title: Geometric alignment of 2D gel electrophoresis images.
abstract: OBJECTIVE
  2D gel electrophoresis (2-DE) is the method of choice for analyzing protein expression in the field of proteomics, for example, comparing a reference with a test population. However, due to complex physical and chemical processes the locations of proteins generally vary in different 2-DE images. To cope with these variations, accurate geometric alignment of 2-DE images is important.
  
  
  METHODS
  We introduce a new elastic registration approach for 2-DE images, which is based on an analytic solution of the Navier equation using Gaussian elastic body splines (GEBS). With this approach cross-effects in elastic deformations can be handled, which is important for the registration of 2-DE images. In addition, landmark correspondences can be included to aid the registration in regions which are difficult to register using intensity information alone.
  
  
  RESULTS
  We have successfully applied our approach to register 2-DE gel images of different levels of complexity. In each case, gel images from a reference group are compared with a test group. To analyze the performance of our approach, we have carried out a quantitative evaluation of the registration results. Moreover, we have performed an experimental comparison with a previous elastic registration scheme.
  
  
  CONCLUSIONS
  From the results we found that our approach is well-suited for the registration of 2-DE gel images of different levels of complexity and it turned out that the approach is superior to a previous hybrid scheme. Moreover, our approach is well-suited in a fully automatic setting and the performance can further be improved when landmark correspondences are available.
authors.affiliation: University of Heidelberg, BIOQUANT, IPMB, and DKFZ Heidelberg, Department of Bioinformatics and Functional Genomics, Biomedical Computer Vision Group, Heidelberg, Germany. s.woerz@dkfz.de
authors.forename: S
authors.initials: S
authors.lastname: Wörz
authors.forename: M-L
authors.initials: ML
authors.lastname: Winz
authors.forename: K
authors.initials: K
authors.lastname: Rohr
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D007090:Image Interpretation, Computer-Assisted; D012815:Signal Processing, Computer-Assisted