Radiologic evaluation of the cerebellopontine cistern and the internal auditory canal.

Radiologic evaluation of patients with unilateral sensorineural hearing loss depends on the quality of the computed tomographic (CT) scanner. Two scanners were evaluated in the present study: one utilizing thick collimation (10- and 13-mm sections) and the second utilizing thin collimation (1.5-mm sections). In both evaluations, intravenous contrast medium was used to exclude a cerebellopontine angle mass. If the cerebellopontine cistern is normal and there is clinical evidence of an intracanalicular lesion, air or metrizamide CT is used. When 10- and 13-mm sections are used, air provides the best contrast with overlapping sections. When 1.5-mm sections are used, coronal CT shows metrizamide in the internal auditory canal.