MAGNETIC-RESONANCE-IMAGING OF HYPOXIC-ISCHEMIC BRAIN INJURY IN THE NEONATAL RAT

RATIONALE AND OBJECTIVES. Magnetic resonance (MR) imaging was used for the in vivo evaluation of bihemispheric hypoxic-ischemic (HI) injury in the neonatal rat. METHODS. Seven-day-old rats underwent sham surger y (n = 7) or bilateral carotid artery ligation and hypoxia (30-45 min) (n = 8), T2-weighted imaging was used to study the temporal evolution of injury. Histopathology was used to correlate injury with MR signal changes. RESULTS. T2-weighted images exhibited considerable anatomic detail (0.2 mm resolution in-plane), The cortex, dorsolateral striatum and thalamus were affected, while the hippocampus was spared. Magneti c resonance signal change was seen as early as 1.5 hrs post-HI (lesion extent, 27%-39%), and reached a maximum at 48 hrs (37%-49%). Magnetic resonance imaging estimation of injury at 72 hours after HI was compa red with histopathology and correlated well (r = 0,98), CONCLUSIONS, T he study demonstrates the feasibility of magnetic resonance imaging fo r in vivo evaluation of neonatal brain injury and that vulnerability i n the neonatal hippocampus is strikingly different than in adult HI mo dels.