title: Quantitative Assessment of Facial Asymmetry Using Three-Dimensional Surface Imaging in Adults: Validating the Precision and Repeatability of a Global Approach.
abstract: Comparison of global versus landmark analyses of facial asymmetry using three-dimensional photogrammetry to establish a precise method for evaluating facial asymmetry.
  
  
  
  The landmark-based approach utilized anthropometric data points. Our global approach involved registration of mirror images, independent of a midplane, to calculate a root mean square (RMS) value. We analyzed precision and technical and operator error of both methods.
  
  
  
  Three hundred fifty adults participated in this study.
  
  
  
  We found that the global method has better precision and repeatability with a significantly lower error rate than the landmark-based method. In adults, the average RMS was 0.6253 mm with a standard deviation of 0.16.
  
  
  
  Our facial asymmetry measurement is more accurate than landmark-based measurements. This method is quick, reliable, and results in generation of a RMS score and a corresponding color-coded facial map that highlights regions of higher and lower asymmetry. This method may be used as a screening tool for asymmetry in both the clinical and research settings.
authors.forename: Davida
authors.initials: D
authors.lastname: Kornreich
authors.forename: Adele A
authors.initials: AA
authors.lastname: Mitchell
authors.forename: Bryn D
authors.initials: BD
authors.lastname: Webb
authors.forename: Ingrid
authors.initials: I
authors.lastname: Cristian
authors.forename: Ethylin Wang
authors.initials: EW
authors.lastname: Jabs
mesh_terms: D000328:Adult; D059925:Anatomic Landmarks; D005146:Facial Asymmetry / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010780:Photogrammetry / Q000379:methods*; D015203:Reproducibility of Results
keywords: 3dMD; facial asymmetry; facial landmarks; hemifacial microsomia; oculoauriculovertebral spectrum; root mean square; three-dimensional photogrammetry