Computed tomography and/or magnetic resonance imaging before pediatric cochlear implantation? Developing an investigative strategy

Objective: To investigate and compare the usefulness of preoperative magnetic resonance (MR) imaging and high-resolution temporal bone computed tomography (HRCT) in pediatric cochlear implant candidates. Study Design: Prospective. Setting: Tertiary referral center. Patients: A cohort of 92 pediatric patients with profound hearing. Inclusion criteria were MR, computed tomography, and cochlear implantation. Intervention. Diagnostic: All patients had preoperative imaging of the petrous temporal bone (HRCT, T2-weighted fast spin echo, axial 3D Fast Imaging Employing Steady-state Acquisition [FIESTA] MR) and brain (Fast Fluid-attenuated Inversion-recovery [FLAIR] MR). Main Outcome Measure(s): Overall prevalence of inner ear dysplasias in this population and comparison of detection rates between HRCT, T2 Fast Spin Echo (FSE), and FIESTA MR sequences. Results: Radiological abnormalities were observed in 32 and 59% of MR and HRCT temporal bone, respectively. Synchronous intracranial findings were noted in 40% on brain MR. Common vestibulocochlear nerve was observed in 3% ears and directed side of implantation. Consistent discrepancies noted on HRCT were inability to diagnose early obliterative labyrinthitis and presence of the cochlear nerve in the internal auditory canal. With respect to MR, enlarged vestibular aqueducts and narrow cochlear nerve canals were consistently under identified. Conclusion: Dual-modality imaging with HRCT and MR of petrous bone and MR brain in the precochlear implant pediatric population detects abnormalities related to deafness, which would not otherwise be found using either modality alone. There is overlap between the imaging modalities in the type of abnormalities detected, and we present a case for selective use of HRCT within a diagnostic algorithm, using the patient risk factors we have identified.