Extend the model to segment also Th1 rootlets

[valosekj]

Based on a discussion during the 2025-02-06 meeting about rootlets-based registration to PAM50, it turned out that it would be relevant for the fMRI community to segment also Th1 rootlets (because fMRI data can cover this level).

IIRC, from the C2-C8 models training, we were able to see Th1 rootlets relatively well; we just decided to limit our model to C rootlets only. So, it should not be a big problem to extend the model to Th1 rootlets.
@KaterinaKrejci231054, since you've recently looked at the images when you were correcting ventral GT masks, what is your opinion? Are Th1 rootlets segmentable?

[KaterinaKrejci231054]

From my point of view, Th1 is segmentable on MP2RAGE. Rootlets are relatively well visible in all contrasts (INV1, INV2, and UNIT1). On T2w data, rootlets are even more visible in the Th1 region compared to MP2RAGE data, so it shouldn't be a problem there either.

[valosekj]

Great to hear that! It would be amazing if you included Th1 in your current model training!