title: Three-dimensional computed tomography landmark measurement in craniofacial surgical planning: experimental validation in vitro.
abstract: OBJECTIVE
  This study evaluated the measurement accuracy of three-dimensional (3D) volumetric images from spiral computed tomography (CT) in vitro.
  
  
  METHODS
  The study sample consisted of nine cadaver heads that were submitted to an impact force by a special device to promote blunt traumatic craniofacial fractures. The heads were subsequently scanned by a spiral CT scanner (Toshiba Xpress S/X). The archived CT data were transferred to networked computer workstations (Sun Microsystems with Cemax VIP version 1.4 software) to generate 3D volumetric images. The visualization software was used to make interactive linear measurements on the 3D images. Measurements were made on the images twice by two observers, based on conventional craniofacial anatomic landmarks. The soft tissues were subsequently removed, and the same measurements were repeated on the cadaver heads with an electromagnetic digitizer (3 Space, Polhemus, Colchester, VT).
  
  
  RESULTS
  The results showed no statistically significant differences between the 3D-CT and the physical measurements, with P>.05 for all measurements. The mean difference between the image and real measurements was less than 2 mm in all instances.
  
  
  CONCLUSIONS
  It is concluded that measurement of the skull and facial bone landmarks by 3D reconstruction is quantitatively accurate for surgical planning and treatment evaluation of craniofacial fractures.
authors.affiliation: Department of Radiology, Faculty of Odontology, University of São Paulo, Brazil. mgpcaval@siso.fo.usp.br
authors.forename: M G
authors.initials: MG
authors.lastname: Cavalcanti
authors.forename: J W
authors.initials: JW
authors.lastname: Haller
authors.forename: M W
authors.initials: MW
authors.lastname: Vannier
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D002508:Cephalometry / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010347:Patient Care Planning; D012015:Reference Standards; D015203:Reproducibility of Results; D012887:Skull Fractures / Q000000981:diagnostic imaging* / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*