title: Clinical significance of T1-weighted MR images following transient cerebral ischemia.
abstract: 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.
authors.affiliation: Department of Anesthesiology and Resuscitology, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama City, Okayama, 700-8558, Japan.
authors.forename: Hisami
authors.initials: H
authors.lastname: Aoe
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Takeda
authors.forename: Hidero
authors.initials: H
authors.lastname: Kawahara
authors.forename: Akio
authors.initials: A
authors.lastname: Tanaka
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Morita
mesh_terms: D000818:Animals; D001391:Azo Compounds; D002452:Cell Count / Q000379:methods; D004195:Disease Models, Animal; D002546:Ischemic Attack, Transient / Q000473:pathology*; D037102:Lectins; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009281:Naphthalenes; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
chemical_list: D001391:Azo Compounds; D037102:Lectins; D009281:Naphthalenes; C016118:Sudan Black B