title: Ultrasound, a new tool for surface matching in computer-navigated surgery.
abstract: OBJECTIVE
  The object of this study was to investigate the feasibility of generating a bone surface from data provided by an ultrasound examination and to match this surface with the previous computed tomography (CT) scan.
  
  
  METHODS
  From a CT data set of a training model of the pelvis, a three-dimensional surface was extracted by global thresholding-based segmentation. The same model was placed in a water basin, and ultrasound images were taken with a guided ultrasound transducer. The three-dimensional surface was generated from the ultrasound data set, and the two surfaces were matched in a semiautomatic mode.
  
  
  RESULTS
  With special segmentation methods, a surface could be extracted automatically from the CT and the ultrasound data set. From these segmented ultrasound slices, a volume data set of the model was generated. After approximate initial matching, the local matching process was completed automatically.
  
  
  CONCLUSIONS
  One of the limitations in computer-assisted surgery is the complicated matching process. Using special algorithms, a surface was extracted from the data set of an ultrasound examination and matched in a semiautomatic mode with the surface of a CT data set, facilitating the matching process.
authors.affiliation: Department of Trauma and Reconstructive Surgery, University of Ulm, Ulm, Germany.
authors.forename: Ulrich C
authors.initials: UC
authors.lastname: Liener
authors.forename: Oleg
authors.initials: O
authors.lastname: Krivonos
authors.forename: Reinhard
authors.initials: R
authors.lastname: Männer
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hesser
authors.forename: Lothar
authors.initials: L
authors.lastname: Kinzl
authors.forename: Florian
authors.initials: F
authors.lastname: Gebhard
mesh_terms: D000465:Algorithms; D005240:Feasibility Studies; D006801:Humans; D025321:Surgery, Computer-Assisted; D014057:Tomography, X-Ray Computed / Q000379:methods; D014463:Ultrasonography / Q000191:economics / Q000379:methods*