title: In vivo estimates of the position of advanced bionics electrode arrays in the human cochlea.
abstract: OBJECTIVE
  A new technique for determining the position of each electrode in the cochlea is described and applied to spiral computed tomography data from 15 patients implanted with Advanced Bionics HiFocus I, Ij, or Helix arrays.
  
  
  METHODS
  ANALYZE imaging software was used to register 3-dimensional image volumes from patients' preoperative and postoperative scans and from a single body donor whose unimplanted ears were scanned clinically, with micro computed tomography and with orthogonal-plane fluorescence optical sectioning (OPFOS) microscopy. By use of this registration, we compared the atlas of OPFOS images of soft tissue within the body donor's cochlea with the bone and fluid/ tissue boundary available in patient scan data to choose the midmodiolar axis position and judge the electrode position in the scala tympani or scala vestibuli, including the distance to the medial and lateral scalar walls. The angular rotation 0 degrees start point is a line joining the midmodiolar axis and the middle of the cochlear canal entry from the vestibule.
  
  
  RESULTS
  The group mean array insertion depth was 477 degrees (range, 286 degrees to 655 degrees). The word scores were negatively correlated (r = -0.59; p = .028) with the number of electrodes in the scala vestibuli.
  
  
  CONCLUSIONS
  Although the individual variability in all measures was large, repeated patterns of suboptimal electrode placement were observed across subjects, underscoring the applicability of this technique.
authors.affiliation: Dept of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, 660 N Euclid Ave, Campus Box 8115, St Louis, MO 63110, USA.
authors.forename: Margaret W
authors.initials: MW
authors.lastname: Skinner
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Holden
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Whiting
authors.forename: Arne H
authors.initials: AH
authors.lastname: Voie
authors.forename: Barry
authors.initials: B
authors.lastname: Brunsden
authors.forename: J Gail
authors.initials: JG
authors.lastname: Neely
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Saxon
authors.forename: Timothy E
authors.initials: TE
authors.lastname: Hullar
authors.forename: Charles C
authors.initials: CC
authors.lastname: Finley
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003051:Cochlea / Q000000981:diagnostic imaging* / Q000473:pathology*; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D005260:Female; D034381:Hearing Loss / Q000000981:diagnostic imaging / Q000473:pathology / Q000628:therapy*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome