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PDE methods for DWMRI Analysis and Image Registration presented by John Melonakos – NAMIC Core 1 Workshop – 31/May/2007 Outline Geodesic Tractography Review Cingulum Bundle Tractography -------------------------------------------- Fast Numerical Schemes Applications to Image Registration 2 Contributors Georgia Tech BWH John Melonakos, Vandana Mohan, Allen Tannenbaum Marc Niethammer, Kate Smith, Marek Kubicki, Martha Shenton UCI Jim Fallon 3 Publications J. Melonakos, E. Pichon, S. Angenent, A. Tannenbaum. “Finsler Active Contours”. IEEE Transactions on Pattern Analysis and Machine Intelligence. (to appear 2007). J. Melonakos, V. Mohan, M. Niethammer, K. Smith, M. Kubicki, A. Tannenbaum. “Finsler Tractography for White Matter Connectivity Analysis of the Cingulum Bundle”. MICCAI 2007. V. Mohan, J. Melonakos, M. Niethammer, M. Kubicki, A. Tannenbaum. “Finsler Level Set Segmentation for Imagery in Oriented Domains”. BMVC 2007 (in submission). Eric Pichon and Allen Tannenbaum. Curve segmentation using directional information, relation to pattern detection. In IEEE International Conference on Image Processing (ICIP), volume 2, pages 794-797, 2005. Eric Pichon, Carl-Fredrik Westin, and Allen Tannenbaum. A Hamilton-Jacobi-Bellman approach to high angular resolution diffusion tractography. In International Conference on Medical Image Computing and Computer Assisted Intervention (MICCAI), pages 180-187, 2005. 4 Directional Dependence the new length functional tangent direction This is a metric on a “Finsler” manifold if Ψ satisfies certain properties. 5 Finsler Metrics the Finsler properties: • Regularity • Positive homogeneity of degree one in the second variable • Strong Convexity Note: Finsler geometry is a generalization of Riemannian geometry. 6 Closed Curves: The Flow Derivation Computing the first variation of the functional E, the L2-optimal E-minimizing deformation is: 7 Open Curves: The Value Function Consider a seed region S½Rn, define for all target points t2Rn the value function: curves between S and t It satisfies the Hamilton-Jacobi-Bellman equation: 8 Numerics Closed Curves Level Set Techniques Open Curves Dynamic Programming (Fast Sweeping) 9 Finsler vs Riemann vs Euclid 10 Outline Geodesic Tractography Review Cingulum Bundle Tractography -------------------------------------------- Fast Numerical Schemes Applications to Image Registration 11 A Novel Approach Use open curves to find the optimal “anchor tract” connecting two ROIs Initialize a level set surface evolution on the anchor tract to capture the entire fiber bundle. 12 The Cingulum Bundle 5-7 mm in diameter “ring-like belt” around CC Involved in executive control and emotional processing 13 The Data 24 datasets from BWH (Marek Kubicki) 12 Schizophrenics 12 Normal Controls 54 Sampling Directions 14 The Algorithm Input Locating the bundle endpoints (work done by Kate Smith) 15 The Algorithm Input How the ROIs were drawn 16 Results Anterior View Posterior View 17 Results 18 Results 19 Results – A Statistical Note Attempt to sub-divide the tract to find FA significance 20 Work In Progress Implemented a level set surface evolution to capture the entire bundle – preliminary results. Working with Marek Kubicki and Jim Fallon to make informed subdivision of the bundle for statistical processing. Linking the technique to segmentation work in order to connect brain structures. 21 Outline Geodesic Tractography Review Cingulum Bundle Tractography -------------------------------------------- Fast Numerical Schemes Applications to Image Registration 22 Contributors Georgia Tech Gallagher Pryor, Tauseef Rehman, John Melonakos, Allen Tannenbaum 23 Publications T. Rehman, G. Pryor, J. Melonakos, I. Talos, A. Tannenbaum. “Multi-resolution 3D Nonrigid Registration via Optimal Mass Transport”. MICCAI 2007 workshop (in submission). T. Rehman, G. Pryor, and A. Tannenbaum. Fast Optimal Mass Transport for Dynamic Active Contour Tracking on the GPU. In IEEE Conference on Decision and Control, 2007 (in submission). G. Pryor, T. Rehman, A. Tannenbaum. BMVC 2007 (in submission). 24 Multigrid Numerical Schemes 25 Parallel Computing 26 Algorithms on the GPU 27 Parallel Computing 28 Parallel Computing 29 Outline Geodesic Tractography Review Cingulum Bundle Tractography -------------------------------------------- Fast Numerical Schemes Applications to Image Registration 30 The Registration Problem Synthetic Registration Problem 31 Solution – The Warped Grid Synthetic Registration Problem 32 The Registration Problem Before After Brain Sag Registration Problem 33 Solution – The Warped Grid 34 Speedup A 128^3 registration in less than 15 seconds 35 Key Conclusions Multigrid algorithms on the GPU can dramatically increase performance We used Optimal Mass Transport for registration, but other PDEs may also be implemented in this way 36 Questions? 37