DYNAMIC CHANGES IN WATER ADC, ENERGY-METABOLISM, EXTRACELLULAR-SPACE VOLUME, AND TORTUOSITY IN NEONATAL RAT-BRAIN DURING GLOBAL-ISCHEMIA

To obtain a better understanding of the mechanisms underlying early ch anges in the brain water apparent diffusion coefficient (ADC) observed in cerebral ischemia, dynamic changes in the ADC of water and in the energy status were measured at postnatal day 8 or 9 in neonatal rat br ains after cardiac arrest using H-1 MRS/MRI and P-31 MRS, respectively . The time courses of the MR parameters were compared with changes in the extracellular space (ECS) volume fraction (alpha) and tortuosity ( lambda), determined from concentration-time profiles of tetramethylamm onium applied by iontophoresis. The data show a decrease of the ADC of tissue water after induction of global ischemia of which the time cou rse strongly correlates with the time course of the decrease in the EC S volume fraction and the increase in ECS tortuosity. This indicates t hat eel swelling is an important cause for the ADC decrease of water.