Magnetic resonance imaging of the inner ear and its application to cochlear implant candidates

Magnetic resonance (MR) images of normal and abnormal inner ear obtained with a 1.5 T unit without the use of a surface coil were analyzed to evaluate the effectiveness of this method in the screening of cochlear implant candidates. In a series with sixteen normal adult volunteers, 22 to 45 years in age, 100% of the cochleae, vestibules, and lateral and posterior semicircular canals were clearly demonstrated in T2 weighted images. Satisfactory images were not obtained for 22% of the superior semicircular canals, 22% of the cochlear aqueduct, and 81% of the vestibular aqueduct in axial images, but coronal and sagittal reconstructed images by use of a three-dimensional Fourie transformation sequence provided better detectability of these structures. In five ear surgery patients with proven obliteration of the labyrinth, decreased signal intensity was observed in the T2 weighted images. Ten cochlear implant candidates were examined by MRI prior to implantation, and the results were compared with the surgical findings. In two ears in which the cochlea showed a decrease in signal intensity, the cochlea had been obliterated by inflammatory granulations. On the other hand, the lumens of all nine cochleae which were clearly visualized by MRI were found to be patent. (author)