8.1] x 10(-5) mm(2)/s; P = 8.07 x 10(-3)) were observed, but ADC(fast) was not significantly changed ([135.6 +/- 25.7] x 10 (-5) mm(2)/s; P =.151).
  
  
  CONCLUSIONS
  The restricted diffusion observed in the early stroke is mainly related to a redistribution of water from the FDC to the SDC.
authors.affiliation: Department of Neuroradiology, Henri Mondor Hospital, Tassigny, Créteil, France.
authors.forename: Pierre
authors.initials: P
authors.lastname: Brugières
authors.forename: Philippe
authors.initials: P
authors.lastname: Thomas
authors.forename: Anne
authors.initials: A
authors.lastname: Maraval
authors.forename: Hassan
authors.initials: H
authors.lastname: Hosseini
authors.forename: Catherine
authors.initials: C
authors.lastname: Combes
authors.forename: Abdallah
authors.initials: A
authors.lastname: Chafiq
authors.forename: Lucile
authors.initials: L
authors.lastname: Ruel
authors.forename: Stéphane
authors.initials: S
authors.lastname: Breil
authors.forename: Marc
authors.initials: M
authors.lastname: Peschanski
authors.forename: André
authors.initials: A
authors.lastname: Gaston
mesh_terms: D001834:Body Water / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism*; D038524:Diffusion Magnetic Resonance Imaging; D006801:Humans; D020521:Stroke / Q000378:metabolism*