TEMPORAL AND ANATOMICAL VARIATIONS OF BRAIN WATER APPARENT DIFFUSION-COEFFICIENT IN PERINATAL CEREBRAL HYPOXIC-ISCHEMIC INJURY - RELATIONSHIPS TO CEREBRAL ENERGY-METABOLISM

Cerebral apparent diffusion coefficients (ADCs) were determined in nin e newborn piglets before and for 48 h after transient hypoxia-ischemia . Phosphorus MRS revealed severely reduced cerebral energy metabolism during the insult and an apparently complete recovery 2 h after resusc itation commenced. At this time, mean ADC over the imaging slice (ADC( global)) was 0.88 (0.04) x 10(-9) m(2) . s(-1) (mean (SD)), which was close to the baseline value of 0.92 (0.4) x 10(-9) m(2) . s(-1). In se ven of the animals, a ''secondary'' failure of energy metabolism then evolved, accompanied by a decline in ADC(global) to 0.64 (0.17) x 10(- 9) m(2) . s(-1) at 46 h postresuscitation (P < 0.001 versus baseline). For these seven animals, ADC(global) correlated linearly with the con centration ratio [phosphocreatine (PCr)]/[inorganic phosphate (Pi)] (0 .94 < r < 0.99; P < 0.001). A nonlinear relationship was demonstrated between ADC(global) and the concentration ratio [nucleotide triphospha te (NTP)]/ [Pi + PCr + 3 NTP]. The ADC reduction commenced in the para sagittal cortex before spreading in a characteristic pattern throughou t the brain. ADC seems to be closely related to cerebral energy status and shows considerable potential for the assessment of hypoxic-ischem ic injury in the newborn brain.