1. NAMIC: UNC – PNL collaboration- 1 - October 7, 2005 Quantitative Analysis of Diffusion Tensor Measurements along White Matter Tracts Postdoctoral fellow, Dept of Computer Science and Psychiatry, UNC-Chapel Hill Isabelle Corouge

2. NAMIC: UNC – PNL collaboration- 2 - October 7, 2005 Diffusion Tensor MRI (DT MRI) Reveals white matter structure Gray matter White matter Courtesy of Susumu Mori, JHU DT MRI

3. NAMIC: UNC – PNL collaboration- 3 - October 7, 2005 Diffusion of Water Molecules Diffusion of water molecules From Beaulieu[02] Isotropic vs Anistropic diffusion Underlying structures of the tissues – Faster diffusion along fibers than perpendicular to them – Water diffusion anisotropy used to track fibers, estimate white matter integrity (v ,  ) (v ,  ) (v ,  ) Isotropic Diffusion v i : principal directions of diffusion i : associated diffusivities Tensor model Anisotropic Diffusion

4. NAMIC: UNC – PNL collaboration- 4 - October 7, 2005 Tensor field

5. NAMIC: UNC – PNL collaboration- 5 - October 7, 2005 Diffusion Properties Mean diffusivity (MD) Fractional anisotropy (FA) Isotropic diffusion Highly directional diffusion 0 1 Low High White matter Cerebrospinal fluid Tensor size Tensor shape

6. NAMIC: UNC – PNL collaboration- 6 - October 7, 2005 DTI Analysis in Clinical Study One concept: Region-based Analysis Co-registration of DTI Registration of DTI of each subject with: structural MRI segmentation maps lobe parcellation user-defined ROIs Statistical analysis per ROI Group 1 Group 2

7. NAMIC: UNC – PNL collaboration- 7 - October 7, 2005 Alternative Concept Quantitative Analysis of Fiber Tracts –Fiber-tract oriented analysis –Measurements across/along fiber bundles with complex geometry –Statistics of diffusion properties (FA,MD) –Statistics of tensors (non-Euclidean metric) Analysis scheme Tracking/ Clustering Selection FA FA along tract

8. NAMIC: UNC – PNL collaboration- 8 - October 7, 2005 Fiber Tracking & Clustering into Bundles Fornix cluster Longitudinal fasciculus (2312 streamlines) 6 clusters

9. NAMIC: UNC – PNL collaboration- 9 - October 7, 2005 Diffusion Properties: Adult vs Neonate Adult Neonate FA FA: Mean ± σ

10. NAMIC: UNC – PNL collaboration- 10 - October 7, 2005 Diffusion Properties: Adult vs Neonate Adult Neonate MD MD: Mean ± σ

11. NAMIC: UNC – PNL collaboration- 11 - October 7, 2005 Example: Early Brain Development Study White Matter Diffusion Corpus Callosum –Extraction and clustering of genu and splenium bundles –Measurement of diffusion properties in cross-sections along the bundles –Selection of center and left/right off-center locations

12. NAMIC: UNC – PNL collaboration- 12 - October 7, 2005 WM Diffusion of Neonates: Genu Tract DTI properties measured at midsagittal position and +/- 21 mm 21mm

13. NAMIC: UNC – PNL collaboration- 13 - October 7, 2005 White Matter Diffusion Corpus Callosum Diffusion tensor representation at the midsagittal plane and off-center (24mm along bundles). Tensors get “thinner” → less diffusivity across fibers → more structure, ev. marker for maturation Genu shows change, but not splenium 280d GestAge at MRI360d GestAge at MRI

14. NAMIC: UNC – PNL collaboration- 14 - October 7, 2005 Genu and splenium Tensor Statistics: Neonate to 1 year MD FA Neonate 1 year old Neonate 1 year old Neonate 1 year old

15. NAMIC: UNC – PNL collaboration- 15 - October 7, 2005 Tensor Statistics: Neonate to 1 year Genu Splenium

16. NAMIC: UNC – PNL collaboration- 16 - October 7, 2005 In Practice… the Tools ! FiberTracking FiberViewer

17. NAMIC: UNC – PNL collaboration- 17 - October 7, 2005 Demo Data: Brockton VA/Harvard –Case HUVA00102397 –Resampled to isotropic resolution (2x2x2mm 3 ) –Tracts: cingulate, motor, genu, splenium,…

18. NAMIC: UNC – PNL collaboration- 18 - October 7, 2005 Fiber Tracking and Fiber Viewer Easy to use and easy to learn Download: http://www.ia.unc.edu/devhttp://www.ia.unc.edu/dev Online tutorial (same url) Compatibility Slicer/FiberViewer

19. NAMIC: UNC – PNL collaboration- 19 - October 7, 2005 Acknowledgements The team –Guido Gerig (UNC) –Casey Goodlett (UNC) –Weili Lin (UNC) –Sampath Vetsa (UNC) –Tom Fletcher (Utah) –Xiadong Tao (GE) –Rémi Jean –Matthieu Jomier (France) –Sylvain Gouttard (France) –Clément Vachet (France) Software development –ITK, VTK, Qt –Julien Jomier (UNC)