Linear fractures invisible on routine axial computed tomography: a pitfall at radiological screening for minor head injury.

Computed tomography (CT) is now widely used as the only screening method for fractures in patients with head injury. However, clear depiction of a fracture requires a discontinuity in the skull, so linear fractures parallel to the CT slice may not be visualized. We retrospectively evaluated 302 patients with minor head injuries aged from 0 to 91 years, who had undergone routine skull radiography (anteroposterior and lateral views) and head CT to study these types of fracture and discuss the risk of nondetection. Three patients had linear fractures (0.99%) that were invisible on bone window axial CT but detected on skull radiography, which all ran parallel to the scan slice. Two patients developed acute epidural hematoma or traumatic subarachnoid hemorrhage. Evaluation of head injury by only axial CT may miss such fractures and result in sequelae, so diagnosticians should be alert to the possible presence of this type of fracture.