Merged Volume Rendered Flat-panel Computed Tomography for Postoperative Cochlear Implant Assessment.

Abstract

Evaluation of anew postprocessing method for postoperative control of cochlear implants (CI) based on asingle flat detector computed tomography (FD-CT) run and volume rendering of 3D models of the inner ear. The FD-CT datasets of CIs were selected and postprocessed to generate both standard multiplanar reconstructions (MPR) and merged volume-rendered 3D datasets (MRD) of the CIs. The MRDs consisted of two different reconstructions (bone/implant) that are automatically layered to avoid manual coregistration inaccuracy. Corresponding datasets were evaluated in consensus reading in terms of qualitative (integrity, position, configuration) and quantitative (insertion depth angle) CI parameters. In total 20FD-CTs with 20CIs were successfully postprocessed. Qualitative evaluation of MPR and MRD demonstrated complete congruency (integrity: narray integrity = 20; position: nscala tympani = 13, nscalar translocation = 7; configuration: nharmonic spiralization = 16, ntip fold over = 3, nlooped implant = 1). Adverse intracochlear implant spiralization was identified in all 10cases with MRD and MPR. Measurement of the insertion depth angle in MRD was equivalent to that in MPR (r = 0.99; P = <0.0001). The use of MRD is ahelpful method for precise postoperative CI assessment and provides easy detection of incorrect intracochlear spiralization.