ISMRM 2015 Tractography challenge - Discussion
The last hour of the Diffusion Study Group
of the ISMRM 2015 was dedicated to a discussion and
debate on the open questions of tractography, using insights gained
from the results of the ISMRM 2015 Tractography Challenge.
Some of the main insights that were presented include:
- Generating streamlines that are perfectly voxel-aligned to the ground-truth anatomy is really challenging, in part because of the artefacts correction process. These corrections almost always add some shift with respect to the underlying anatomy.
- The previous point can have a huge impact in a pipeline that registers multiple subjects to a common template, for example for group studies.
- Scores are much better and more realistic when using a bundle recognition technique, instead of the classical Tractometer technique, which is based on endpoints.
- Most teams found 23 of 25 Valid Bundles, at the cost of generating multiple Invalid Bundles.
- Only one submission found the 25 Valid Bundles.
- The most difficult bundles were the Anterior Commissure and the Posterior Commissure.
- The main differences between pipelines are seen in the Invalid connections and the "No connections" (streamlines not connecting 2 regions).
- There needs to be a unified tractography format, to avoid potential interaction and interpretation problems.
Please note that those results represent only a first analysis. The data provided by this challenge still holds troves of information. Further analyses will be done and communicated with the contestants and the community.