Abstract
Background
The selection of an appropriate imaging technique for assessment before cochlear implantation is critical for precise diagnosis and management. While magnetic resonance imaging (MRI) is used for the diagnosis of several conditions, such as labyrinthitis ossificans, cochlear nerve deficiency, and neoplasms, high-resolution computed tomography (HRCT) provides excellent details of the temporal bone. However, it remains unclear whether routine MRI provides any additional benefits over HRCT.
Objectives
To assess the added value of MRI as a screening tool for temporal bone abnormalities in cochlear implant candidates through comparisons of its findings with those of HRCT.
Materials and method
It is a retrospective analysis of preoperative HRCT and MR images in a tertiary referral center. A total of 308 patients who underwent MRI and HRCT examinations before cochlear implantation between 2013 and 2015 were included. Preoperative HRCT and MR images were screened for temporal bone abnormalities by a senior neurotologist and a neuroradiologist.
Results
HRCT detected inner ear deformities in 51 of the 308 (16.6%) subjects, whereas MRI revealed abnormalities in only 18 (5.8%) of subjects. HRCT detected the same inner abnormalities in 16 of the 18 (88.9%) subjects diagnosed by MRI, whereas it showed normal results for the remaining two subjects. MRI detected cochlear nerve aplasia/hypoplasia in 13 subjects, 11 of whom had associated inner ear deformities that were detected by HRCT. The MR images of nine subjects showed cochlear fibrosis, which was confirmed by HRCT in all nine subjects.
Conclusion
In this study, MRI did not exhibit significant additional benefits over HRCT, and its routine use for the preoperative assessment of CI candidates was not justified. However, MRI is warranted for subjects at an increased risk of cochlear nerve aplasia due to an inner ear deformity or a narrow internal auditory canal. The establishment of criteria that facilitate the performance of MRI only when absolutely needed will reduce healthcare costs, prevent unnecessary exposure to the risks associated with general anesthesia, and shorten delays before cochlear implantation.