title: Visualization of anterior skull base defects with intraoperative cone-beam CT.
abstract: BACKGROUND
  The role of cone-beam CT (CBCT) in demonstrating anterior skull base defects (ASBDs), differing in size and location, was investigated. The study was designed to describe the potential advantage of CBCT in the setting of an intraoperative cerebrospinal fluid (CSF) leak.
  
  
  METHODS
  In all, 120 ASBD were evaluated in 5 cadaver heads. Orthogonal and oblique slices were reconstructed. Observer studies assessed the visibility of ASBD in each location as a function of defect size.
  
  
  RESULTS
  For 1-, 2-, and 4-mm defects, the percentage that were undetectable ranged from 20% to 33%, 0% to 14%, and 0% to 5%, respectively. Confident breach detection increased with defect size and was most challenging in the lateral lamella and cribriform. CBCT permitted confident detection of ASBD as small as about 2 mm in the fovea ethmoidalis and planum. Oblique views were found to be superior to orthogonal planes.
  
  
  CONCLUSIONS
  The ability to identify ASBD depended on the size and location of defect. Oblique viewing planes were optimal for ASBD visualization.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery, Department of Surgical Oncology, Princess Margaret Hospital, Toronto, Ontario, Canada. gidybahar@gmail.com
authors.forename: Gideon
authors.initials: G
authors.lastname: Bachar
authors.forename: Emma
authors.initials: E
authors.lastname: Barker
authors.forename: Harley
authors.initials: H
authors.lastname: Chan
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Daly
authors.forename: Sajendra
authors.initials: S
authors.lastname: Nithiananthan
authors.forename: Al
authors.initials: A
authors.lastname: Vescan
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Irish
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Siewerdsen
mesh_terms: D002102:Cadaver; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D005260:Female; D006257:Head / Q000000981:diagnostic imaging / Q000601:surgery; D006801:Humans; D008297:Male; D016343:Monitoring, Intraoperative / Q000295:instrumentation* / Q000379:methods; D015588:Observer Variation; D011336:Probability; D012680:Sensitivity and Specificity; D019291:Skull Base / Q000000981:diagnostic imaging* / Q000601:surgery*; D018709:Statistics, Nonparametric