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Dynamic Time Warping for Automated Cell Cycle Labelling. A. El-Labban, A. Zisserman University of Oxford. Y. Toyoda, A. Bird, A. Hyman Max Planck Institute of Molecular Cell Biology and Genetics. Objectives. Segment and track mitotic cells Label mitotic phases Fully automated system.
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Dynamic Time Warping for Automated Cell Cycle Labelling A. El-Labban, A. Zisserman University of Oxford Y. Toyoda, A. Bird, A. Hyman Max Planck Institute of Molecular Cell Biology and Genetics
Objectives • Segment and track mitotic cells • Label mitotic phases • Fully automated system Interphase Prometaphase Anaphase Telophase Prophase Metaphase
Data • 3D time lapse image stacks • Use max intensity z-projections • 1-5 minute temporal resolution • 0.2 micron xy-resolution
Approach • Existing approaches (e.g. Harder et al. 2009, Held et al. 2010 [CellCognition]): • Track cells • Label cell cycle phase frame-by-frame • Smooth result with HMM (CellCognition) • Our Approach: • Track cells • Label all frames by using temporal signals of features
Temporal signals of features Anaphase Interphase Prometaphase Telophase Prophase Metaphase
Overview • Part I • Track cells in videos • Part II • Label mitotic phases
Tracking • Tracking by detection • Detect first, then associate objects • Here we use detection by classification.
Segmentation: Our approach • Logistic regression classifier • Graph Cuts Logistic regression classifier Graph Cut Input image Probability map Binary map
Logistic Regression Classifier • Feature: • 10 bin intensity histogram in 5x5 window around pixel • Non-uniform bins • Get local neighbourhood information as opposed to single pixel • Histogram gives rotational invariance
Logistic Regression • Gives a probability map:
Graph Cuts Gradient dependent pairwise term Probability from Logistic Regression Classifier • Uses local neighbourhood information to make decisions • Pairwise term penalises different labels for adjacent pixels
Tracking • Associate objects based on distance between centroids in consecutive frames. • Easy given segmentation and slow movement of cells.
Tracking • Associate objects based on distance between centroids in consecutive frames. • Easy given segmentation and slow movement of cells.
Tracking • Associate objects based on distance between centroids in consecutive frames. • Easy given segmentation and slow movement of cells.
Simple features • Maximum Intensity: Interphase
Simple features • Maximum Intensity: Interphase Prophase
Simple features • Maximum Intensity: Interphase Prometaphase Prophase
Simple features • Maximum Intensity: Interphase Prometaphase Prophase Metaphase
Simple features • Maximum Intensity: Anaphase Interphase Prometaphase Prophase Metaphase
Simple features • Maximum Intensity: Anaphase Interphase Prometaphase Prophase Metaphase
Simple features • Maximum Intensity: Anaphase Interphase Prometaphase Telophase Prophase Metaphase
Reference signal • Average over training set (±1 standard deviation shaded):
Dynamic time warping • Stretch signal onto labelled reference:
Dynamic time warping • Stretch signal onto labelled reference:
Dynamic time warping Anaphase Interphase Prometaphase Interphase Telophase Prophase Metaphase
Dynamic time warping • Find a cost matrix of pairwise distances between points on the two signals • Find minimum cost path through matrix Test Signal Reference Signal
Features • Use 3 features and their gradients at two different scales: • Maximum intensity • Area • Compactness ( )
Hidden Markov Model • Hidden states, x • Mitotic phases • Observations, y • Features • Transition probabilities, a • From one phase to the next • Emission probabilities, b • Of features having a given value in a given phase Image: http://en.wikipedia.org/wiki/Hidden_Markov_model
Hidden Markov Model • DTW essentially a special case of HMM • Easy to extend approach • Can add other classes e.g. cell death • Split phases into sub-phases to account for variation
Experiments and Data • 54 movies • 119 mitotic tracks • 27 movies (61 tracks) training, 27 movies (58 tracks) testing
Results Interphase Prophase Prometaphase Metaphase Anaphase Telophase
Outputs • Synopsis video1 of mitotic cells • Aligned to start of anaphase 1Rav-Acha et al., 2006
Conclusions • Novel approach to cell cycle phase labelling • Utilises temporal context • Extendable with HMM