Changes in the proton T2 relaxation times of cerebral water and metabolites during forebrain ischemia in rat at 9.4 T

Hao Lei, Yi Zhang, Xiao-Hong Zhu, Wei Chen

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26 Scopus citations

Abstract

Proton T2 relaxation times of cerebral water and metabolites were measured before, during, and after transient forebrain ischemia in rat at 9.4 T using localized proton magnetic resonance spectroscopy (1H-MRS) with Hahn echoes formed at different echo times (TEs). It was found that the T2 values of water and N-acetyl aspartate (NAA) methyl, but not total creatine (tCr) methyl, decrease significantly (∼10%) during ischemia, and this T2 reduction is reversed by reperfusion. The T2 reduction observed for NAA was most likely caused by the extravascular component of the blood oxygenation level-dependent (BOLD) effect induced by a drastically increased deoxyhemoglobin content during ischemia. The absence of T2 changes for tCr can probably be explained by the fact that the BOLD-related T2 decrease was counterbalanced by the conversion of phosphocreatine (PCr) to creatine (Cr), which has a longer T2 than PCr, during ischemia. The changes in T2 should be taken into account for the quantification of metabolite concentrations during ischemia.

Original languageEnglish (US)
Pages (from-to)979-984
Number of pages6
JournalMagnetic resonance in medicine
Volume49
Issue number6
DOIs
StatePublished - Jun 1 2003

Keywords

  • BOLD
  • Cerebral metabolite
  • Forebrain ischemia
  • Magnetic resonance spectroscopy
  • Rat
  • T relaxation time

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