Evolution of the diffusion-weighted signal and the apparent diffusion coefficient in the late phase after minor stroke: a follow-up study

J Neurol. 2007 Mar;254(3):375-83. doi: 10.1007/s00415-006-0381-y. Epub 2007 Mar 7.


Introduction: Diffusion-weighted imaging (DWI) is mainly used in acute stroke, and signal evolution in the acute phase has been studied extensively. However, patients with a minor stroke frequently present late. Recent studies suggest that DWI may be helpful at this stage, but only very few published data exist on the evolution of the DW-signal in the weeks and months after a stroke. We performed a follow-up study of DWI in the late stages after a minor stroke.

Methods: 28 patients who presented 48 hours to 14 days after a minor stroke underwent serial MRI at baseline, 4 weeks, 8 weeks, 12 weeks, 6 months and>or=9 months after their event. Signal intensity within the lesion was determined on T2-weighted images, DW-images and the Apparent Diffusion Coefficient (ADC) map at each time-point, and ratios were calculated with contralateral normal values (T2r, DWIr, ADCr).

Results: T2r was increased in all patients from the beginning, and showed no clear temporal evolution. ADCr normalized within 8 weeks in 83% of patients, but still continued to increase for up to 6 months after the event. The DW-signal decreased over time, but was still elevated in 6 patients after>or=6 months. The evolution of ADCr and DWIr showed statistically highly significant inter-individual variation (p<0.0001), which was not accounted for by age, sex, infarct size or infarct location.

Conclusion: The ADC and the DW-signal may continue to evolve for several months after a minor ischaemic stroke. Signal evolution is highly variable between individuals. Further studies are required to determine which factors influence the evolution of the ADC and the DW-signal.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Mapping*
  • Diffusion Magnetic Resonance Imaging*
  • Disease Progression
  • Echo-Planar Imaging*
  • Female
  • Follow-Up Studies
  • Humans
  • Image Processing, Computer-Assisted / methods
  • Male
  • Middle Aged
  • Stroke / diagnosis*
  • Time Factors