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Published byJoel Wells Modified over 9 years ago
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IMAGE INFORMATICS SOLUTIONS Extracting Information From Images Array-Pro 4.5 Training, May 2003
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Array-Pro Analyzer
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Experiment Model Template concept Experiment definition Default parameters Demo macro: Create Grid Finding Template
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Experiment Driven
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Image Acquisition From scanner From files
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Image Examination Overall image quality On-screen optimization Understanding the intended grid layout Spot shape
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General Image Analysis Tools Contrast enhancement AOI Navigation and zoom Colorize/color channel Filters Operations Convert/duplicate Surface plot
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Template Method Development Conceptual framework Rotation Grid location line distance AOI (bounding rectangle) Spot location algorithms Sub-grid definition Cell boundary definition Multiple grid zones Hands on practice
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Spot location definition –On the first image (creating a template) –On other images Background correction technique Normalization technique Greatest Image Analysis Error Sources
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Spot ID Wizard
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Auto Grid/Spot Detection Parameters
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Advanced Detection
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Grid Adjustment Manual Save/load/copy/paste Auto align Using Extended auto-align
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Spot Descriptors ASCII input GAL files URL lookup
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Replicates within an experiment Adjacent Free assignment By sub-grid By labels
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How Do You Know Whether Your Data Is Good? Replicates –Is it reproducible within acceptable error? –A tenet of science Standards –No gold standard –Even housekeeping genes change under most experimental conditions –Does it compare favorably to Northern blots?
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Replicate Handling in Array-Pro
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Replicates (Cont)
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Replicate Reporting With so many variables with microarrays, instead of trying to interpret a bad spot image (making assumptions that may not be valid), bad data can be discarded yet still have enough for analysis
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Measurements Conceptual framework Primary vs. informational measurements Meaning of Net intensity and background
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Measurements & Statistics Available at four levels –Spots –Replicates –Image groups –Collections of image groups
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Measurements & Descriptors
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Spot Measurements
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Image Group Measurements
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Quality Metrics User definable Some common ones –Standard deviation of the background pixels –Inertia diameter (indication of spot shape/uniformity) –Spot shift –Number of pixels within threshold
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Quality Metrics Spot quality metrics User-defined parameters Automatic cell flagging Array quality metrics
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Optimized Results Only cells failing quality metrics removed; ratio near expected; mean and median ratio close
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Scatter-plot Display Default method; good but wide variation at low signal; Cy5 signal strength causes distortion Optimized results with much less variance at low signal; excellent linearity
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View and Labels User feedback definition Color assignment
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Signal Optimization Background concept Background methods Net intensity definition as found in measurements data table
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Background Characterization
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Appropriate Noise Treatment Not as many cells ignored Using statistical parameters: –Mean, Median, Ranked percentile, Trimmed mean Background methods Pre-filtering Net intensity definition as found in measurements data table
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Using Local Corners About the same
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Normalization Theory Methods
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Normalization methods
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Greatest Sources of Image Acquisition Error Garbage In Garbage Out –Image analysis can only go so far Dynamic range imbalance of Cy5/Cy3 –Take advantage of 65,536 counts of a 16-bit image Saturation –Pixels truncate at the top end Bleaching –Due to high laser intensity Optics Mechanics
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Major Factors Influencing Fluorescent Intensity Readings Particulate reflection –Typically 2 to 100 X compared to highest fluorescent signal Temperature pH Oxygen Buffer strength Analyte concentration Time Hybridization efficiency –Kinetics, depletion, etc.
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CY3/Cy5 Intensity Curves
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Background/Normalization Correction
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Data Windows Scatterplot Data table Histogram Cell window Data Graph Information table
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Cell Groups Standard Custom Derived Automatic cell flagging
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Cell Groups One can put any group of cells into groups for interpretation
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Histogram Any measurement or cell group can be displayed; interactive with all other data display windows
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Cell Window
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Scatter Plot
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Data Graph
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Data Table For information to sort cells and for reporting
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Statistical Feedback
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Info Table (Cells)
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Info Table (Images)
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Cell Group Information
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Image Groups Hierarchy Labels
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Macro Programming Demo macros Macro recorder Sample macros
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Selling Feature/benefits Demonstration –Overview presentation Demo movies Demo macros –In-depth technical selling to qualified prospects
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HEADQUARTERS Media Cybernetics, Inc. 8484 Georgia Avenue, Suite 200 Silver Spring, MD 20910 USA Phone: + 1 301 495 3305 Fax: + 1 301 495 5964 Email: info@mediacy.com Web:www.mediacy.com
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