Enhancement: Add Euler number metric to structural QA report

[jvarada]

https://www.biorxiv.org/content/early/2017/10/01/125161

[chrisgorgo]

To calculate this metric one would have to run full recon-all from FreeSurfer. That would add 8-12h per scan, which might be just too much for most users.

[jvarada]

@chrisfilo Perhaps run it with an optional tag, rather than by default, like the ICA workflow?

[chrisgorgo]

Yes that could work. Or providing already calculated FreeSurfer directory.

Perhaps it might be worthwhile exposing this variable in FMRIPREP reports.

[stale[bot]]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[oesteban]

Moving this to fMRIPrep, where it could see an implementation one day.