Proton T2 relaxation of cerebral metabolites during transient global ischemia in rat brain

Putative changes of metabolite T₂ relaxation times were investigated before and after a 20-min period of global ischemia in rat brain in vivo (n= 10) using localized proton MRS at different echo times (2.35 T). Neither absolute T₂ relaxation times (TE = 20-270 ms) nor time courses of T₂-weighted metabolite signals (TE = 135 ms) revealed statistically significant changes during the occlusion or early reperfusion relative to pre-ischemic baseline. These findings are in line with reports of relaxation changes at much later stages and further demonstrate that altered T₂ relaxation is not a confounding factor in diffusion-weighted long-TE proton MRS during early ischemic events.