Magnetic resonance imaging (MRI) as a translational tool for the study of neonatal stroke.

More than half of neonatal stroke survivors have long-term sequelae, including seizures and neurological deficits. Although the immature brain has tremendous potential for recovery, mechanisms governing repair are essentially unexplored. We investigated whether magnetic resonance imaging (MRI) early or late after transient middle cerebral arterial occlusion in postnatal day (P) 10 rats can serve as an intermediate endpoint for long-term studies. Injured animals selected by diffusion-weighted MRI during middle cerebral arterial occlusion were scanned using T2-weighted MRI at P18 and P25 (injury volumes on MRI and histology were compared) or were subjected to contrast-enhanced MRI at P13 to characterize cerebral microcirculatory disturbances and blood-brain barrier leakage. Injury volume during middle cerebral artery occlusion did not predict histological outcome at 2 weeks. Major reductions in injury volume occurred by P18, with no further changes by P25 and correlated with histological injury. Cerebral perfusion was significantly reduced in the injured caudate but blood-brain barrier leakage was small. Therefore, conventional T2-weighted MRI performed during a subchronic injury phase predicts a long-term histological outcome after experimental neonatal focal stroke.