High-resolution cone-beam computed tomography: a potential tool to improve atraumatic electrode design and position.

CONCLUSIONS: Flat-panel cone-beam computed tomography (CBCT) is able to assess the trajectory of the implanted cochlear implant (CI) array. This is essential to determine specific effects of electrode design and surgical innovations on outcomes in cochlear implantation. CBCT is a non-invasive approach yielding similar data to histopathological analyses, with encouraging potential for use in surgical, clinical and research settings. OBJECTIVES: To examine the fidelity of CBCT imaging and custom 3D visualization in characterizing CI insertion in comparison to gold standard, histopathological examination. METHODS: Eleven human temporal bones were implanted with the 'Straight Research Array' (SRA). Post-insertion, they were imaged with a prototype mobile C-arm for intraoperative CBCT. Post-acquisition processing of low-dose CBCT images produced high-resolution 3D volumes with sub-millimetre spatial resolution (isotropic 0.2 mm(3) voxels). The bones were resin impregnated and sectioned for light microscopic examination. Dimensional electrode characteristics visible in section images were compared with corresponding CBCT images by independent observers. RESULTS: Overall, CBCT demonstrated adequate resolution to detect: 1) scala implanted; 2) kinking; 3) number of intracochlear contacts; 4) appropriate ascension of the array; and overall confirms ideal insertion. CBCT did not demonstrate adequate resolution to detect reversal of electrode contacts or basilar membrane rupture.

Radiation therapy in cochlear implant recipients.

HYPOTHESIS: Processes of scattering and attenuation were investigated to determine the consequence on dose distributions by having a cochlear implant in the field of therapeutic radiation. BACKGROUND: Radiation oncology medical accelerator beams of 6- and 18-MV x-ray energy were used. Five cochlear implants were investigated. METHODS: Each implant model was individually studied using computer dose modeling and through exercises in radiation measurement during live delivery. RESULTS: No side scatter was detected, and negligible backscattering was observed for the primary device housing and electrodes. Attenuation consequences were found to be dependent on the model of cochlear implant studied and specifically dependent on the material composition of each device. CONCLUSION: The maximum attenuated dose change for the study was found to be -8.8% for 6 MV and -6.6% for 18 MV. This study presents the first comparison of therapeutic radiation delivery versus computerized treatment simulation involving cochlear implants.