title: 2D- and 3D-based measurements of orbital floor fractures from CT scans.
abstract: OBJECTIVE
  Two methods for area and volume calculation of the orbit were evaluated following blow-out fractures of the orbital floor using computed tomography (CT) scans.
  
  
  METHODS
  Isolated blow-out fractures of the orbital floor in human cadavers were simulated by fracturing the orbital floor and placing a defined volume of silicone within each defect. The area of fracture and the volume of silicone simulating herniated periorbital tissue were evaluated in 16 orbits by the use of a three-dimensional (3D) CT-based software package (Analyze((R)); Mayo Clinic, Rochester, MN, USA) and software based on two-dimensional (2D) coronal CT scans. Both methods were compared with direct anatomical measurements and evaluated with Lin's concordance coefficient (rho(c)).
  
  
  RESULTS
  Between-method concordance of area and volume calculation were rho(c)=0.962, and 0.872 for the 3D-CT-based method, and 0.981 and 0.952 for the 2D-CT method, respectively. The time allocated for measurement was significantly longer for the 3D-CT than for the 2D-CT method (p<0.001).
  
  
  CONCLUSIONS
  Calculations of blow-out fractures of the orbital floor by 3D-CT and 2D-CT method are accurate for assessing the area of fracture and the volume of herniated tissue. Lesser processing time and simple usage favour the 2D-CT-based calculation method.
authors.affiliation: Department of Cranio-Maxillofacial and Oral Surgery, General Hospital and Medical School, Universisty of Viena, Austria. oliver.ploder@univie.ac.at
authors.forename: Oliver
authors.initials: O
authors.lastname: Ploder
authors.forename: Clemens
authors.initials: C
authors.lastname: Klug
authors.forename: Werner
authors.initials: W
authors.lastname: Backfrieder
authors.forename: Martin
authors.initials: M
authors.lastname: Voracek
authors.forename: Christian
authors.initials: C
authors.lastname: Czerny
authors.forename: Manfred
authors.initials: M
authors.lastname: Tschabitscher
mesh_terms: D002102:Cadaver; D002508:Cephalometry / Q000379:methods; D006547:Hernia / Q000000981:diagnostic imaging; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D009916:Orbital Diseases / Q000000981:diagnostic imaging; D009917:Orbital Fractures / Q000000981:diagnostic imaging*; D015203:Reproducibility of Results; D012984:Software; D013223:Statistics as Topic; D014057:Tomography, X-Ray Computed / Q000379:methods*