Differences in T1w/fsaverage_LR32k surfaces between ciftify and HCP download about ciftify

[edickie]

Thanks for figuring that out! Yes, gradient distortion is something pretty specific to HCP (as it requires the gradient information that many datasets don't have available - so it was removed in ciftify. Another difference is that HCP incorporates both the T1w and the T2w data together to refine surface placement. fmriprep should do a little of this - if a T2w file is available in the BIDS directory - but I don't know if it does all the steps HCP does. ciftify was really intended for the use case when gradient distortion and T2w data in not available. Thanks, Erin

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[mharms]

Note that gradient nonlinearity correction is not a mandatory part of the HCPpipelines. It is an optional correction. And the current version of the HCPpipelines does support the situation in which no T2w scan is available.

[bwinsto2]

I realized the difference is that the HCP surfaces are based on a T1w that has undergone gradient distortion correction.

[bwinsto2]

That's true. In my case I had downloaded minimally preprocessed data from connnectomedb. Those data have all undergone GDC it seems.