Shear injuries are most often multiple, ovoid and parallel to white matter fiber bundles. They are hyperintense on T2 and hypointense of T1-weighted scans, unless hemorrhagic components are present, in which case more complex patterns are observed. During transition phases of hematoma evolution, combinations of methemoglobin, hemosiderin rings and peripheral edema can result in layers of differing signal intensity and a target-like appearance. The axial plane is the primary plane of imaging for both cortical contusions and shear injuries, but supplemental coronal views are helpful to assess injuries to the body of the corpus callosum and the inferior frontal and temporal lobes. Fast scan techniques or gradient-echo images have lower resolution but are useful in uncooperative patients.
Contrast enhancement has little role in the evaluation of brain contusions.
Unfortunately, there are over a million cases of child abuse in the United States each year. Intracranial injuries may be the result of either direct blows to the head, shaking, whiplash, or strangulation. The presence of an inner hemispheric subdural hematoma is often a tip-off of underlying abuse as it results usually from a whiplash type of injury rather than from a direct blow. There may also be associated subarachnoid hemorrhage as well as subdural hematomas or even subdural hygromas of different ages. One should also be alert for possible underlying non-accidental trauma in the presence of multiple fractures often of different ages.