Hypothesis:
Flat-panel based volume
computed tomography could improve cochlear implant electrode evaluation in comparison with multislice
computed tomography.
Background:
Flat-panel based volume
computed tomography offers higher spatial resolution and less metal artifacts than multislice
computed tomography. Both characteristics could improve the evaluation of challenging but important questions in
cochlear implantation assessment, such as an exact imaging of cochlea, osseous spiral lamina, electrode array position, and single electrode contacts. These questions are not currently fully answered by multislice
computed tomography.
Methods:
Four isolated temporal bone specimens were scanned in a current multislice
computed tomography scanner and in two experimental flat-panel based volume
computed tomography scanners before and after cochlea implantation. To compare flat-panel based volume
computed tomography and multislice
computed tomography, four features were rated according to the following criteria: 1) visibility of the cochlea; 2) visibility of the osseous spiral lamina; 3) discernibility of individual electrode contacts; and 4) the ability to determine the electrode array position relative to scala tympani and scala vestibuli. Layer-by-layer microgrinding pictures were used as the ground truth for verification of imaging findings.
Results:
Flat-panel based volume
computed tomography was superior to multislice
computed tomography in all four features rated. The cochlea and facial nerve canal were much better delineated in flat-panel based volume
computed tomography. The osseous spiral lamina and single electrode contacts were only visible in flat-panel based volume
computed tomography. Assessment of implant position with regard to the cochlear spaces was considerably improved by flat-panel based volume
computed tomography.
Conclusion:
Cochlear implantation assessment could be improved by flat-panel based volume
computed tomography and, therefore, would be highly beneficial for cochlea implantation research and for clinical evaluation. However, these first results were shown by scanning isolated temporal bone specimens; scanning whole human skull bases might be more challenging.
