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 language | English (US) |
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Pages (from-to) | 979-984 |
Number of pages | 6 |
Journal | Magnetic resonance in medicine |
Volume | 49 |
Issue number | 6 |
DOIs | |
State | Published - Jun 1 2003 |
Keywords
- BOLD
- Cerebral metabolite
- Forebrain ischemia
- Magnetic resonance spectroscopy
- Rat
- T relaxation time