PROTON T-2 RELAXATION OF CEREBRAL METABOLITES DURING TRANSIENT GLOBAL-ISCHEMIA IN RAT-BRAIN

Putative changes of metabolite T-2 relaxation times were investigated before and after a 20-min period of global ischemia in rat brain in vi vo (n = 10) using localized proton MRS at different echo times (2.35 T ). Neither absolute T,relaxation times (TE = 20-270 ms) nor time cours es of T-2-weighted metabolite signals (TE = 135 ms) revealed statistic ally significant changes during the occlusion or early reperfusion rel ative to pre-ischemic baseline. These findings are in line with report s of relaxation changes at much later stages and further demonstrate t hat altered T-2 relaxation is not a confounding factor in diffusion-we ighted long-TE proton MRS during early ischemic events.