bidscoin 2.1

Converts and organises raw MRI data-sets according to the Brain Imaging Data Structure (BIDS)

BIDScoin

• The BIDScoin workflow
• The BIDScoin tools
  • Running the bidsmapper
  • Running the bidseditor
  • Running the bidscoiner
• The bidsmap files
  • Tips and tricks
    • Attribute list
    • Dynamic values
    • Field maps: IntendedFor
    • Plug-in functions
• BIDScoin functionality / TODO
• BIDScoin tutorial

BIDScoin is a user friendly open-source python toolkit that converts ("coins") source-level (raw) neuroimaging data-sets to nifti / json / tsv data-sets that are organized following the Brain Imaging Data Structure, a.k.a. BIDS standard. Rather then depending on complex or ambiguous programmatic logic for the identification of imaging modalities, BIDScoin uses a direct mapping approach to identify and convert the raw source data into BIDS data. The information sources that can be used to map the source data to BIDS are:

1. Information in MRI header files (DICOM, PAR/REC or .7 format; e.g. SeriesDescription)
2. Information from nifti headers (e.g. image dimensionality)
3. Information in the file structure (file- and/or directory names, e.g. number of files)

NB: Currently, the DICOM support (option 1) has been fully implemented, but the support for option 2 and 3 is planned for future releases.

The mapping information is stored as key-value pairs in the human readable and widely supported YAML files. The nifti- and json-files are generated with dcm2niix. In addition, users can provide custom written plug-in functions, e.g. for using additional sources of information or e.g. for parsing of Presentation logfiles.

Because all the mapping information can be edited with a graphical user interface, BIDScoin requires no programming knowledge in order to use it.

For information on the BIDScoin installation and requirements, see the installation guide.

The BIDScoin workflow

Required source data structure

BIDScoin will take your (raw) source data as well as a YAML file with the key-value mapping (dictionary) information as input, and returns a BIDS folder as output. The source data input folder should be organised according to a /sub-identifier/[ses-identifier]/seriesfolder/dicomfile structure. This data organization is how users receive their data from the (Siemens) scanners at the DCCN (NB: the ses-identifier sub-folder is optional and can be left out).

• If your data is not already organized in this way, you can use the handy dicomsort.py command-line utility to move your unordered or DICOMDIR ordered DICOM-files into a seriesfolder organization with the DICOM series-folders being named [SeriesNumber]-[SeriesDescription]. Series folders contain a single data type and are typically acquired in a single run.

• Another command-line utility that can be helpful in organizing your source data is rawmapper.py. This utility can show you the overview (map) of all the values of DICOM-fields of interest in your data-set and, optionally, use these fields to rename your source data sub-folders (this can be handy e.g. if you manually entered subject-identifiers as [Additional info] at the scanner console and you want to use these to rename your subject folders).

If these utilities do not satisfy your needs, then have a look at this reorganize_dicom_files tool.

Coining your source data to BIDS

Having an organized source data folder, the actual data-set conversion to BIDS can be performed fully automatically by simply running 1) the bidsmapper.py, 2) the bidseditor.py and 3) the bidscoiner.py command-line tools after another:

Step 1: Running the bidsmapper

usage: bidsmapper.py [-h] [-t TEMPLATE] [-n SUBPREFIX] [-m SESPREFIX]
                     sourcefolder bidsfolder

Creates a bidsmap.yaml YAML file in the bidsfolde/code that maps the information from
all raw source data to the BIDS labels. You can check and edit the bidsmap file with
the bidseditor (but also with any text-editor) before passing it to the bidscoiner.
N.B.: Institute users may want to use a site-customized template bidsmap (see the
--bidsmap option).

