Abstract
The author investigated high-resolution MR imaging (MRI) of the inner ear and evaluated its usefulness in the selection of patients for cochlear implants. MRI was performed with a 1.5T unit with the use of the head coil. The minimum thickness of the sections was 2.5mm. T1-and T2-weighted images were obtained. The matrix size was 256×256, and the field of view was 15cm. ECG-gating was introduced to eliminate motion artifacts.
T2-weighted images could clearly delineate details of liquid containing labyrinth structures, including the cochlea, the vestible, the semicircular canals, and the internal auditory canal. With the proper use of T1 and T2 sequences, tissue characterization between lymph fluid and soft tissue could be obtained. This point was considered to be one of the greatest advantages of MRI over high-resolution CT in the diagnosis of inner ear disorders. The head coil technique seems to be superior to the surface coil technique in that it can generate homogeneous signal intensity, and therefore visual comparison of cochlea signals of both sides is possible under the same conditions.
The author concluded that high-resolution MRI of the inner ear is useful for the preoperative assessment of cochlear implant candidates in order to rule out soft tissue occlusion of the cochlea, which cannot be diagnosed even by high-resolution CT.
