title: Changes in T1 and T2 observed in brain magnetic resonance imaging with delivery of high concentrations of oxygen.
abstract: OBJECTIVE
  The aim of this study was to clarify the relative contributions of the amount of oxygen in the blood, and vasoconstriction/dilation responsible for changes in T1 and T2 observed in brain during hyperoxia.
  
  
  METHODS
  T1 and T2 values of the cerebral cortex and pituitary gland in mice were determined in room air. After room air was changed to either 100% oxygen (n = 8) or carbogen (n = 8), T1 and T2 values were again determined. Changes in each value with both gases were compared.
  
  
  RESULTS
  In both challenges, T1 values of the cerebral cortex decreased, whereas significant T2 prolongation of the cerebral cortex and pituitary gland was demonstrated. However, both cortex and pituitary gland displayed similar responses in T1 and T2 values when exposed to 100% oxygen or carbogen.
  
  
  CONCLUSIONS
  Reduction of T1 was introduced by the increased amount of dissolved oxygen in blood, and the increased fraction of oxyhemoglobin caused T2 prolongation. The contribution of vasoconstriction/dilation by carbogen to changes in T1 and T2 may be negligible.
authors: Department of Radiology, University of Fukui, Fukui, Japan. uematsu@fmsrsa.fukui-med.ac.jp
authors: Hidemasa
authors: H
authors: Uematsu
authors: Masaya
authors: M
authors: Takahashi
authors: Hiroto
authors: H
authors: Hatabu
authors: Chih-Liang
authors: CL
authors: Chin
authors: Suzanne L
authors: SL
authors: Wehrli
authors: Felix W
authors: FW
authors: Wehrli
authors: Toshio
authors: T
authors: Asakura
mesh_terms: D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002540:Cerebral Cortex / Q000098:blood supply*; D000860:Hypoxia / Q000097:blood*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D010100:Oxygen / Q000097:blood*; D010902:Pituitary Gland / Q000098:blood supply*; D014661:Vasoconstriction; D014664:Vasodilation
chemical_list: D002245:Carbon Dioxide; C011700:carbogen; D010100:Oxygen