I've found an example how to read trk file with nibabel:

> import nibabel as nib
>
> track_gen, hdr = nib.trackvis.read(trk_file, as_generator=True)
>
> tracks = []
> while True:
>     try:
>         track = next(track_gen)
>     except (StopIteration, TypeError):
>         break
>     tracks.append(track)

From: freesurfer-bounces@nmr.mgh.harvard.edu [freesurfer-bounces@nmr.mgh.harvard.edu] on behalf of Peled, Noam [NPELED@mgh.harvard.edu]
Sent: Tuesday, February 16, 2016 2:16 PM
To: freesurfer@nmr.mgh.harvard.edu
Subject: [Freesurfer] path.pd.trk format

Hello,
I've noticed that in tracula 5.2 there's also a path.pd.trk file in the output directory.
How can I read this file? I would like to read the actual splines and not the probabilistic distribution in path.pd.nii.gz.

Thanks,
Noam Peled