title: Automatic measurement of vertebral rotation in idiopathic scoliosis.
abstract: METHODS
  Development of an automatic measurement algorithm and comparison with manual measurement methods.
  
  
  OBJECTIVE
  To develop a new computer-based method for automatic measurement of vertebral rotation in idiopathic scoliosis from computed tomography images and to compare the automatic method with two manual measurement techniques.
  
  
  BACKGROUND
  Techniques have been developed for vertebral rotation measurement in idiopathic scoliosis using plain radiographs, computed tomography, or magnetic resonance images. All of these techniques require manual selection of landmark points and are therefore subject to interobserver and intraobserver error.
  
  
  METHODS
  We developed a new method for automatic measurement of vertebral rotation in idiopathic scoliosis using a symmetry ratio algorithm. The automatic method provided values comparable with Aaro and Ho's manual measurement methods for a set of 19 transverse computed tomography slices through apical vertebrae, and with Aaro's method for a set of 204 reformatted computed tomography images through vertebral endplates.
  
  
  RESULTS
  Confidence intervals (95%) for intraobserver and interobserver variability using manual methods were in the range 5.5 degrees to 7.2 degrees . The mean (+/-SD) difference between automatic and manual rotation measurements for the 19 apical images was -0.5 degrees +/- 3.3 degrees for Aaro's method and 0.7 degrees +/- 3.4 degrees for Ho's method. The mean (+/-SD) difference between automatic and manual rotation measurements for the 204 endplate images was 0.25 degrees +/- 3.8 degrees .
  
  
  CONCLUSIONS
  The symmetry ratio algorithm allows automatic measurement of vertebral rotation in idiopathic scoliosis without intraobserver or interobserver error due to landmark point selection.
authors.affiliation: Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services Brisbane Ltd, Queensland, Australia. c.adam@qut.edu.au
authors.forename: Clayton J
authors.initials: CJ
authors.lastname: Adam
authors.forename: Geoffrey N
authors.initials: GN
authors.lastname: Askin
mesh_terms: D000465:Algorithms; D006801:Humans; D008159:Lumbar Vertebrae / Q000502:physiology*; D008954:Models, Biological; D012399:Rotation; D012600:Scoliosis / Q000503:physiopathology*; D013904:Thoracic Vertebrae / Q000502:physiology*; D014057:Tomography, X-Ray Computed / Q000379:methods