title: Changes in the proton T2 relaxation times of cerebral water and metabolites during forebrain ischemia in rat at 9.4 T.
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 (approximately 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.
authors.affiliation: Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota Medical School, Minneapolis 55455, USA.
authors.forename: Hao
authors.initials: H
authors.lastname: Lei
authors.forename: Yi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Zhu
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
mesh_terms: D000818:Animals; D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism*; D003401:Creatine / Q000378:metabolism*; D016014:Linear Models; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D016548:Prosencephalon / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014867:Water / Q000378:metabolism
chemical_list: D014867:Water; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine