Dear Freesurfer community,

I'm trying to extract labels from a .gca atlas volume using the following command:

mri_convert atlas.gca -nth 1 labels.mgz (from https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial/GcaFormat)

I've found a .gca file in the /average folder for which this works (RB_all_2020-01-02.gca), but for the cortical parcellations I'm actually interested in (e.g. lh.DKTatlas40.gcs), I get the following error:

I'm pretty confused, because the documentations, as well as other support requests, are pretty clear on that my problem should be solved using the mentioned command. Notably, mri_convert -u, does not list GCA under the supported file-types, maybe this is a versioning issue?

I'm using freesurfer 7.2.0 with Ubunutu 22.04.4.

Any help is much appreciated.

Best regards,

Nys Tjade Siegel