title: Intra-operative adjustment of standard planes in C-arm CT image data.
abstract: OBJECTIVE
  With the help of an intra-operative mobile C-arm CT, medical interventions can be verified and corrected, avoiding the need for a post-operative CT and a second intervention. An exact adjustment of standard plane positions is necessary for the best possible assessment of the anatomical regions of interest but the mobility of the C-arm causes the need for a time-consuming manual adjustment. In this article, we present an automatic plane adjustment at the example of calcaneal fractures.
  
  
  METHODS
  We developed two feature detection methods (2D and pseudo-3D) based on SURF key points and also transferred the SURF approach to 3D. Combined with an atlas-based registration, our algorithm adjusts the standard planes of the calcaneal C-arm images automatically. The robustness of the algorithms is evaluated using a clinical data set. Additionally, we tested the algorithm's performance for two registration approaches, two resolutions of C-arm images and two methods for metal artifact reduction.
  
  
  RESULTS
  For the feature extraction, the novel 3D-SURF approach performs best. As expected, a higher resolution ([Formula: see text] voxel) leads also to more robust feature points and is therefore slightly better than the [Formula: see text] voxel images (standard setting of device). Our comparison of two different artifact reduction methods and the complete removal of metal in the images shows that our approach is highly robust against artifacts and the number and position of metal implants.
  
  
  CONCLUSIONS
  By introducing our fast algorithmic processing pipeline, we developed the first steps for a fully automatic assistance system for the assessment of C-arm CT images.
authors: Division of Medical and Biological Informatics (E130), German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany. m.brehler@dkfz-heidelberg.de.
authors: Michael
authors: M
authors: Brehler
authors: Division of Medical and Biological Informatics (E130), German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
authors: Joseph
authors: J
authors: Görres
authors: BG Trauma Center, Ludwig-Guttmann-Straße 13, 67071, Ludwigshafen am Rhein, Germany. jochen.franke@bgu-ludwigshafen.de.
authors: Jochen
authors: J
authors: Franke
authors: Siemens AG, Healthcare Sector, Henkestr. 127, 91052, Erlangen, Germany. karl.barth@siemens.com.
authors: Karl
authors: K
authors: Barth
authors: BG Trauma Center, Ludwig-Guttmann-Straße 13, 67071, Ludwigshafen am Rhein, Germany.
authors: Sven Y
authors: SY
authors: Vetter
authors: BG Trauma Center, Ludwig-Guttmann-Straße 13, 67071, Ludwigshafen am Rhein, Germany.
authors: Paul A
authors: PA
authors: Grützner
authors: Division of Medical and Biological Informatics (E130), German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
authors: Hans-Peter
authors: HP
authors: Meinzer
authors: Mannheim University of Applied Sciences, Paul-Wittsack-Str. 10, 68163, Mannheim, Germany. i.wolf@hs-mannheim.de.
authors: Ivo
authors: I
authors: Wolf
authors: Division of Medical and Biological Informatics (E130), German Cancer Research Center, Im Neuenheimer Feld 280, 69120, Heidelberg, Germany.
authors: Diana
authors: D
authors: Nabers
mesh_terms: D000465:Algorithms; D064386:Ankle Fractures / Q000000981:diagnostic imaging* / Q000601:surgery; D002111:Calcaneus / Q000000981:diagnostic imaging / Q000293:injuries* / Q000601:surgery; D006801:Humans; D007091:Image Processing, Computer-Assisted; D057072:Intra-Articular Fractures / Q000000981:diagnostic imaging* / Q000601:surgery; D016343:Monitoring, Intraoperative; D011183:Postoperative Complications / Q000517:prevention & control; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: Calcaneus; Feature detection; Intra-operative imaging; Pseudo-3D; SURF; Standard planes