positional arguments:
  sourcefolder          The source folder containing the raw data in
                        sub-#/ses-#/series format (or specify --subprefix and
                        --sesprefix for different prefixes)
  bidsfolder            The destination folder with the (future) bids data and
                        the default bidsfolder/code/bidsmap.yaml file

optional arguments:
  -h, --help            show this help message and exit
  -t TEMPLATE, --template TEMPLATE
                        The non-default / site-specific template file with the
                        BIDS heuristics
  -n SUBPREFIX, --subprefix SUBPREFIX
                        The prefix common for all the source subject-folders.
                        Default: 'sub-'
  -m SESPREFIX, --sesprefix SESPREFIX
                        The prefix common for all the source session-folders.
                        Default: 'ses-'

examples:
  bidsmapper.py /project/foo/raw /project/foo/bids
  bidsmapper.py /project/foo/raw /project/foo/bids -t bidsmap_dccn

Step 2: Running the bidseditor

usage: bidseditor.py [-h] [-s SOURCEFOLDER] [-b BIDSMAP] [-t TEMPLATE]
                     bidsfolder

This tool launches a graphical user interface for editing the bidsmap.yaml file
that is e.g. produced by the bidsmapper or by this bidseditor itself. The user can
fill in or change the BIDS labels for entries that are unidentified or sub-optimal,
such that meaningful BIDS output names will be generated from these labels. The saved
bidsmap.yaml output file can be used for converting the source data to BIDS using
the bidscoiner.

positional arguments:
  bidsfolder            The destination folder with the (future) bids data

optional arguments:
  -h, --help            show this help message and exit
  -s SOURCEFOLDER, --sourcefolder SOURCEFOLDER
                        The source folder containing the raw data. If empty,
                        it is derived from the bidsmap provenance information
  -b BIDSMAP, --bidsmap BIDSMAP
                        The bidsmap YAML-file with the study heuristics. If
                        the bidsmap filename is relative (i.e. no "/" in the
                        name) then it is assumed to be located in
                        bidsfolder/code/. Default: bidsmap.yaml
  -t TEMPLATE, --template TEMPLATE
                        The bidsmap template with the default heuristics (this
                        could be provided by your institute). If the bidsmap
                        filename is relative (i.e. no "/" in the name) then it
                        is assumed to be located in bidsfolder/code/. Default:
                        bidsmap_template.yaml

examples:
  bidseditor.py /project/foo/bids
  bidseditor.py /project/foo/bids -t bidsmap_dccn.yaml
  bidseditor.py /project/foo/bids -b my/custom/bidsmap.yaml

Here are a few tips & tricks:
-----------------------------

DICOM Attributes
  An (DICOM) attribute label can also be a list, in which case the BIDS labels / mapping
  are applies if a (DICOM) attribute value is in this list. If the attribute value is
  empty it is not used to identify the series. Example: SequenceName: [epfid2d1rs, '*fm2d2r']

Dynamic BIDS labels
  The BIDS labels can be static, in which case the label is just a normal string, or dynamic,
  when the string is enclosed with pointy brackets like `<attribute name>` or
  `<<argument1><argument2>>`. In case of single pointy brackets the label will be replaced
  during bidsmapper, bidseditor and bidscoiner runtime by the value of the (DICOM) attribute
  with that name. In case of double pointy brackets, the label will be updated for each
  subject/session during bidscoiner runtime. For instance, then the `run` label `<<1>>` in
  the bids name will be replaced with `1` or increased to `2` if a file with runindex `1`
  already exists in that directory.

Field maps: IntendedFor
  You can use the `IntendedFor` field to indicate for which runs (DICOM series) a fieldmap
  was intended. The dynamic label of the `IntendedFor` field can be a list of string patterns
  that is used to include all runs in a session that have that string pattern in their BIDS
  file name. Example: use `<<task>>` to include all functional runs or `<<Stop*Go><Reward>>`
  to include "Stop1Go"-, "Stop2Go"- and "Reward"-runs.

Manual editing / inspection of the bidsmap
  You can of course also directly edit or inspect the `bidsmap.yaml` file yourself with any
  text editor. For instance to change the `Options` to your needs or to add a dynamic
  `participant_label` value like `<<PatientID>>`. See ./docs/bidsmap.md for more information.

