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AstraZeneca & University of Manchester Knees Project

Join us for the AstraZeneca & University of Manchester Knees Project Meeting to discuss the latest findings and future plans of the project. Topics include normal range, disease progression, correspondence points evaluation, statistical analysis, and more.

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AstraZeneca & University of Manchester Knees Project

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  1. AstraZeneca & University of ManchesterKnees Project Project Meeting ISBE, University of Manchester 16th October 2003 AZ/Manchester Knees Meeting

  2. Agenda • CP77 • Normal Range • CP78 • Detecting Disease Progression • Publication Plan AZ/Manchester Knees Meeting

  3. CP77 Data • Travellers: • 5 × 2 (legs) × 3 (sites) + (5 (Liv R2 scans) × 2 (legs)) = 40 • Statics: • 14 (4003 no bone scan) + 5 (Liv R2) = 19 • Segmentations • ZaiXiang Bone • Nick + Siân 105 cartilage segmentations • 4089 Correspondence Points • Mean Separation ≈2mm • Chemical Shift artefact correction AZ/Manchester Knees Meeting

  4. CP77 Correspondence Points’ Evaluation • Evaluation Criteria • Compactness, specificity, generalisation • Register Travellers’ Bone Surfaces • Apply transform to Correspondence Points • Measure distance to mean shape • Eval_correspondences.xls AZ/Manchester Knees Meeting

  5. Criteria AZ/Manchester Knees Meeting

  6. Correspondence Points Evaluation AZ/Manchester Knees Meeting

  7. CP77 Normal Range • Data • 5 (Travellers) × 2 (Legs) × (3+1) (Sites) = 40 bones • 64 Segmentations (n: 48 s: 16) • Distribution of Thickness Readings • Readings_distribution.fig • Cortical Bone and Cartilage Thickness • meancortthick.fig, meancartthick.fig • Standard Deviation of Thickness, T-test • stdthick.fig, ttestthick.fig AZ/Manchester Knees Meeting

  8. CP77 Normal Range AZ/Manchester Knees Meeting

  9. CP77 Normal Range AZ/Manchester Knees Meeting

  10. CP77 Normal Range AZ/Manchester Knees Meeting

  11. T Travellers’ L/R Knees Thickness Maps (64 × 4098)  PCA (95%) Parameters (64 × 45)  Linear Discriminant Analysis Left/Right L: Linear Discriminant Function (1 × 45)  Permutation Test: Compute true T-value; distance between classes Randomly label examples and compute T-values for each permutation AZ/Manchester Knees Meeting

  12. CP77 L/R Permutation Test AZ/Manchester Knees Meeting

  13. CP77 L/R Permutation Test AZ/Manchester Knees Meeting

  14. CP77 Further Work • Remaining Compartments • Statistical Analysis • Reproducibility • Segmentor • Sites • Left/Right Knee AZ/Manchester Knees Meeting

  15. CP78 Data • 41 Valid Patients • 2 Time Points • Bone Segmentations • Mixture of Amy and Lisa • Awaiting TP2 and complete set of TP1 • Cartilage • Mostly duplicates Amy and Lisa (+ some Yi) • SSM of 37 Lisa TP1 Bone Segmentations • shp_x37c1026i124.pdf AZ/Manchester Knees Meeting

  16. Bone/Cartilage Registration • Time-Point 1 • Chemical Shift along sagittal • Bristol 1.7 pixels • Liverpool & Manchester 2.6 pixels • Time-Point 2 • Registration of TP1 Bone Surface with TP2 Cartilage Surface • Report.pdf AZ/Manchester Knees Meeting

  17. Corresponded Thickness Maps • 4098 Correspondence Points • Mean bone Area = 15288mm2 • Coverage = 0.27 points/mm2 • Mean Separation = 1.93mm • 35 Bone surfaces (2 Time-Points) = 70 bone surfaces • -2 Poor registrations • -1 outlier • Incomplete set of Lisa cartilage segmentations • 60 Pairs of corresponded cartilage thickness measurements • 32 Amy + 28 Lisa AZ/Manchester Knees Meeting

  18. Corresponded Thickness Maps • Coverage of Thickness Measurements • readings_distribution.fig • Mean Cartilage Thickness • Meanthick.fig • Mean Cortical & Cartilage Thickness Change • Meancartdiff.fig meancortdiff.fig • Std-Dev of Thickness Changes • Stddiff.fig • Static T-Test mean(dTh) / stddev(dTh) • Ttest.fig AZ/Manchester Knees Meeting

  19. CP78 Results AZ/Manchester Knees Meeting

  20. CP78 Results AZ/Manchester Knees Meeting

  21. Statistical Analysis • N=61 Difference Thickness Maps • No cartilage = zero thickness readings • PCA • Reduce Dimensionality • Not Centred AZ/Manchester Knees Meeting

  22. Objective 1: Determine Significance by Permutation Test • In PCA space, determine Mahalanobis distance of population (non-centred) to origin; the probability of the origin being a member of the distribution: true Mahal to origin (Tdm_sumvars.fig) • For n=1000 iterations • Negate the parameters of ½ of the population • Measure Mahalanobis distance to origin • Compare permutations and true Mahalanobis distances to origin • Full Variance: 99.1% permutations closer to origin • 95% Variance: 99.9% closer • permutation_test.fig & permutation_test95.fig AZ/Manchester Knees Meeting

  23. CP78 Permutation Test AZ/Manchester Knees Meeting

  24. Objective 2: Characteristic Difference Map • Mean Difference Map • May not be characteristic (meancartdiff.fig) • PCA Modes of Variation • Illustrate trends • Variance centred on origin • Tdm_modes.fig tdm_modes2.fig • Characteristic Vector AZ/Manchester Knees Meeting

  25. TDM Modes AZ/Manchester Knees Meeting

  26. Publication Plan AZ/Manchester Knees Meeting

  27. Conferences AZ/Manchester Knees Meeting

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