2D- and 3D-based measurements of orbital floor fractures from CT scans.
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.
Ploder
Oliver
O
Department of Cranio-Maxillofacial and Oral Surgery, General Hospital and Medical School, Universisty of Viena, Austria. oliver.ploder@univie.ac.at
Klug
Clemens
C
Backfrieder
Werner
W
Voracek
Martin
M
Czerny
Christian
C
Tschabitscher
Manfred
M
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*