As shown below, the main window of the bidseditor opens with the BIDS map tab that contains a list of input samples that uniquely represents all the different files that are present in the source folder, together with the associated BIDS output name. The name of the BIDS modality folder is shown in red if the modality is not part of the BIDS standard, otherwise it is colored green. Double clicking the sample (DICOM) filename opens an inspection window with the full header information (double clicking sample filenames works throughout the GUI). The user can click the Edit button for each list item to open a new edit window.

Shown below, in the edit window the user can choose the right BIDS Modality (drop down menu) and edit the associated BIDS Labels (double click black items), or (for expert usage) adapt the DICOM Attributes (double click black items). The new BIDS Output name is then shown on the bottom and, if it is all fine, the user can copy it over to the main window by clicking the OK button.

If all BIDS output names in the main window are fine, the user can click on the Save button and proceed with running the bidscoiner tool.

Step 3: Running the bidscoiner

usage: bidscoiner.py [-h] [-p PARTICIPANT_LABEL [PARTICIPANT_LABEL ...]] [-f]
                     [-s] [-b BIDSMAP] [-n SUBPREFIX] [-m SESPREFIX] [-v]
                     sourcefolder bidsfolder

Converts ("coins") datasets in the sourcefolder to nifti / json / tsv datasets in the
bidsfolder according to the BIDS standard. Check and edit the bidsmap.yaml file to
your needs using the bidseditor.py tool before running this function. You can run
bidscoiner.py after all data is collected, or whenever new data has been added to the
source folder (presuming the scan protocol hasn't changed).

Provenance information, warnings and error messages are stored in the 
bidsfolder/code/bidscoiner.log file.

positional arguments:
  sourcefolder          The source folder containing the raw data in
                        sub-#/[ses-#]/series format (or specify --subprefix
                        and --sesprefix for different prefixes)
  bidsfolder            The destination / output folder with the bids data

optional arguments:
  -h, --help            show this help message and exit
  -p PARTICIPANT_LABEL [PARTICIPANT_LABEL ...], --participant_label PARTICIPANT_LABEL [PARTICIPANT_LABEL ...]
                        Space seperated list of selected sub-# names / folders
                        to be processed (the sub- prefix can be removed).
                        Otherwise all subjects in the sourcefolder will be
                        selected
  -f, --force           If this flag is given subjects will be processed,
                        regardless of existing folders in the bidsfolder.
                        Otherwise existing folders will be skipped
  -s, --skip_participants
                        If this flag is given those subjects that are in
                        particpants.tsv will not be processed (also when the
                        --force flag is given). Otherwise the participants.tsv
                        table is ignored
  -b BIDSMAP, --bidsmap BIDSMAP
                        The bidsmap YAML-file with the study heuristics. If
                        the bidsmap filename is relative (i.e. no "/" in the
                        name) then it is assumed to be located in
                        bidsfolder/code/. Default: bidsmap.yaml
  -n SUBPREFIX, --subprefix SUBPREFIX
                        The prefix common for all the source subject-folders.
                        Default: 'sub-'
  -m SESPREFIX, --sesprefix SESPREFIX
                        The prefix common for all the source session-folders.
                        Default: 'ses-'
  -v, --version         Show the BIDS and BIDScoin version

examples:
  bidscoiner.py /project/foo/raw /project/foo/bids
  bidscoiner.py -f /project/foo/raw /project/foo/bids -p sub-009 sub-030

Finishing up

After a successful run of bidscoiner.py, the work to convert your data in a fully compliant BIDS dataset is unfortunately not yet fully over and, depending on the complexity of your data-set, additional tools may need to be run and meta-data may need to be entered manually (not everything can be automated). For instance, you should update the content of the dataset_description.json and README files in your bids folder and you may need to provide e.g. additional *_scans.tsv,*_sessions.tsv or participants.json files (see the BIDS specification for more information). Moreover, if you have behavioural log-files you will find that BIDScoin does not (yet) support converting these into BIDS compliant *_events.tsv/json files (advanced users are encouraged to use the bidscoiner.py plug-in possibility and write their own log-file parser).

