Imaging cochlear implantation with round window insertion in human temporal bones and cochlear morphological variation using high-resolution cone beam CT

Conclusions: The present experimental set-up of high spatial resolution cone-beam computed tomography (CBCT) showed advantages of demonstrating the critical landmarks of the cochlea in identifying the position of intracochlear electrode contacts and has the potential for clinical application in cochlear implant (CI) surgery. Objective: To evaluate a newly developed CBCT system in defining CI electrode array in human temporal bone and cochlear morphological variation. Methods: Standard electrode, flexible tip electrode (Flex28), and an experimental electrode array with 36 contacts from MED-EL were implanted into the cochleae of six human temporal bones through an atraumatic round window membrane insertion. The cochleae were imaged with 900 frames using an experimental set-up based on a CBCT scanner installed with Superior SXR 130-15-0.5 X-ray tube in combination with filtration of copper and aluminum. Results: In all temporal bones, the landmarks of the cochlea, modiolus, osseous spiral lamina, round window niche, and stapes were demonstrated at an average level of 3.4-4.5. The contacts of electrode arrays were clearly shown to locate in the scala tympani. There was a linear correlation between the 'A' value and cochlea height, and between the A value and actual electrode insertion length for the first 360 degrees insertion depth.