Abstract:
Neonatal hypoxic-ischemic encephalopathy (HIE) is a common type of severe brain injury in the perinatal period and an important cause of neonatal death and long-term neurodevelopmental impairment. Even among infants who survive the acute phase, some may still develop cerebral palsy, epilepsy, and impairments in cognition, language, behavior and learning ability. Early identification of the extent of brain injury and assessment of prognostic risk are of great importance for clinical treatment, rehabilitation intervention and long-term follow-up. Magnetic resonance imaging (MRI) can demonstrate the location, extent and evolution of brain injury, and can also reflect changes in brain tissue diffusion, metabolism, perfusion and function, making it an important imaging modality for the evaluation of HIE. Different patterns of brain injury are associated with neurodevelopmental outcomes to varying degrees. White matter/watershed injury is associated with long-term abnormalities in cognition, language and learning ability. Involvement of the basal ganglia-thalamus and posterior limb of the internal capsule is closely associated with cerebral palsy and motor dysfunction, and extensive global brain injury suggests a higher risk of death and severe neurodevelopmental impairment. Diffusion restriction and decreased apparent diffusion coefficient values during the acute phase can reflect injury burden, although their interpretation is affected by the timing of MRI examination. On magnetic resonance spectroscopy, decreased thalamic N-acetylaspartate (NAA) and increased lactate/NAA ratio have certain predictive value for severe adverse outcomes. This review focuses on the prognostic significance and scope of application of different MRI findings, in conjunction with clinical challenges such as mild HIE, mixed patterns of brain injury and long-term cognitive dysfunction. It also discusses the value of imaging assessment in prognostic risk stratification.