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Keywords:

  • hypoxia-ischemia;
  • apparent diffusion coefficient;
  • neonatal brain;
  • energy metabolism

Abstract

Cerebral apparent diffusion coefficients {ADCs) were determined in nine 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 resuscitation commenced. At this time, mean ADC over the imaging slice (ADCglobal) was 0.88 (0.04) × 10[BOND]9 m2 · s[BOND]1 (mean (SD}), which was close to the baseline value of 0.92 (0.4) × 10[BOND]9 m2 · s[BOND]1. In seven of the animals, a “secondary” failure of energy metabolism then evolved, accompanied by a decline in ADCglobal to 0.64 (0.17) × 10[BOND]9 m2 · s[BOND]1 at 46 h postresuscitation (P < 0.001 versus baseline). For these seven animals, ADCglobal correlated linearly with the concentration ratio [phosphocreatine (PCr)][inorganic phosphate (Pi)] (0.94 r < 0.99; P > 0.001). A nonlinear relationship was demonstrated between ADCglobal, and the concentration ratio [nucleotide triphosphate (NTP)]/ [Pi + PCr + 3 NTP]. The ADC reduction commenced in the parasagittal cortex before spreading in a characteristic pattern throughout the brain. ADC seems to be closely related to cerebral energy status and shows considerable potential for the assessment of hypoxic-ischemic injury in the newborn brain.