If all of the above work is done, you can (and should) run the web-based bidsvalidator to check for inconsistencies or missing files in your bids data-set (NB: the bidsvalidator also exists as a command-line tool).

NB: The provenance of the produced BIDS data-sets is stored in the bids/code/bidscoiner.log file. This file is also very useful for debugging / tracking down bidsmapping issues.

Plug-in functions

BIDScoin provides the possibility for researchers to write custom python functions that will be executed at bidsmapper.py and bidscoiner.py runtime. To use this functionality, enter the name of the module (default location is the plugins-folder; otherwise the full path must be provided) in the bidsmap dictionary file to import the plugin functions. The functions in the module should be named "bidsmapper_plugin" for bidsmapper.py and "bidscoiner_plugin" for bidscoiner.py. See README.py for more details and placeholder code.

BIDScoin functionality / TODO

• DICOM source data
• PAR / REC source data
• P7 source data
• Nifti source data
• Fieldmaps
• Multi-echo data
• Multi-coil data
• PET data
• Stimulus / behavioural logfiles

Are you a python programmer with an interest in BIDS who knows all about GE and / or Philips data? Are you experienced with parsing stimulus presentation log-files? Or do you have ideas to improve the this toolkit or its documentation? Have you come across bugs? Then you are highly encouraged to provide feedback or contribute to this project on https://github.com/Donders-Institute/bidscoin.

BIDScoin tutorial

This tutorial is specific for researchers from the DCCN and makes use of data-sets stored on its central file-system. However, it should not be difficult to use (at least part of) this tutorial for other data-sets as well.

1. Preparation. Activate the bidscoin environment and create a tutorial playground folder in your home directory by executing these bash commands (see also module help bidscoin):

   module add bidscoin  
   source activate /opt/bidscoin  
   cp -r /opt/bidscoin/tutorial ~
   

   The new tutorial folder contains a raw source-data folder and a bids_ref reference BIDS folder, i.e. the end product of this tutorial.

   Let's begin with inspecting this new raw data collection:

   • Are the DICOM files for all the sub-*/ses-# folders organised in series-subfolders (e.g. sub-001/ses-01/003-T1MPRAGE/0001.dcm etc)? Use dicomsort.py if not
   • Use the rawmapper.py command to print out the DICOM values of the "EchoTime", "Sex" and "AcquisitionDate" of the fMRI series in the raw folder

2. BIDS mapping. Scan all folders in the raw data collection for unknown data by running the bidsmapper bash command:

   bidsmapper.py raw bids
   

3. BIDS editing. Edit your bidsmap.yaml file by running the bidseditor bash command:

   bidseditor.py bids
   

   • Rename the "task_label" of the functional scans into something more readable, e.g. "Reward" and "Stop"
   • Add a search pattern to the IntendedFor field such that it will select your fMRI runs
   • When done, open the bidsmap.yaml file and change the options such that you will get non-zipped nifti data (i.e. *.nii instead of *.nii.gz) in your BIDS data collection

4. BIDS coining. Convert your raw data collection into a BIDS collection by running the bidscoiner bash command (note that the input is the same as for the bidsmapper):

   bidscoiner.py raw bids
   

   • Check your bids/code/bidscoiner.log file for any errors or warnings
   • Compare the results in your bids/sub-# subject folders with the in bids_ref reference result. Are the file and foldernames the same? Also check the json sidecar files of the fieldmaps. Do they have the right "EchoTime" and "IntendedFor" fields?
   • What happens if you re-run the bidscoiner.py command? Are the same subjects processed again? Re-run "sub-001".
   • Inspect the bids/participants.tsv file and decide if it is ok.
   • Update the dataset_description.json and README files in your bids folder
   • As a final step, run the bids-validator on your ~/bids_tutorial folder. Are you completely ready now to share this dataset?