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GMDS 2012: 57. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie e. V. (GMDS)

Deutsche Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie

16. - 20.09.2012, Braunschweig

Virtual bone reconstruction for forensic documentation

Meeting Abstract

  • Markus Alexander Auf der Mauer Asmuss - Universitätsklinikum Hamburg-Eppendorf, Deutschland
  • Eilin Jopp - Universitätsklinikum Hamburg-Eppendorf, Deutschland
  • Dennis Säring - Universitätsklinikum Hamburg-Eppendorf, Deutschland

GMDS 2012. 57. Jahrestagung der Deutschen Gesellschaft für Medizinische Informatik, Biometrie und Epidemiologie e.V. (GMDS). Braunschweig, 16.-20.09.2012. Düsseldorf: German Medical Science GMS Publishing House; 2012. Doc12gmds120

DOI: 10.3205/12gmds120, URN: urn:nbn:de:0183-12gmds1203

Veröffentlicht: 13. September 2012

© 2012 Auf der Mauer Asmuss et al.
Dieser Artikel ist ein Open Access-Artikel und steht unter den Creative Commons Lizenzbedingungen (http://creativecommons.org/licenses/by-nc-nd/3.0/deed.de). Er darf vervielfältigt, verbreitet und öffentlich zugänglich gemacht werden, vorausgesetzt dass Autor und Quelle genannt werden.


Gliederung

Text

Background: Medical imaging techniques and 3D modeling of image data have a growing importance in forensic investigations. They are used for the documentation of cases, the confirmation of autopsy findings and even to provide additional information [1], [2], [3].

The standard forensic post-mortem procedure for bone fractures is done in four steps: macerate, boil and join bone fragments and finally taking photographs. Due to actual imaging techniques and image processing the fracture reconstruction step can be recreated virtually. The problem here is handling a surface model with a 2D input device in a 3D virtual scene. Therefore in [4] haptic devices were used for the reconstruction. This approach requires considerable user-interaction time and training. The aim of our work is to evaluate methods that enable a semi-automatic reconstruction with reduced interaction time. For this purpose, a landmark-based registration [5] was implemented into our software tool.

Materials and Methods: CT data was acquired from an actual forensic case with multiple fractures. For the evaluation of the reconstruction process using the registration approach a gold-standard is needed. Therefore, two small fragments of a humeral bone were generated by cutting the bone in half once with a plane and once with a free form line. The fragments were placed in the 3D scene randomly and reassembled using a different number of landmarks (n=4,6,10,20) per surface. This was repeated five times for each scenario. For the quantitative evaluation distances between landmarks and distances between the reconstructed surface model and the gold-standard were computed. Finally, the method was applied on the real femur fracture and the result was rated qualitatively.

Results: For both scenarios the lowest average mean distance between the reconstructed surface model and the gold-standard was achieved using n=20 landmarks, values being 0,034 mm for the first scenario and 0,056 mm for the second one. Placing n=10 landmarks instead, reduces the interaction time 50% and aggravates our distances by about 23% and 16% respectively. Similar behavior was observed with the distances between the correspondent landmarks after the registration.

Lastly, the real femur fracture was reconstructed. The forensic expert evaluated the result as acceptable for forensic documentation. Pictures from different camera views or even videos can improve the quality of the documentation.

Conclusions: Overall, our semi-automatic method returned good qualitative and quantitative results and required less interaction time than manual and haptic approaches. A tendency of lower surface distances using more landmarks was observed. Thus, an idea for the future could be to perform the reconstruction of the surface models by extracting and registering the fracture lines of both fragments.


References

1.
Thali MJ, Braun M, Dirnhofer R. Optical 3D surface digitizing in forensic medicine: 3D documentation of skin and bone injuries. Forensic Sci Int. 2003;137:203-8.
2.
Buck U, Naether S, Braun M, Bolliger S, Friederich H, Jackowski C, Aghayev A, Christe A, Vock P, Dirnhofer R, Thali MJ. Application of 3D documentation and geometric reconstruction methods in traffic accident analysis: with high resolution surface scanning, radiological MSCT/MRI scanning and real data based animation. Forensic Sci Int. 2007;170(1):20-8.
3.
Thali MJ, Braun M, Wirth J, Vock P, Dirnhofer R. 3D surface and body documentation in forensic medicine: 3-D/CAD Photogrammetry merged with 3D radiological scanning. J Forensic Sci. 2003;48(6):1356-65.
4.
Buck U, Naether S, Braun M, Thali MJ. Haptics in forensics: the possibilities and advantages in using the haptic device for reconstruction approaches in forensic science. Forensic Sci Int. 2008;180(2-3):86-92.
5.
Berthold KP. Horn, Closed-form solution of absolute orientation using unit quaternions. Journal of the Optical Society. 1987;4(4):629-42.