Patterns of skull base fracture: a three-dimensional computed tomographic study.

Three-dimensional (3D) computed tomographic (CT) reconstructions were studied retrospectively in 14 patients with skull base fractures. Our aim was to assess the clarity of visualisation and pattern of these fractures. The reformations were obtained from 3 mm thick two-dimensional (2D) CT images. The 2D data stored on optical discs were retrieved and reformatted using the scanner's software. The 3D technique could demonstrate the presence of fractures as well as 2D images. It was of special value in defining the depth and extent of fractures in the floor of the cranial fossae. Undisplaced and displaced fractures could both be demonstrated. Fractures in the anterior fossa run diagonally towards the midline and then cross the cribriform plate of the ethmoid bone. Fractures of the middle fossa run obliquely anteroposterior. Fractures in the lamina papyracea and cribriform plate were difficult to reconstruct due to the thinness of these bones and threshold definitions. The volume of the 3D block determines the angles suitable for viewing the fractures. In spite of present technical difficulties, the 3D images are of greater anatomical and diagnostic value, particularly in anterior fossa fractures. There is no additional radiation risk to the patient, since reconstructions are made from routine 2D images.