This script exports imaging data from the NeuroSpin archive in BIDS format (Brain Imaging Data Structure). The BIDS format has been selected because it is simple, easy to share and supported by lots of software. We are focused on MRI data but other modalities can be added (diffusion imaging, behavioral, ...). For a full description, please consult the BIDS specification.

This script imports data, but can also:

• create ancillary files such as README, CHANGES, dataset_descrption.json
• optionally, deface anatomical data with pydeface
• run the bids-validator on the created dataset

Installation and usage

NeuroSpin installation

The neurospin_to_bids command is available on NeuroSpin workstations, where it is installed under /neurospin/local and updated nightly to the latest version.

Developer install

If you want to work on the code of neurospin_to_bids, the following method is recommended:

git clone https://github.com/neurospin/neurospin_to_bids.git

# Installation in a virtual environment
cd neurospin_to_bids
python3 -m venv venv/
. venv/bin/activate
pip install -c requirements/production.txt -c requirements/test.txt -e .[dev]

# Please install pre-commit if you intend to contribute
pre-commit install  # install the pre-commit hook

Other commands that are useful for developers:

# Tests. Always confirm that they succeed before committing. Please.

# Run tests in an isolated environment that closely approximates
# production, as well as code quality checks (recommended)
tox

pytest  # run tests in the current environment

# Other commands useful for development
./requirements/update.sh  # upgrade pinned dependency versions

# Ensure that only packages pinned for production are installed
# (beware that you will need to reinstall neuroglancer-scripts afterwards)
pip-sync requirements/production.txt

Preparation of data

Basic importation

To import data from NeuroSpin, you have to be connected to the Intra network, and the /neurospin/acquisition directory must be mounted (this is the case on all workstations configured by IT).

You have to store the information about subjects and data to import in a exp_info directory. For instance:

    ./exp_info
    ├── participants_to_import.tsv

See several small examples in test_dataset/. See also https://github.com/neurospin/unicog/tree/master/unicogfmri/localizer_pypreprocess/scripts/exp_info

Importation of data

When the exp_info directory is ready, you can launch the importation:

    cd <path_where_is_exp_info>
    neurospin_to_bids

The script is interactive. Many optional questions will be asked:

• Create or overwrite the dataset_description.json file (yes or no)
• Propose to setup the name of this dataset.
• Propose to setup a list of authors.
• Propose to setup a list of acknowledgements.
• Propose to describe how to acknowledge this dataset OR a list of publications that should be cited.
• List of sources of funding (e.g., grant numbers).
• The DOI for the dataset.
• Propose to create a README and/or CHANGES file(s).
• Deface T1 data.

The neurospin_to_bids script will export files from the NeuroSpin archive based on the information contained in the exp_info directory. The script accepts three optional arguments:

• -root_path: specifies the target folder - by default the current directory.
• -dataset_name: the folder name to export the dataset to, by default subfolder rawdata of the target folder.
• -dry-run: True/False - this mode will test the importaiton without to import data. A list of possible importation and warnings will be displayed.

If instead we were to specify the target folder (the one containing an exp_info subfolder) and a name for the BIDS dataset subfolder, we would run the command as follows:

    neurospin_to_bids -root_path some_path -dataset_name my_dataset

To read the script documentation you can write:

    neurospin_to_bids -h

Advanced importation

The importation of events are also possible if the *_events.tsv files are correctly set up. Here is an example:

    ./exp_info
    ├── participants_to_import.tsv
    └── recorded_events
        ├── export_events.py
        ├── sub-01
        │   └── ses-01
        │       └── func
        │           └── sub-01_ses-01_task-loc_events.tsv
        └── sub-02
            └── func
                └── sub-02_task-loc_events.tsv

Additional information

Basic BIDS organization

For anatomical and functional data, the bids nomenclature corresponds to the following organisation of files.

Anatomical:

    sub-<participant_label>/
        [ses-<session_label>/]
            anat/
                sub-<participant_label>[_ses-<session_label>]_T1w.nii[.gz]

Functional:

    sub-<participant_label>/
        [ses-<session_label>/]
            func/
                sub-<participant_label>[_ses-<session_label>]_task-<task_label>[_run-<run_label>]_bold.nii[.gz]

As seen by the examples, if you have a session level, a ses-<session_label> subfolder is added under the sub-<participant_label> folder and it would then be the one to contain the modality folders (here, anat or func). Moreover it should also form part of the file names.

The run level run-<run_label> is optional if there is only one functional run for a particular task.

There are plenty more optional fields to include in the file names depending on your needs. For more details on that please check directly the BIDS specifications.

