title: Longitudinal diffusion tensor and manganese-enhanced MRI detect delayed cerebral gray and white matter injury after hypoxia-ischemia and hyperoxia.
abstract: BACKGROUND
  Hypoxia-ischemia (HI) induces delayed inflammation and long-term gray and white matter brain injury that may be altered by hyperoxia.
  
  
  METHODS
  HI and 2 h of hyperoxia (100% O2) or room air (21% O2) in 7-d-old (P7) rats were studied by magnetic resonance imaging at 7 Tesla during 42 d: apparent diffusion coefficient (ADC) maps on day 1; T(1)-weighted manganese-enhanced images on day 7; diffusion tensor images on days 21 and 42; and T2 maps at all time points.
  
  
  RESULTS
  The long-term brain tissue destruction on T2 maps was more severe in HI+hyperoxia than HI+room air. ADC was lower in HI+hyperoxia vs. HI+room air and sham and was correlated with long-term outcome. Manganese enhancement indicating inflammation was seen in both the groups along with more microglial activation in HI+hyperoxia on day 7. Fractional anisotropy (FA) in corpus callosum was lower and radial diffusivity was higher in HI+hyperoxia than that in HI+room air and sham on day 21. From day 21 to day 42, FA and radial diffusivity in HI+hyperoxia were unchanged, whereas in HI+room air, FA increased and radial diffusivity decreased to values similar to sham.
  
  
  CONCLUSIONS
  Hyperoxia caused a more severe tissue destruction, delayed irreversible white matter injury, and increased inflammatory response resulting in a worsening in the trajectory of injury after HI in developing gray and white matter.
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, Norwegian University of Science and Technology (NTNU), Trondheim, Norway. tora.s.morken@ntnu.no
authors.forename: Tora Sund
authors.initials: TS
authors.lastname: Morken
authors.forename: Marius
authors.initials: M
authors.lastname: Widerøe
authors.forename: Christina
authors.initials: C
authors.lastname: Vogt
authors.forename: Stian
authors.initials: S
authors.lastname: Lydersen
authors.forename: Marianne
authors.initials: M
authors.lastname: Havnes
authors.forename: Jon
authors.initials: J
authors.lastname: Skranes
authors.forename: Pål Erik
authors.initials: PE
authors.lastname: Goa
authors.forename: Ann-Mari
authors.initials: AM
authors.lastname: Brubakk
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology*; D054022:Cerebrum / Q000473:pathology; D002712:Chlorides; D003287:Contrast Media; D003337:Corpus Callosum / Q000473:pathology; D056324:Diffusion Tensor Imaging; D004195:Disease Models, Animal; D018496:Hyperoxia / Q000150:complications / Q000473:pathology*; D020925:Hypoxia-Ischemia, Brain / Q000150:complications / Q000473:pathology*; D056784:Leukoencephalopathies / Q000209:etiology / Q000473:pathology*; D017895:Manganese Compounds; D051381:Rats; D017208:Rats, Wistar; D012720:Severity of Illness Index; D013997:Time Factors
chemical_list: D002712:Chlorides; D003287:Contrast Media; D017895:Manganese Compounds; C025340:manganese chloride