This document summarizes a study on developing a probabilistic tractography and segmentation method to chart the human thalamus. The study used diffusion tensor imaging and probabilistic tractography to visualize cortico-thalamic connections. It then developed a statistical shape model of the mean thalamus atlas incorporating these connectivity maps. The method was able to align the atlas to individual subjects' geometry with sub-millimeter accuracy, outperforming conventional alignment methods. This individualized target mapping method could help guide image-guided neurosurgery of the thalamus.

4. Donnerstag, 20. Oktober 2011

6. What really causes anisotropic diffusion? Beaulieu C. The basis of anisotropic water diffusion in the nervous system - a technical review. NMR Biomed 2002;15:435-455 .

7. Diffusion weighted imaging 1. B0 image 2. DWI image(s) 3. ADCx,y,z… 4. ADC (average)

8. Donnerstag, 20. Oktober 2011 Departement/Institut/Gruppe

9. Diffusion tensor imaging

12. Deterministic fiber tracking: art or science?

13. Deterministic fiber tracking: art or science?

14. Deterministic fiber tracking: art or science? Right handed Left handed NeuroImage 35 (2007) 1064–1076

16. Tracking neuronal pathways: other solutions

19. Further implications of probabilistic tracking Behrens et al. Non-invasive mapping of connections between human thalamus and cortex using diffusion imaging Nature Neuroscience 6 , 750 - 757 (2003) Jakab et al. Connectivity-based parcellation reveals interhemispheric differences in the insula Brain Topography – in press - (2011) “ Based on connection targets” “ Clustering based on similarities of connectome”

20. Donnerstag, 20. Oktober 2011 Departement/Institut/Gruppe MTT Sat., Gringel et al. 2009 7T T1-w Zürich Morel et al. 1997 fMRI - Hulme et al. 2010 DTI+SSM Atlas- Jakab et al. 2011?

22. State of the art imaging of the thalamus with DTI Donnerstag, 20. Oktober 2011 D-ITET / COMPUTER VISION LABORATORY Diffusion tensor imaging and probabilistic tractography visualizes cortico-thalamic connections Top right images> Behrens et al. Non-invasive mapping of connections between human thalamus and cortex using diffusion imaging Nature Neuroscience 6 , 750 - 757 (2003) Clinical, 1.5T 3DT1 Gross, structural information

26. Donnerstag, 20. Oktober 2011 Departement/Institut/Gruppe

27. Biological correspondence: regions defined by Atlas vs. connectivity

28. Biological correspondence: regions defined by Atlas vs. connectivity

29. Biological correspondence: regions defined by Atlas vs. connectivity

31. Cortico-thalamic connections depicted using probabilistic tractography. Points represent the center-of-gravities of each connectivity map. Axial (top) view, isometric 3d display.

32. Connections of the precentral and postcentral gyrus and the spatial relationship between connectivity-based landmarks and the MNI152-transformed Morel Atlas data (VLpv, VPLa, VPLp nuclei). Points represent the center-of-gravities of each connectivity map. Superior view, isometric 3d display.

33. Results – aligned maps and intrathalamic landmarks Donnerstag, 20. Oktober 2011 D-ITET / COMPUTER VISION LABORATORY Black outlines: SSM-matched thalamus atlas Red spot: somatosensory connections, VPL

34. Results – Comparison to ACPC matching Donnerstag, 20. Oktober 2011 D-ITET / COMPUTER VISION LABORATORY Blue: SSM-based target map Red: ACPC aligned thalamus atlas Comparison on 1.5 T clinical imaging and CORTICOTHALAMIC TRACTOGRAPHY VL nucleus (VLa, VLpv) Somatomotor connections Somatomotor connections

35. Results – Comparison to ACPC matching Donnerstag, 20. Oktober 2011 D-ITET / COMPUTER VISION LABORATORY Blue: SSM-based target map Red: ACPC aligned thalamus atlas Comparison on 7.0 T post mortem imaging CENTROMEDIAN NUCLEUS

36. Testing of the outline-based method: postmortem images

37. Testing of the outline-based method: postmortem images

38. Testing of the outline-based method: postmortem images

39. Testing of the outline-based method: postmortem images

40. Results – spatial accuracy (quantitative) Donnerstag, 20. Oktober 2011 D-ITET / COMPUTER VISION LABORATORY Name of the structure tested Alignment method Mean distance (mm) Median distance (mm) Thalamus outline ACPC reg. with scaling 1.44 ± 0.44 1.24 ± 0.44 Thalamus outline Rigid reg. of surface 1.16 ± 0.11 1.07 ± 0.13 Thalamus outline SSM matching of outline 0.83 ± 0.1 0.56 ± 0.09 Thalamus outline Hybrid SSM matching (internal landmarks) 1.07 ± 0.18 0.83 ± 0.17 Postmortem nuclei (AV, MDmc, MDpc) SSM matching of outline 0.79 ± 0.22 0.59 ± 0.14

41. An application – MRgFUS targeting Donnerstag, 20. Oktober 2011 D-ITET / COMPUTER VISION LABORATORY Individual target volume adapted to individual geometry, after segmentation of iMRI image.