title: Registering 2D and 3D imaging data of bone during healing.
abstract: PURPOSE/AIMS OF THE STUDY: Bone's hierarchical structure can be visualized using a variety of methods. Many techniques, such as light and electron microscopy generate two-dimensional (2D) images, while micro-computed tomography (µCT) allows a direct representation of the three-dimensional (3D) structure. In addition, different methods provide complementary structural information, such as the arrangement of organic or inorganic compounds. The overall aim of the present study is to answer bone research questions by linking information of different 2D and 3D imaging techniques. A great challenge in combining different methods arises from the fact that they usually reflect different characteristics of the real structure.
  
  
  METHODS
  We investigated bone during healing by means of µCT and a couple of 2D methods. Backscattered electron images were used to qualitatively evaluate the tissue's calcium content and served as a position map for other experimental data. Nanoindentation and X-ray scattering experiments were performed to visualize mechanical and structural properties.
  
  
  RESULTS
  We present an approach for the registration of 2D data in a 3D µCT reference frame, where scanning electron microscopies serve as a methodic link. Backscattered electron images are perfectly suited for registration into µCT reference frames, since both show structures based on the same physical principles. We introduce specific registration tools that have been developed to perform the registration process in a semi-automatic way.
  
  
  CONCLUSIONS
  By applying this routine, we were able to exactly locate structural information (e.g. mineral particle properties) in the 3D bone volume. In bone healing studies this will help to better understand basic formation, remodeling and mineralization processes.
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces , Potsdam , Germany .
authors.forename: Rebecca M
authors.initials: RM
authors.lastname: Hoerth
authors.forename: Daniel
authors.initials: D
authors.lastname: Baum
authors.forename: David
authors.initials: D
authors.lastname: Knötel
authors.forename: Steffen
authors.initials: S
authors.lastname: Prohaska
authors.forename: Bettina M
authors.initials: BM
authors.lastname: Willie
authors.forename: Georg N
authors.initials: GN
authors.lastname: Duda
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Hege
authors.forename: Peter
authors.initials: P
authors.lastname: Fratzl
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wagermaier
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000473:pathology* / Q000648:ultrastructure; D017102:Fracture Healing; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008855:Microscopy, Electron, Scanning / Q000379:methods; D051381:Rats; D014057:Tomography, X-Ray Computed / Q000379:methods; D055114:X-Ray Microtomography
keywords: Backscattered electron imaging; micro-computed tomography; semi-automatic image registration; three-dimensional visualization