Research update Atlas Building in DTI Rémi Jean Casey Goodlett Guido Gerig
Project • Atlas building in DTI • Atlas based on FA images • Atlas based on tensor fields Casey Goodlett, Brad Davis, Remi Jean, John Gilmore, Guido GerigImproved Correspondence for DTI Population Studies via Unbiased Atlas Building • Do studies using atlas
What’s an Atlas ? • Atlas: Average and variability of a population of images • Applications: Segmentation, population characterization Image 1 Deformations Atlas Image n
Previous work • Atlas based on FA images • 5 1 year old and 10 neonates • Possibility to transform fiber bundles: Atlas space <-> Image space
FA FA FA’’ warped Atlas of FA Transformations The pipeline Affine Transformation FA’’ FA’’ affined Fluid Deformation Averaging
Is it a good way to build an atlas ? • Diffusion Tensor Imaging • More information in tensorfields : scale, orientation • By working on the tensors, we expect more accurate results
Atlas (Affine, Fluid) Structural Operator Structural Average DTI Images (1:N) Scalar Images From Manifold Detector on FA H-fields (1:N) H-1-fields (1:N) New approach : tensors 1 step :: Registration
DTI Images Rotate Tensors based on JH-1 Tensor Averaging DTI Atlas H-fields (1:N) Riemannian Symmetric Space New approach : tensors 2 step :: Atlas formation
Full tracts On- and off-center regions Bundles obtained from 50 cases atlas by tractography
Results : DTI atlas building Old method: Trackings in 50 individual images New method: One tracking in the atlas and statistical analysis across population • Smaller variability across subjects. • FA seems lower due to smoothing of data, but separability of clusters is much better, and thus discrimination. • New method is very efficient (2months versus a few hours user time if atlas is built).
Results Neonate - 59 cases 1 year old - 25 cases 2 years old - 13 cases
Current and future work • 1 year old atlas with 90 cases • 60 Controls • 20 Schizophrenics • 10 MVM cases • Create an automatic pipeline to compute an atlas • Batchmake
Future work • Do statistics on the 90 cases atlas • Compare the different populations • Figure out how to compare the different atlases ? • And how to map new cases into the atlas ?
Thank you • Questions ?