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
Overview Interaction, geometry, exploration Anisotropy Streamtubes and streamsurfaces Anatomical landmarks Culling Discussion and conclusions
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.
Streamtubes
Streamsurfaces
Landmarks
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.
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.
Many more tubes, more obstruction, interaction slower
Many more tubes, more obstruction, interaction slower
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
Average distance between tubes in regions of dissimilarity.
Conclusions Explore entire tensor Use human visual system 3D, interaction, stereo, graphic design No hard thresholds Too much geometry
Thanks Cagatay Demiralp, Marco da Silva, Charlie Curry, Dan Morris Many visitors for feedback Susumu Mori, JHU (DT-MRI) HBP (NIDA & NIMH) NSF (CCR-0086065)
Internal Capsule
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.