Scalp injuries are usually the result of direct impact but may not be apparent in inflicted head injuries. When present, these may manifest as abrasion, bruising, laceration, or a burn; subcutaneous hemorrhage or edema (caput succedaneum); subgaleal hemorrhage or a subperiosteal hemorrhage (cephalhematoma). Although CT is well suited to the evaluation of these fluid collections, MR imaging with its superior soft tissue resolution shows these changes to better advantage (fig 1a & b)
Fig 1. Scout image from a CT exam in an 8-month-old male with suspected NAHI head injury shows biparietal soft tissue swelling (fig 1a .). Coronal T1 gradient echo images (fig 1b) show the biparietal subgaleal hematomas to better advantage.
The prevalence of skull fractures in all cases of abuse is 10% to 13% . The radiographic appearances of skull fractures may be classified into simple and complex categories. CT scan may show a linear defect on axial sections with bone algorithm (fig 2a) however if the fracture is in the plane of the scan it can easily be overlooked. 3D reconstructions are helpful but may obscure the fracture line due to a smoothing effect (fig 2c). Maximum intensity projection images (MIP) are especially sensitive and depict fractures to best advantage (fig 2d).
Fig 2. 8-month-old male with suspected NAHI (same patient as fig 1). Axial nonenhanced CT exam with bone algorithm shows a linear defect (arrow) in the right parietal region (fig 2a) consistent with fracture. A second fracture in the left parietal region (arrow) is less apparent. 3D reconstructed images (fig 2b) depict the right parietal fracture clearly (arrows) however, the left parietal fracture (arrows) is less apparent due to a smoothing effect (fig 2c). MIP images (fig 2d) shows the left parietal fracture to best advantage.