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

✍ Scribed by Hao Lei; Yi Zhang; Xiao-Hong Zhu; Wei Chen

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 236 KB
• Volume: 49
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.10490

✦ Synopsis

Abstract

Proton T~2~ 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 (^1^H‐MRS) with Hahn echoes formed at different echo times (TEs). It was found that the T~2~ values of water and N‐acetyl aspartate (NAA) methyl, but not total creatine (tCr) methyl, decrease significantly (∼10%) during ischemia, and this T~2~ reduction is reversed by reperfusion. The T~2~ 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 T~2~ changes for tCr can probably be explained by the fact that the BOLD‐related T~2~ decrease was counterbalanced by the conversion of phosphocreatine (PCr) to creatine (Cr), which has a longer T~2~ than PCr, during ischemia. The changes in T~2~ should be taken into account for the quantification of metabolite concentrations during ischemia. Magn Reson Med 49:979–984, 2003. © 2003 Wiley‐Liss, Inc.