Computed tomography of the intervertebral foramen.

52 cases with pathologic lesions in the intervertebral foramen, studied with CT, are analyzed. The most frequent lesions are intraforaminal disc herniations. These are characterized by their hyperdensity in comparison to the dural sac (34 of 34 cases) and their broad contact with the intervertebral disc space (31 of 34 cases). Foraminal size and contour are usually normal. In contradistinction to disc herniations, benign tumors often show bone erosion of the pressure-type with enlargement of the foramen. Bone infiltration was seen only in malignant lesions and in the single case of Echinococcosis. Preoperative diagnosis of vascular lesions which present with foraminal enlargement is most important for the choice of the appropriate operative approach. Correct CT diagnosis of such vascular lesions is only possible with dynamic CT.