title: Cone-beam CT versus multi-slice CT systems for postoperative imaging of cochlear implantation--a phantom study on image quality and radiation exposure using human temporal bones.
abstract: OBJECTIVE
  Image quality of low-dose multi-slice computed tomography (MSCT) after cochlear implantation is comparable to that of cone-beam computed tomography (CBCT).
  
  
  BACKGROUND
  CBCT has been described as a low-dose alternative with superior image quality to MSCT for postoperative cochlear implant (CI) imaging, but to our knowledge, no dose-matched comparisons of image quality have been published.
  
  
  METHODS
  Five human cochleae were implanted with CI electrodes and scanned on two CBCT and two MSCT systems. Four independent observers rated aspects of image quality on a five-point scale. CBCT scans were compared to clinical and dose-matched MSCT scans. Declining-dose MSCT protocols were compared to the clinical protocol. CT phantoms were used to determine effective dose and resolution for each acquisition protocol.
  
  
  RESULTS
  Effective dose of the CBCT protocols was 6 to 16% of the clinical MSCT dose. Visibility of cochlear inner and outer walls and overall image quality were positively correlated with radiation dose on MSCT and image quality was better with clinical MSCT than with CBCT protocols. In other comparisons, differences between systems were found, but a distinction between CBCT and MSCT could not be made.
  
  
  CONCLUSIONS
  CBCT and dose-matched MSCT are both suitable for postoperative CI imaging. Selecting a CT system and radiation dose depends on which cochlear structures need to be visualized.
authors.affiliation: *Department of Otorhinolaryngology and Head and Neck Surgery, Radboud university medical center and Hearing and Implants, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands; †Department of Radiology, Leiden University Medical Centre, Leiden, The Netherlands; ‡Department of Oral and Maxillofacial Surgery, 3D Facial Imaging Research Group, Radboud university medical center, Nijmegen, The Netherlands; and §Department of Radiology, Radboud university medical center, Nijmegen, The Netherlands.
authors.forename: Henricus J
authors.initials: HJ
authors.lastname: Theunisse
authors.forename: Raoul M S
authors.initials: RM
authors.lastname: Joemai
authors.forename: Thomas J J
authors.initials: TJ
authors.lastname: Maal
authors.forename: Jacob
authors.initials: J
authors.lastname: Geleijns
authors.forename: Emmanuel A M
authors.initials: EA
authors.lastname: Mylanus
authors.forename: Berit M
authors.initials: BM
authors.lastname: Verbist
mesh_terms: D002102:Cadaver; D003051:Cochlea / Q000000981:diagnostic imaging*; D019929:Cochlear Implantation; D003054:Cochlear Implants; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D019047:Phantoms, Imaging; D011184:Postoperative Period; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D013701:Temporal Bone / Q000000981:diagnostic imaging*; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000379:methods