gms | German Medical Science

Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

Micro-Ct As Innovatory Technique For Evaluation Of The Intracochlear Positioning Of Cochlear Implant Electrodes

Meeting Abstract

  • A. Zarowski - University ENT Department, St. Augustinus Medical Centre, University of Antwerp
  • A. Postnov - Vision Lab, Microtomography, University of Antwerp
  • F. Vanpoucke - Laboratory of Medical Electronics, University of Antwerp
  • N. DeClerck - Vision Lab, Microtomography, University of Antwerp
  • F.E. Offeciers - University ENT Department, St. Augustinus Medical Centre, University of Antwerp
  • S. Peeters - Laboratory of Medical Electronics, University of Antwerp

Medical University of Hannover, Department of Otolaryngology. Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants. Hannover, 01.-04.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05omci065

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Veröffentlicht: 31. Mai 2005

© 2005 Zarowski et al.
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Gliederung

Text

Introduction

Micro-CT is an innovatory technique of computerized tomography that is highly optimized for accuracy. It allows for scanning of samples with dimensions in the cm range including small laboratory animals such as rats. Excellent resolution (down to 5 μm) makes micro-CT potentially competitive to standard histological techniques due mainly to minimal necessary sample manipulation and preparation. First applications of micro-CT for evaluation of the intracochlear tissues without and with implanted cochlear implant (CI) electrodes in human temporal bones are described here. Objective: To define and apply a micro-CT protocol allowing for artifact- and metallic scattering-free visualization of the intracochlear tissues without and with implanted CI electrodes and for evaluation of the insertion safety of the newly developed CI electrodes.

Materials and Methods

In this study the in-vivo Skyscan-1076 micro-CT machine has been used. It has the maximal field of view of 68 mm, a rotating 5 μm X-ray source and a 2D CCD camera with 9 μm pixel size. Good visualization of the intracochlear soft tissues has been achieved using a Ti-filter and extra-long scanning times. Acquired shadow projections have been reconstructed as virtual slices using the Feldkamp algorithm and the 3-D models have been built from the obtained cross-sections. The ANT Skyscan software has been used for volume visualizations. In order to remove the scattering caused by the metallic electrode contacts the samples have been scanned twice (with Ti- and A1-filters) and afterwards the digital subtraction/ superposition techniques have been applied. Electrodes used for insertion experiments were the Advanced Bionics (AB) Hi-Focus II electrodes without positioner as well as the new AB Helix electrode.

Results

Micro-CT has been used for evaluation of the intracochlear anatomy before and after insertion of the CI electrodes. It allowed for a reliable and artifact-free acquisition of the nearly-histological-quality images of the intracochlear tissues. Also the cochlea's with inserted electrodes could be viewed section after section along the whole length of the cochlear turns, clearly showing the electrodes' positions relative to the modiolus, the basilar membrane, etc. The scattering caused by the metallic parts of the inserted electrode could effectively be removed.

Conclusions

Micro-CT is a very accurate technique allowing for a clinically relevant artifact-free evaluation of the intracochlear tissues after insertion of design CI electrodes.