I had several questions pertaining to primarily surface based tractography. Given that certain algorithms are only available in mrtrix, etc., I was wondering if either A) there is some kind of beta version of surface based tractography available (as the only command I know of that performs surface based tractography is probtrackx which is outside of mrtrix, etc.), B) if there is some means to actually convert probtrackx results to mrtrix in order to do further processing using mrtrix (e.g. for SIFT), or C) some other workaround that I just can’t seem to think of without losing what would be any gains from using surface based data (/parcellation scheme after)?
I also came across surface enhanced tractography–but I don’t think that necessarily applies in the case of a surface based parcellation scheme, unless I am incorrect?
The reason being is that I would like to use the Glasser parcellation scheme, and based on much of the literature, since it is surface-based, it appears that the current volumetric implementation of it available elsewhere for mrtrix3 would come with its own inaccuracies and be unideal. Unless there is some other workaround I am missing, I would really appreciate any advice on this situation, since it seems like this is the one aspect which would really be ideal when using mrtrix3 that seems to be not implemented yet from what I saw in the forum (I am sure there is a considerable degree of complexity needed for such an implementation).
Lastly, I was wondering what is the relative rule of thumb for using a parcellation as large as Glasser in terms of streamlines that should be generated upon running mrtrix as normal? I have seen 10^8 to 10^9 on the forum for whole brain parcellations. I would be thinking of using Glasser + the subcortical regions, and that would be a total of 379 total ROIs which are quite a bit. Does this number of streamlines that should be used depend on whether the tractography is followed by say, SIFT vs nothing at all, or is this independent?
I really appreciate any thoughts/advice!