title: Craniofacial landmarks in young children:  how reliable are measurements based on 3-dimensional imaging?
abstract: BACKGROUND
  Different approaches for 3-dimensional (3D) data acquisition of the facial surface are common nowadays. Meticulous evaluation has proven their level of precision and accuracy. However, the question remains as to which level of craniofacial landmarks, especially in young children, are reliable if identified in 3D images. Potential sources of error, aside from the systems technology itself, need to be identified and addressed. Reliable and unreliable landmarks have to be identified.
  
  
  METHODS
  The 3dMDface System was used in a clinical setting to evaluate the intraobserver repeatability of 27 craniofacial landmarks in 7 young children between 6 and 18 months of age with a total of 1134 measurements.
  
  
  RESULTS
  The handling of the system was mostly unproblematic. The mean 3D repeatability error was 0.82 mm, with a range of 0.26 mm to 2.40 mm, depending on the landmark. Single landmarks that have been shown to be relatively imprecise in 3D analysis could still provide highly accurate data if only 1 of the 3 spatial planes was relevant. There were no statistical differences from 1 patient to another.
  
  
  CONCLUSIONS
  Reliability in craniofacial measurements can be achieved by such 3D soft-tissue imaging techniques as the 3dMDface System, but one must always be aware that the degree of precision is strictly dependent on the landmark and axis in question.For further clinical investigations, the degree of reliability for each landmark evaluated must be addressed and taken into account.
authors.affiliation: Clinic for Cranio-Maxillofacial Surgery, University Hospital of Zurich, Zurich, Switzerland.
authors.forename: Philipp
authors.initials: P
authors.lastname: Metzler
authors.forename: Lea S
authors.initials: LS
authors.lastname: Bruegger
authors.forename: Astrid L
authors.initials: AL
authors.lastname: Kruse Gujer
authors.forename: Felix
authors.initials: F
authors.lastname: Matthews
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Zemann
authors.forename: Klaus W
authors.initials: KW
authors.lastname: Graetz
authors.forename: Heinz-Theo
authors.initials: HT
authors.lastname: Luebbers
mesh_terms: D002971:Cleft Lip / Q000473:pathology*; D002972:Cleft Palate / Q000473:pathology*; D005145:Face / Q000002:abnormalities*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D007223:Infant; D008297:Male; D010780:Photogrammetry / Q000379:methods*; D015203:Reproducibility of Results