Bioinformatics Advance Access published online on August 14, 2008
Bioinformatics, doi:10.1093/bioinformatics/btn426
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Graphical Methods for Quantifying Macromolecules through Bright Field Imaging
1Lawrence Berkeley National Laboratory, Berkeley, CA 94720.
2Institute of Automation, Chinese Academy of Sciences, Beijing.
3Department of Pathology, University of California, San Francisco
4Department of Electrical Engineering, University of California, Riverside
To whom correspondence should be addressed. Hang Chang, E-mail: hchang{at}lbl.gov
| Abstract |
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Bright field imaging of biological samples stained with antibodies and/or special stains provides a rapid protocol for visualizing various macromolecules. However, this method of sample staining and imaging is rarely employed for direct quantitative analysis due to variations in sample fixations, ambiguities introduced by color composition, and the limited dynamic range of imaging instruments. We demonstrate that, through the decomposition of color signals, staining is scored on a cell-by-cell basis. We applied our method to fibroblasts grown from histologically normal breast tissue biopsies obtained from two distinct populations. Firstly, nuclear regions are initially segmented through conversion of color images into gray scale, and detection of dark elliptic features. Subsequently, the strength of staining is quantified by a color decomposition model that is optimized by a graph cut algorithm. In rare cases where nuclear signal is significantly altered as a result of sample preparation, nuclear segmentation can be validated and corrected. Finally, stained patterns are associated with each nuclear region following region-based tessellation. Compared to classical non-negative matrix factorization, our new proposed method (i) improves color decomposition, (ii) has a better noise immunity, (iii) is more invariant to initial conditions, and (iv) has a superior computing performance.
Associate Editor: Dr. Jonathan Wren
Received on March 12, 2008; revised on August 9, 2008; accepted on August 10, 2008