Enhancing Electrode Location Assessment in Cochlear Implantation via Computed Tomography Image Fusion

This study aimed to determine whether fusing pre- and post-operative computed tomography (CT) images could help in assessing electrode placement and center frequency (CF) in cochlear implant (CI) recipients. A secondary objective was to compare automatic fusion with manual methods for measuring cochlear parameters. The study included twenty ears with CIs that underwent both pre- and post-operative CT scans. Manual measurements of cochlear parameters were initially taken from the post-operative CT images, followed by automatic detection using fused pre- and post-operative CT images with otological software (OTOPLAN). Angular insertion depth (AID) and CF of each electrode contact were calculated using both methods, and error differences were assessed. The analysis showed significant differences between the two methods for cochlear width (B-value) and cochlear duct length (CDL); however, these differences were not clinically significant. Furthermore, there was no statistically significant difference in cochlear diameter (A-value). The mean differences were 0.04 mm for the A-value, 0.21 mm for the B-value, and 0.73 mm for the CDL. The comparison of AID and CF revealed non-significant differences between manual and automatic fusion methods across all electrode contacts, except for electrode number five. According to this study, fusing pre- and post-operative CT images can be used to determine electrode positions in CI recipients. Automatic fused images can potentially measure cochlear parameters, AID, and CF with reduced human interference. Therefore, this method may serve as another basis for creating anatomy-based fitting.