[ENH] Add example dataset for MRI chunk entity

[valosekj]

This PR adds an example dataset for the MRI chunk entity.

The "chunk" entity is added to the MRI datatype in bids-standard/bids-specification#1586.

Note that I intentionally did not truncate the data to preserve its nifti header with qforms for different chunks (FOVs). Instead, I created empty masks of the original images --> images are empty, but the nifti header has been preserved.

[effigies]

Please truncate the NIfTI files to headers.

zcat img.nii.gz | head -c 352 | gzip - | sponge img.nii.gz

[valosekj]

Please truncate the NIfTI files to headers.

zcat img.nii.gz | head -c 352 | gzip - | sponge img.nii.gz

Thanks! Done in 6a84c8f

[Remi-Gau]

Could you update the dataset listing?

https://github.com/bids-standard/bids-examples/blob/master/CONTRIBUTING.md#how-to-generate-the-tables-in-the-readme

It is in the root of the repo:
https://github.com/bids-standard/bids-examples/blob/master/dataset_listing.tsv

Ideally it should link to where the "real" data is: may be quite useful in this case

[valosekj]

Could you update the dataset listing?

https://github.com/bids-standard/bids-examples/blob/master/CONTRIBUTING.md#how-to-generate-the-tables-in-the-readme

It is in the root of the repo: https://github.com/bids-standard/bids-examples/blob/master/dataset_listing.tsv

Done in ec44bc3.

Ideally it should link to where the "real" data is: may be quite useful in this case

Unfortunately, the dataset is not publicly available. And I am not aware of any public MRI dataset with "chunks".

[Remi-Gau]

Unfortunately, the dataset is not publicly available. And I am not aware of any public MRI dataset with "chunks".

OK let's keep like that for now but it would be good in the future to be able to point to a real one.

[valosekj]

Since the corresponding PR has been merged, maybe this PR could be merged as well?

[Remi-Gau]

I think this will have to wait for the BIDS validator to be changed to accept this new entity