Traumatic axonal injury is among the most severe types of traumatic brain injury, sometimes leading to persistent vegetative states despite mild-appearing imaging findings.
o Mechanism + classic locations of DAI: shearing injury due to different soft tissue densities (gray-white junction) and parenchymal fixation (splenium of corpus callosum and dorsolateral midbrain).
o GRE sequence often reveals tiny microhemorrhages, invisible on CT.
Contusion is a bruise of the brain surface and, by definition, involves the cortex.
o Classic locations: anterior/inferior frontal and temporal lobes (abutting the rough anterior skull base)
o In ambiguous cases, a follow-up CT may show interval blooming of the contusion with edema and hemorrhage.