title: Intra-operative assessment of fractured articular surfaces in cone beam CT image data.
abstract: OBJECTIVE
  The assessment of intra-operatively acquired volumetric data is a difficult and often time-consuming task, which demands a new set of skills from the surgeons. In the case of orthopedic surgeries such as the treatment of calcaneal fractures, the correctness of the reduction of the bone fragments can be verified with the help of C-arm CT volumetric images. For an accurate intra-operative assessment of the displaced fragments, an automatic segmentation of the articular surfaces and color-coded visualization was developed.
  
  
  METHODS
  Our automatic approach consists of three major steps: first, using adjusted standard planes intersecting the articular region, the joint space is localized with an intensity profile-based method. In a second step, the localized joint space is segmented on the Laplacian of Gaussian filtered volumetric image by a modified binary flood fill algorithm. Finally, a 3D surface model of the segmented joint space is analyzed and visualized with focus on critical displacements of the surface.
  
  
  RESULTS
  A specifically designed human cadaver study consisting of ten lower legs of ten different donors was conducted to acquire 48 realistic C-arm CT images of misaligned bone fragments (steps of varying sizes) in the posterior talar articular surface of the calcaneus. The proposed algorithmic pipeline was verified by the acquired image data and showed very good results with no false positives and an overall correct displacement assessment of 93.8%.
  
  
  CONCLUSIONS
  The proposed algorithmic pipeline can be easily integrated into the clinical workflow and qualifies for intra-operative usage. It showed very good results on the reference data set of the cadaver study. With the help of such an assistance system, the time-consuming process of 2D view adjustment and visual assessment of the gray value images can be greatly simplified.
authors.affiliation: Division of Medical and Biological Informatics (E130), German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany. m.brehler@dkfz-heidelberg.de.
authors.forename: Michael
authors.initials: M
authors.lastname: Brehler
authors.affiliation: Division of Medical and Biological Informatics (E130), German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
authors.forename: Joseph
authors.initials: J
authors.lastname: Görres
authors.affiliation: BG Trauma Center, Ludwig-Guttmann-Strae 13, 67071, Ludwigshafen, Germany.
authors.forename: Sven Y
authors.initials: SY
authors.lastname: Vetter
authors.affiliation: BG Trauma Center, Ludwig-Guttmann-Strae 13, 67071, Ludwigshafen, Germany.
authors.forename: Jochen
authors.initials: J
authors.lastname: Franke
authors.affiliation: BG Trauma Center, Ludwig-Guttmann-Strae 13, 67071, Ludwigshafen, Germany.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Grützner
authors.affiliation: Division of Medical and Biological Informatics (E130), German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Meinzer
authors.affiliation: Mannheim University of Applied Sciences, Paul-Wittsack-Str. 10, 68163, Mannheim, Germany.
authors.forename: Ivo
authors.initials: I
authors.lastname: Wolf
mesh_terms: D000465:Algorithms; D002102:Cadaver; D002111:Calcaneus / Q000000981:diagnostic imaging*; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D050723:Fractures, Bone / Q000000981:diagnostic imaging*; D006801:Humans
keywords: Articular surface; C-arm CT; Displacement detection; Intra-operative assessment; Laplacian of Gaussian; Segmentation