Elevations of diffusion anisotropy are associated with hyper-acute stroke: a serial imaging study

Magn Reson Imaging. 2008 Jun;26(5):683-93. doi: 10.1016/j.mri.2008.01.015. Epub 2008 Apr 28.


Diffusion tensor imaging (DTI) studies of human ischemic stroke within 24 h of symptom onset have reported variable findings of changes in diffusion anisotropy. Serial DTI within 24 h may clarify these heterogeneous results. We characterized longitudinal changes of diffusion anisotropy by analyzing discrete ischemic white matter (WM) and gray matter (GM) regions during the hyperacute (2.5-7 h) and acute (21.5-29 h) scanning phases of ischemic stroke onset in 13 patients. Mean diffusivity (MD), fractional anisotropy (FA) and T2-weighted signal intensity were measured for deep and subcortical WM and deep and cortical GM areas in lesions outlined by a > or =30% decrease in MD. Average reductions of approximately 40% in relative (r) MD were observed in all four brain regions during both the hyperacute and acute phases post stroke. Overall, 9 of 13 patients within 7 h post symptom onset showed elevated FA in at least one of the four tissues, and within the same cohort, 11 of 13 patients showed reduced FA in at least one of the ischemic WM and GM regions at 21.5-29 h after stroke. The fractional anisotropy in the lesion relative to the contralateral side (rFA, mean+/-S.D.) was significantly elevated in some patients in the deep WM (1.10+/-0.11, n=4), subcortical WM (1.13+/-0.14, n=4), deep GM (1.07+/-0.06, n=1) and cortical GM (1.22+/-0.13, n=5) hyperacutely (< or =7 h); however, reductions of rFA at approximately 24 h post stroke were more consistent (rFA= 0.85+/-0.12).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acute Disease
  • Aged
  • Anisotropy
  • Brain Ischemia / pathology*
  • Contrast Media
  • Diffusion Magnetic Resonance Imaging / methods*
  • Female
  • Gadolinium
  • Humans
  • Image Processing, Computer-Assisted
  • Male
  • Stroke / pathology*
  • Time Factors


  • Contrast Media
  • Gadolinium