Hypoxic Ischemic Encephalopathy.

Hypoxic-ischemic encephalopathy (HIE) is caused by impaired oxygen delivery or inadequate blood flow to the brain that is sustained for a critical duration. Neuroimaging plays a major role in the evaluation of suspected HIE or acute encephalopathy of unclear etiology. MR imaging is the imaging modality of choice, helping estimate the overall acuity, extent, and severity of the injury. This article outlines the basic mechanisms that lead to selective vulnerability in HIE and describes how MRI findings evolve over time.