1. Song Zhang, David Laidlaw Brown University Computer Science
Elucidating Neural Structure in DT-MRI Volumes Using Streamtubes and Streamsurfaces
Song Zhang, David Laidlaw
Brown University Computer Science

2. Overview Interaction, geometry, exploration Anisotropy
Streamtubes and streamsurfaces
Anatomical landmarks
Culling
Discussion and conclusions

3. Anisotropy metrics(Westin et al)
Linear anisotropy
Planar anisotropy
Isotropy(Not visualized)
In our method, we try to distinguish linear anisotropy and planar anisotropy, that is, our anisotropy metric should be direction dependent. Thus, we can’t use Rational anisotropy or Fractional anisotropy, cause they are directionless, they won’t tell the difference between linear and planar anisotropy. Intuitively, we use the difference of the first 2 eigenvalues for the metric for linear anisotropy, and difference between 2nd and 3rd eigenvalues for metrics for planar anisotropy. We set a threshold alpha and beta to determine whether a certain sample has linear anisotropy or planar anisotropy.

4. Streamtubes

6. Streamsurfaces

7. Landmarks

10. Culling Reduce 1.2M to 472 Anisotropy threshold (>0.20)
Avg. anisotropy (>0.30)
Tube length (>18.0mm)
Tube similarity (>4.5mm)
Noise distance threshold (<0.9mm)
Average distance between tubes in regions of dissimilarity.

12. Culling Reduce 1.2M to 4,538 (was 472) Anisotropy threshold > 0.20
Average anisotropy > 0.20 (was 0.30)
Tube length > 4.5mm (was 18.0mm)
Tube similarity > 1.8mm (was 4.5mm)
Average distance between tubes in regions of dissimilarity.

13. Many more tubes, more obstruction, interaction slower

14. Many more tubes, more obstruction, interaction slower

15. Applications Exploration of DT-MRI data Preoperative surgical planning
Longitudinal changes
Beyond video – immersive virtual reality
Only way to image white matter tracts
Changes due to development or pathology

16. Average distance between tubes in regions of dissimilarity.

17. Conclusions Explore entire tensor Use human visual system
3D, interaction, stereo, graphic design
No hard thresholds
Too much geometry

18. Thanks Cagatay Demiralp, Marco da Silva, Charlie Curry, Dan Morris
Many visitors for feedback
Susumu Mori, JHU (DT-MRI)
HBP (NIDA & NIMH)
NSF (CCR )

23. Internal Capsule

25. Culling Reduce 150,000 to several thousand
Anisotropy threshold (>0.20)
Tube length (>20mm)
Tube similarity (>45mm)
Average distance between tubes in regions of dissimilarity.