Field maps:

This script has an implementation of case 4: Multiple phase encoded directions of the BIDS specification.

    sub-<participant_label>/
        [ses-<session_label>/]
            fmap/
                sub-<participant_label>[_ses-<session_label>][_acq-<label>]_dir-<label>[_run-<index>]_epi.nii[.gz]
                sub-<participant_label>[_ses-<session_label>][_acq-<label>]_dir-<label>[_run-<index>]_epi.json

Files in the exp_info folder specifying the data download

Only one file is mandatory in the exp_info directory: participants_to_import.tsv. Note that this file is not part of the BIDS standard. It is defined to contain the minimum information needed to simplify creating a BIDS dataset with the data from the NeuroSpin server.

participants_to_import.tsv

Contains information about the participants and their acquisitions. When there are multiple sessions per subject (with different acquisition dates), then the session_label column is mandatory.

    participant_id	NIP		infos_participant		session_label	acq_date	acq_label	location	to_import
    sub-01		tr070015	{"sex":"F", "age":"45"}		01		2010-06-28		trio		[['2','anat','T1w'],['9','func','task-loc_std_run-01_bold'],('10','func','task-loc_std_run-02_bold']]
    sub-02		ap100009	{"sex":"M", "age":"35"}				2010-07-01		trio		[['2','anat','T1w'],['9','func','task-loc_std_bold']]

The NIP column will only be used to identify subjects in the NeuroSpin database and will not be included in any way on the BIDS dataset to ensure proper de-identification. Moreover we recommend you to not use the NIP as the participant_label to avoid the need of future de-identification of the BIDS dataset before publication.

The participant_label and session_label are taken from this file to create the folders and file names in the BIDS dataset, every other column will be added to a new participants.tsv file included under the rawdata top folder.

The location column corresponds to the MRI used. Three labels are possible:

• 'prisma' for Prisma_fit
• 'trio' for 'database/TrioTim'
• '7t' for Investigational_Device_7T

User case with 2 sessions the same day with the same participant

For instance, if a participant undergoes an examination in the morning and in the afternoon, you have to complete the NIP with the number of session. The nip level in Neurospin is labelled as follow : '--' The examen number is automatically incremented for each new examination. Don't mange about the automatic number.

Here is an example for the participants_to_import.tsv file:

    participant_id  NIP             infos_participant               session_label   acq_date	acq_label        location        to_import
    sub-01          tt989898_6405   {"sex":"F", "age":"45"}         01              2010-06-28	      trio            [['2','anat','T1w'],['9','func','task-loc_std_run-01_bold']]
    sub-01          tt989898_6406                                	02 		        2010-06-28	      trio            [['9','func','task-loc_std_bold']]

User case for fmap importation (Multiple phase encoded directions)

Here is an example for the participants_to_import.tsv file:

    participant_id  NIP             infos_participant               session_label   acq_date	acq_label        location        to_import
    sub-01          tt989898_6405   {"sex":"F", "age":"45"}         01              2010-06-28	      prisma            [['24','anat','T1w'],['13','func','task-number_dir-ap_run-01_bold'],['14','func','task-number_dir-ap_run-01_sbref'],['5','fmap','dir-ap_epi',{'intendedFor':'/fmri/sub-301_task-number_dir-ap_run-01_bold'}]]

User case for adding a field into the json file

Here we are adding the IndendedFor field into the fmap/sub-301_dir-ap_epi.json. This field is not mandatory, but recommended. It seems if you use fmriprep, this field is not directly read and fmriprep use the **PhaseEncodingDirection" information which give by the scanner.

	participant_id  NIP     infos_participant       session_label   acq_date        acq_label       location        to_import
	sub-301 jj140402        "{""sex"":""F"", ""age"":""6""}"                2020-01-15          prisma  [['24','anat','T1w'],['13','func','task-number_dir-ap_run-01_bold'),['5','fmap','sub-301_dir-ap_epi',{'IntendedFor':'/func/task-number_dir-ap_run-01_bold'}]]

Importation of events

The importation of events can not be automatic because very often the events have to extract from log files depending on your stimulation presentation program (expyriment for python). Here we propose a possible solution, but we are truly free to import yourself into the bids_datset repository the events. The events for functional runs will be automatically copied in the BIDS dataset if the files are available in a recorded_events folder that already respect the bids structure. Which means that files would have the same fields as the bold.nii files in its file name but its final name part would be events.tsv instead, for example:

<data_root>/exp_info/recorded_events/sub-<sub_label>[/ses-<ses_label>]/func/sub-*_<task>_events.tsv

Here is an example of sub-*_<task>_events.tsv following the BIDS standard:

    onset   duration   trial_type
    0.0     1          computation_video
    2.4     1          computation_video
    8.7     1          h_checkerboard
    11.4    1          r_hand_audio
    15.0    1          sentence_audio

the onset, duration and trial_type columns are the only mandatory ones. onset and duration fields should be expressed in seconds. Other information can be added to events.tsv files such as response_time or other arbitrary additional columns respecting subject privacy. See the BIDS specification.

Deface

If you want to import data and share them with other laboratories or on an open server, you have to de-identify them. For that, the bids importation remove all fields in the header containing specific information such as "Patient's name" and the script of importation will propose to deface anatomical data. The pydeface python is used to propose this step. If you need to deface, ensure that pydeface is installed on your workstation.

Please see https://github.com/poldracklab/pydeface

Summary of importation

Files imported and warnings

A summary will be displayed at the end of importation into the terminal. The summary is also saved into ./report/download_report_*.csv file. This file is not in the rawdata repository because it is not part of BIDS.

BIDS validation

If you are selected the bids validation option, the summary is saved in ./report/report_bids_validation.txt .

Notes

• Note 1: if the importation has been interrupted or partially then, then launch again the script. The last partially downloaded data folder will be redownloaded from scratch.
• Note 2: the .tsv extension means "tabulation separated values", so each value must be separated by a tabulation and not commas, spaces or dots. If files in exp_info are not tsv, most likely the neurospin_to_bids script will fail. Please make sure your files comply with your favorite text editor.