Compensation of Missing Wedge Effects with Sequential Statistical Reconstruction in Electron Tomography

Lassi Paavolainen, Erman Acar, Uygar Tuna, Sari Peltonen, Toshio Moriya, Pan Soonsawad, Varpu Marjomaki, R. Holland Cheng, Ulla Ruotsalainen

    Research output: Contribution to journalArticleScientificpeer-review

    16 Citations (Scopus)

    Abstract

    Electron tomography (ET) of biological samples is used to study the organization and the structure of the whole cell and subcellular complexes in great detail. However, projections cannot be acquired over full tilt angle range with biological samples in electron microscopy. ET image reconstruction can be considered an ill-posed problem because of this missing information. This results in artifacts, seen as the loss of three-dimensional (3D) resolution in the reconstructed images. The goal of this study was to achieve isotropic resolution with a statistical reconstruction method, sequential maximum a posteriori expectation maximization (sMAP-EM), using no prior morphological knowledge about the specimen. The missing wedge effects on sMAP-EM were examined with a synthetic cell phantom to assess the effects of noise. An experimental dataset of a multivesicular body was evaluated with a number of gold particles. An ellipsoid fitting based method was developed to realize the quantitative measures elongation and contrast in an automated, objective, and reliable way. The method statistically evaluates the sub-volumes containing gold particles randomly located in various parts of the whole volume, thus giving information about the robustness of the volume reconstruction. The quantitative results were also compared with reconstructions made with widely-used weighted backprojection and simultaneous iterative reconstruction technique methods. The results showed that the proposed sMAP-EM method significantly suppresses the effects of the missing information producing isotropic resolution. Furthermore, this method improves the contrast ratio, enhancing the applicability of further automatic and semi-automatic analysis. These improvements in ET reconstruction by sMAP-EM enable analysis of subcellular structures with higher three-dimensional resolution and contrast than conventional methods.

    Translated title of the contributionCompensation of Missing Wedge Effects with Sequential Statistical Reconstruction in Electron Tomography
    Original languageEnglish
    Article number108978
    Number of pages14
    JournalPLoS ONE
    Volume9
    Issue number10
    DOIs
    Publication statusPublished - 3 Oct 2014
    Publication typeA1 Journal article-refereed

    Keywords

    • IMAGE-RECONSTRUCTION
    • EMISSION-TOMOGRAPHY
    • BAYESIAN-APPROACH
    • AXIS TOMOGRAPHY
    • ALGORITHM
    • RESOLUTION
    • MAXIMUM

    Publication forum classification

    • Publication forum level 2

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