DIFFUSION OF METABOLITES IN NORMAL AND ISCHEMIC RAT-BRAIN MEASURED BYLOCALIZED H-1 MRS

The apparent diffusion coefficient (ADC) of choline-containing compoun ds (Cho), creatine and phosphocreatine (Cre), N-acetyl-aspartate (NAA) , lactate, and water was measured in normal rat brain, and in the isch emic and contralateral region of rat brain approximately 3 and 24 h af ter induction of focal cerebral ischemia. After 3 h of ischemia, the A DC of Cre and NAA in the ischemic region had significantly decreased b y 29% and 19%, respectively (P < 0.05). Lactate ADC was also obtained in the ischemic region, After 24 h of focal ischemia, no ADC values co uld be measured for NAA, Cre and Cho in the ischemic region because th eir concentrations had become too low. The ADCs of lactate and water i n the ischemic volume were virtually identical at 3 and 24 h after occ lusion. The experiments suggest that the ADC decrease of water after i nduction of ischemia is partly caused by changes in the diffusion char acteristics of the intracellular compartment.