Rim enhancement in computed tomography with chronic epidural hematoma.

Three cases of epidural hematoma with delayed clinical course are presented. In each patient, computed tomography (CT) initially failed to show typical biconvex, high density extra-axial lesion. The correct diagnosis was reached only after injection of contrast medium revealed enhancement of the border of the hematoma. Importance of contrast enhancement in selected patients with head injury is stress, and the mechanism of rim enhancement is discussed.