title: A new computed tomography method to identify meningitis-related cochlear ossification and fibrosis before cochlear implantation.
abstract: OBJECTIVE
  To develop a new method to determine the presence of intracochlear ossification and/or fibrosis in cochlear implantation candidates with bilateral profound deafness following meningitis.
  
  
  METHODS
  Diagnostic test assessment.
  
  
  METHODS
  A university hospital.
  
  
  METHODS
  This study involved 15 ears from 13 patients with profound deafness following meningitis who underwent cochlear implantation. These ears showed normal structures, soft tissue, partial bony occlusion, and complete bony occlusion in 4, 3, 2, and 6 ears, respectively. We measured radiodensity in Hounsfield units (HU) using 0.5-mm-thick axial high-resolution computed tomography image slices at 3 different levels in the basal turn, the fenestration, and inferior and ascending segment sites, located along the electrode-insertion path. Pixel-level analysis on the DICOM viewer yielded actual computed tomography values of intracochlear soft tissues by eliminating the partial volume effect. The values were compared with the intraoperative findings.
  
  
  RESULTS
  Values for ossification (n = 12) ranged from +547 HU to +1137 HU; for fibrosis (n = 11), from +154 HU to +574 HU; and for fluid (n = 22), from -49 HU to +255 HU. From these values, we developed 2 presets of window width (WW) and window level (WL): (1) WW: 1800, WL: 1100 (200 HU to 2000 HU) and (2) WW: 1500, WL: 1250 (500 HU to 2000 HU). The results using these 2 presets corresponded well to the intraoperative findings.
  
  
  CONCLUSIONS
  Our new method is easy and feasible for preoperative determination of the presence of cochlear ossification and/or fibrosis that develops following meningitis.
authors.affiliation: Departments of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
authors.forename: Kazunori
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Akinori
authors.initials: A
authors.lastname: Kashio
authors.forename: Harushi
authors.initials: H
authors.lastname: Mori
authors.forename: Atushi
authors.initials: A
authors.lastname: Ochi
authors.forename: Shotaro
authors.initials: S
authors.lastname: Karino
authors.forename: Takashi
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Akinobu
authors.initials: A
authors.lastname: Kakigi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Yamasoba
mesh_terms: D000328:Adult; D002648:Child; D002675:Child, Preschool; D015834:Cochlear Diseases / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology / Q000601:surgery; D019929:Cochlear Implantation / Q000009:adverse effects / Q000379:methods*; D003054:Cochlear Implants; D015331:Cohort Studies; D003638:Deafness / Q000000981:diagnostic imaging* / Q000209:etiology / Q000601:surgery; D005260:Female; D005355:Fibrosis / Q000000981:diagnostic imaging / Q000209:etiology / Q000473:pathology; D005500:Follow-Up Studies; D006785:Hospitals, University; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008581:Meningitis / Q000150:complications* / Q000175:diagnosis / Q000628:therapy; D009999:Ossification, Heterotopic / Q000000981:diagnostic imaging* / Q000209:etiology / Q000473:pathology / Q000601:surgery; D011300:Preoperative Care / Q000379:methods; D012189:Retrospective Studies; D018570:Risk Assessment; D014057:Tomography, X-Ray Computed / Q000379:methods; D016896:Treatment Outcome
keywords: HRCT; Hounsfield unit; cochlea ossification; cochlear implant; meningitis