Hypoxic Ischemic Brain Injury

This is patient had a cardiac arrest and this is the MRI brain, DWI images. Hypoxic injury in adults is more often a result of cardiac arrest or cerebrovascular disease. 

Background- Hypoxic injury primarily affects the gray matter structures: the basal ganglia, thalami, cerebral cortex (in particular the sensorimotor and visual cortices, although involvement is often diffuse), cerebellum, and hippocampi. 

Reasoning- This predominance of gray matter injury is related to the fact that gray matter contains most of the dendrites where postsynaptic glutamate receptors are located and are, therefore, the sites most susceptible to the effects of glutamate excitotoxicity. As a result of synaptic activity, gray matter is also more metabolically active than white matter. 

Radiological Findings- Diffusion-weighted MR imaging is the earliest imaging modality to become positive, usually within the first few hours after a hypoxic-ischemic event. During the first 24 hours, diffusion-weighted imaging may demonstrate increased signal intensity in the cerebellar hemispheres, basal ganglia, or cerebral cortex (in particular, the perirolandic and occipital cortices)