Normal and diseased acoustic pathway: evaluation with MR imaging.

To evaluate the use of magnetic resonance (MR) imaging in the assessment of the normal and diseased acoustic pathway, 176 patients with sensorineural hearing loss (SNHL) underwent MR imaging. In 65 patients an abnormality was detected at MR; in 50 of the 65, the abnormality was believed to be definitely or possibly responsible for the SNHL. In 47% of cases, the cochlea (3%) or vestibulocochlear nerve (44%) was involved by primary lesions. Computed tomography (CT) was performed, in addition to MR, in 25 patients in whom an abnormality was seen at MR; in 18 (72%), MR was believed to be superior to CT for lesion display. A review of 30 normal MR images of the cerebellopontine angle and brain disclosed that the cochlea was directly imaged in all cases with the use of short or long repetition times (TRs). The vestibulocochlear nerve was directly seen in 77% of cases with the use of short TR imaging. In conclusion, MR imaging delineates the acoustic pathway more clearly than does CT and is recommended for the examination of abnormalities in this region.