Surface-coil magnetic resonance imaging of the internal auditory canal.

Computed tomography is effective for detecting acoustic neuromas, but not for resolving individual nerves in the internal auditory canal. Surface-coil magnetic resonance (MR) images of the internal auditory canal were obtained using a 1.5 T superconducting magnet, a 13.5-cm-diameter surface coil, 3- and 5-mm-thick slices, and partial-saturation pulse sequences. Cranial nerves VII and VIII (three branches) were identified on MR images in volunteers and on corresponding cryomicrotomic sections. The nerves were obscured in one patient with an acoustic neuroma. Because high-resolution surface-coil images can demonstrate specific nerves in the internal auditory canal, MR should be a sensitive study to evaluate cranial nerves VII and VIII in patients with facial paralysis and neurosensory hearing loss that is congenital or caused by small acoustic neuromas.