CT EVALUATION OF PERINEURAL ORBITAL LESIONS - EVALUATION OF THE TRAM-TRACK SIGN

Abstract

Cranial computed tomographic scans of 225 patients with orbital mass lesions were reviewed. In 11 patients, the optic nerve was seen as a linear defect through the orbital mass. These 11 cases comprised 3 optic nerve sheath meningiomas, 3 hemangiomas, 2 cases of pseudotumor and 1 case each of Erdheim-Chester disease, optic neuritis and metastatic disease. Optic nerve sheath meningiomas could be further differentiated from the other mass lesions by showing the entire length of the optic nerve through the lesion, smooth margins, a fusiform shape and parallel enhancement of the periphery of the optic nerve even greater that that of the surrounding mass. These features may aid in differentiating optic nerve sheath meningiomas from other mass lesions in the orbit.