Clinical significance of T1-weighted MR images following transient cerebral ischemia

J Neurol Sci. 2006 Feb 15;241(1-2):19-24. doi: 10.1016/j.jns.2005.10.013. Epub 2006 Jan 4.


To try to determine the cause of hyperintensity of T1-weighted MR images that occurred on and after day 7 following transient cerebral ischemia, dynamic changes in T1-weighted images and histology of rats subjected to 20 min of 4-vessel occlusion were observed. T1-weighted images showed no remarkable alteration on days 1 and 3, although high signal intensity in the striatal region, in which the T1 value was significantly lower than the values on days 1 and 3, was observed on day 7. High signal intensity in T1-weighted images indicates low T1 values. Histological observation revealed accumulation of microglia in the striatal region on day 7 by lectin staining. There was a tight correlation between T1 values and number of lectin-positive cells. Microglia had stout processes and hypertrophic cell bodies on day 7, resembling lipid-laden phagocytes. Sudan black B staining showed the presence of many fatty droplets in the striatal region on day 7. Furthermore, double staining with lectin and Sudan black B revealed the presence of fatty droplets in bodies of lectin-positive cells on day 7. These results suggest that hyperintensity of T1-weighted images on day 7 following transient ischemia and reperfusion indicates accumulation and phagocytic activation of microglia. T1-weighted images seem to represent the progression of non-reversible tissue injury after transient ischemia and reperfusion.

Publication types

  • Comparative Study

MeSH terms

  • Animals
  • Azo Compounds
  • Cell Count / methods
  • Disease Models, Animal
  • Ischemic Attack, Transient / pathology*
  • Lectins
  • Linear Models
  • Magnetic Resonance Imaging / methods*
  • Male
  • Naphthalenes
  • Rats
  • Rats, Wistar
  • Time Factors


  • Azo Compounds
  • Lectins
  • Naphthalenes
  • Sudan Black B