title: Evaluation of portable CT scanners for otologic image-guided surgery.
abstract: OBJECTIVE
  Portable CT scanners are beneficial for diagnosis in the intensive care unit, emergency room, and operating room. Portable fixed-base versus translating-base CT systems were evaluated for otologic image-guided surgical (IGS) applications based on geometric accuracy and utility for percutaneous cochlear implantation.
  
  
  METHODS
  Five cadaveric skulls were fitted with fiducial markers and scanned using both a translating-base, 8-slice CT scanner (CereTom(®)) and a fixed-base, flat-panel, volume CT (fpVCT) scanner (Xoran xCAT(®)). Images were analyzed for: (a) subjective quality (i.e., noise), (b) consistency of attenuation measurements (Hounsfield units) across similar tissue, and (c) geometric accuracy of fiducial marker positions. The utility of these scanners in clinical IGS cases was tested.
  
  
  RESULTS
  Five cadaveric specimens were scanned using each of the scanners. The translating-base, 8-slice CT scanner had spatially consistent Hounsfield units, and the image quality was subjectively good. However, because of movement variations during scanning, the geometric accuracy of fiducial marker positions was low. The fixed-base, fpVCT system had high spatial resolution, but the images were noisy and had spatially inconsistent attenuation measurements, while the geometric representation of the fiducial markers was highly accurate.
  
  
  CONCLUSIONS
  Two types of portable CT scanners were evaluated for otologic IGS. The translating-base, 8-slice CT scanner provided better image quality than a fixed-base, fpVCT scanner. However, the inherent error in three-dimensional spatial relationships by the translating-based system makes it suboptimal for otologic IGS use.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, 1215 21st Avenue South, 10450 Medical Center East, South Tower, Nashville, TN 37232, USA. ramya.balachandran@vanderbilt.edu
authors.forename: Ramya
authors.initials: R
authors.lastname: Balachandran
authors.forename: Daniel
authors.initials: D
authors.lastname: Schurzig
authors.forename: J Michael
authors.initials: JM
authors.lastname: Fitzpatrick
authors.forename: Robert F
authors.initials: RF
authors.lastname: Labadie
mesh_terms: D002102:Cadaver; D007758:Ear, Inner / Q000000981:diagnostic imaging* / Q000601:surgery; D004867:Equipment Design; D004869:Equipment Safety; D006801:Humans; D061330:Multidetector Computed Tomography / Q000379:methods*; D013506:Otologic Surgical Procedures / Q000379:methods*; D019095:Point-of-Care Systems; D015641:Radiography, Interventional; D015203:Reproducibility of Results; D012886:Skull / Q000000981:diagnostic imaging