title: Measurement of Cochlear Implant Electrode Position From Intraoperative Post-insertion Skull Radiographs: A Validation Study.
abstract: OBJECTIVE
  To validate a method of measuring angular depth of insertion (aDOI) as well as positional depth of each electrode contact in a cochlear implant by using intraoperative postinsertion skull radiographs.
  
  
  METHODS
  Retrospective review.
  
  
  METHODS
  Tertiary referral center.
  
  
  METHODS
  Intraoperative postinsertion radiographs obtained from 18 cochlear implant recipients were chosen for analysis. One high-resolution computer tomography scan of the head with the electrode in place was also analyzed. One cadaveric temporal bone with an inserted electrode provided additional data for analysis.
  
  
  METHODS
  aDOI and position of each electrode contact were measured from the radiographs using readily available software. High-resolution computer tomography imaging of the cochlea and electrode were reconstructed in three dimensions and used to simulate head rotation during intraoperative radiographs. The cadaveric temporal bone was imaged by x-ray at various acquisition angles.
  
  
  METHODS
  We evaluated the error introduced in measuring aDOI by assessing intra- and inter-rater variability. We also evaluated the error introduced by x-ray acquisition at nonstandardized angles by analyzing the three-dimensional construct and the cadaveric temporal bone.
  
  
  RESULTS
  The concordance correlation coefficients for intrarater (0.991) and inter-rater (0.996) variability in aDOI measurement were excellent. The error introduced by nonstandardized x-ray acquisition angles was only -12.5 degrees to +15.8 degrees even at the limits of clinically relevant head rotation.
  
  
  CONCLUSIONS
  The intraoperative postinsertion radiograph is sufficient for estimating positional depth of electrode contacts and the aDOI. This measure is robust in the face of nonstandardized x-ray acquisition angles, and shows good intra- and inter-rater variability.
authors.affiliation: *Department of Otolaryngology and Communicative Disorders, North Shore Long Island Jewish Medical Center †Department of Otolaryngology ‡Department of Radiology, New York University Langone Medical Center, New York, New York, U.S.A.
authors.forename: Maja
authors.initials: M
authors.lastname: Svrakic
authors.forename: David R
authors.initials: DR
authors.lastname: Friedmann
authors.forename: Phillip M
authors.initials: PM
authors.lastname: Berman
authors.forename: Adam J
authors.initials: AJ
authors.lastname: Davis
authors.forename: J Thomas
authors.initials: JT
authors.lastname: Roland
authors.forename: Mario A
authors.initials: MA
authors.lastname: Svirsky
mesh_terms: D000328:Adult; D002648:Child; D003051:Cochlea / Q000000981:diagnostic imaging* / Q000601:surgery; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D004567:Electrodes, Implanted; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007430:Intraoperative Care / Q000379:methods; D008297:Male; D012189:Retrospective Studies; D012984:Software; D025321:Surgery, Computer-Assisted; D013701:Temporal Bone / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*