Article

Fast interactive integration of cross-sectional image datasets and surface data for morphometric analysis.

Department of Biochemistry and Molecular Biology, University of Calgary, Canada.
Studies in health technology and informatics 02/2009; 142:183-8.
Source: PubMed

ABSTRACT To investigate external facial morphology and cell proliferation patterns and their relationship with cleft lip malformation in mice, we need to compare samples of mice tissue photographs and surface reconstructions from micro-CT scans obtained from mouse embryos. Tissue samples obtained through digital photography are typically misaligned with respect to each other, which prevents further analysis. We have developed a system for fast interactive alignment of these image stacks for volume reconstruction and data visualization and analysis in 3D. The system is designed to work in multiprocessor environments and can utilize an arbitrary number of processors, cutting down significantly the turnaround time and allowing users to quickly process sets of hundreds of high resolution images using a combination of automated and interactive tools. Additional modules are used to reconstruct the shape of the original subject. Our system is interactive, fully scalable and can be applied to any photographic sliced dataset, regardless of subject and reduces significantly the processing time for stack alignment.

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    ABSTRACT: Growing demand for three dimensional (3D) digital images of embryos for purposes of phenotypic assessment drives implementation of new histological and imaging techniques. Among these micro-computed tomography (microCT) has recently been utilized as an effective and practical method for generating images at resolutions permitting 3D quantitative analysis of gross morphological attributes of developing tissues and organs in embryonic mice. However, histological processing in preparation for microCT scanning induces changes in organ size and shape. Establishing normative expectations for experimentally induced changes in size and shape will be an important feature of 3D microCT-based phenotypic assessments, especially if quantifying differences in the values of those parameters between comparison sets of developing embryos is a primary aim. Toward that end, we assessed the nature and degree of morphological artifacts attending microCT scanning following use of common fixatives, using a two dimensional (2D) landmark geometric morphometric approach to track the accumulation of distortions affecting the embryonic head from the native, uterine state through to fixation and subsequent scanning. Bouin's fixation reduced average centroid sizes of embryonic mouse crania by approximately 30% and substantially altered the morphometric shape, as measured by the shift in Procrustes distance, from the unfixed state, after the data were normalized for naturally occurring shape variation. Subsequent microCT scanning produced negligible changes in size but did appear to reduce or even reverse fixation-induced random shape changes. Mixtures of paraformaldehyde + glutaraldehyde reduced average centroid sizes by 2-3%. Changes in craniofacial shape progressively increased post-fixation. The degree to which artifacts are introduced in the generation of random craniofacial shape variation relates to the degree of specimen dehydration during the initial fixation. Fixation methods that better maintain original craniofacial dimensions at reduced levels of dehydration and tissue shrinkage lead to the progressive accumulation of random shape variation during handling and data acquisition. In general, to the degree that embryonic organ size and shape factor into microCT-based phenotypic assessments, procedurally induced artifacts associated with fixation and scanning will influence results. Experimental designs will need to address these significant effects, either by employing alternative methods that minimize artifacts in the region of focus or in the interpretation of statistical patterns.
    BMC Developmental Biology 02/2010; 10:18. · 2.73 Impact Factor

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May 23, 2014