[Brain and head injury. Part 1: Clinical classification, imaging modalities, extra-axial injuries, and contusions].

This article describes the imaging tools for efficient diagnostic management of head trauma victims. The basic mechanisms of brain injuries are explained and the imaging features are described. Computed tomography remains the most important method for the initial screening and follow-up investigation. Though magnetic resonance imaging has a higher sensitivity to most traumatic lesions, it does not play an important role in the acute phase of head trauma patients. In the first part of this paper clinical classifications, imaging modalities, extra-axial injuries, and contusions are described. In the second part of this paper intra-axial and secondary injuries are discussed.