Note
Go to the end to download the full example code.
13. Anonymizing a BIDS dataset#
Consider the following scenario:
You’ve created a BIDS dataset.
Now you want to make this dataset available to the public.
Therefore, all personally identifying information must be removed.
While mne_bids.write_raw_bids()
and mne_bids.write_anat()
can be
used to store anonymized copies of data (by passing the anonymize
and
deface
keyword arguments, respectively), using these functions to anonymize
an entire existing dataset can be cumbersome and error-prone.
MNE-BIDS provides a dedicated function, mne_bids.anonymize_dataset()
,
to do the heavy lifting for you, automatically.
# Authors: The MNE-BIDS developers
# SPDX-License-Identifier: BSD-3-Clause
import shutil
import mne
from mne_bids import (
BIDSPath,
anonymize_dataset,
print_dir_tree,
write_anat,
write_meg_calibration,
write_meg_crosstalk,
write_raw_bids,
)
data_path = mne.datasets.sample.data_path()
event_id = {
"Auditory/Left": 1,
"Auditory/Right": 2,
"Visual/Left": 3,
"Visual/Right": 4,
"Smiley": 5,
"Button": 32,
}
raw_path = data_path / "MEG" / "sample" / "sample_audvis_raw.fif"
raw_er_path = data_path / "MEG" / "sample" / "ernoise_raw.fif" # empty-room
events_path = data_path / "MEG" / "sample" / "sample_audvis_raw-eve.fif"
cal_path = data_path / "SSS" / "sss_cal_mgh.dat"
ct_path = data_path / "SSS" / "ct_sparse_mgh.fif"
t1w_path = data_path / "subjects" / "sample" / "mri" / "T1.mgz"
bids_root = data_path.parent / "MNE-sample-data-bids"
bids_root_anon = data_path.parent / "MNE-sample-data-bids-anon"
To ensure the output paths don’t contain any leftover files from previous tests and example runs, we simply delete it.
Warning
Do not delete directories that may contain important data!
bids_path = BIDSPath(
subject="ABC123", task="audiovisual", root=bids_root, datatype="meg"
)
bids_path_er = bids_path.copy().update(
subject="emptyroom", task="noise", session="20021206"
)
raw = mne.io.read_raw_fif(raw_path, verbose=False)
raw_er = mne.io.read_raw_fif(raw_er_path, verbose=False)
# specify power line frequency as required by BIDS
raw.info["line_freq"] = 60
raw_er.info["line_freq"] = 60
# Write empty-room data
write_raw_bids(raw=raw_er, bids_path=bids_path_er, verbose=False)
# Write experimental MEG data, fine-calibration and crosstalk files
write_raw_bids(
raw=raw,
bids_path=bids_path,
events=events_path,
event_id=event_id,
empty_room=bids_path_er,
verbose=False,
)
write_meg_calibration(cal_path, bids_path=bids_path, verbose=False)
write_meg_crosstalk(ct_path, bids_path=bids_path, verbose=False)
# Write anatomical scan
# We pass the MRI landmark coordinates, which will later be required for
# automated defacing
mri_landmarks = mne.channels.make_dig_montage(
lpa=[66.08580, 51.33362, 46.52982],
nasion=[41.87363, 32.24694, 74.55314],
rpa=[17.23812, 53.08294, 47.01789],
coord_frame="mri_voxel",
)
bids_path.datatype = "anat"
write_anat(image=t1w_path, bids_path=bids_path, landmarks=mri_landmarks, verbose=False)
BIDSPath(
root: /home/circleci/mne_data/MNE-sample-data-bids
datatype: anat
basename: sub-ABC123_T1w.nii.gz)
Basic anonymization#
Now we’re ready to anonymize the dataset!
anonymize_dataset(bids_root_in=bids_root, bids_root_out=bids_root_anon)
Anonymizing BIDS dataset
Determining "daysback" for anonymization.
Input: /home/circleci/mne_data/MNE-sample-data-bids
Output: /home/circleci/mne_data/MNE-sample-data-bids-anon
Shifting recording dates by 31403 days (86.0 years).
Using the following subject ID anonymization mapping:
sub-ABC123 → sub-1
sub-emptyroom → sub-emptyroom
0%| | Anonymizing : 0/5 [00:00<?, ?it/s]
20%|██ | Anonymizing : 1/5 [00:00<00:01, 2.55it/s]
60%|██████ | Anonymizing : 3/5 [00:01<00:00, 2.53it/s]
100%|██████████| Anonymizing : 5/5 [00:03<00:00, 1.44it/s]
100%|██████████| Anonymizing : 5/5 [00:03<00:00, 1.46it/s]
That’s it! Let’s have a look at directory structure of the anonymized dataset.
|MNE-sample-data-bids-anon/
|--- README
|--- dataset_description.json
|--- participants.json
|--- participants.tsv
|--- sub-1/
|------ sub-1_scans.tsv
|------ anat/
|--------- sub-1_T1w.json
|--------- sub-1_T1w.nii.gz
|------ meg/
|--------- sub-1_acq-calibration_meg.dat
|--------- sub-1_acq-crosstalk_meg.fif
|--------- sub-1_coordsystem.json
|--------- sub-1_task-audiovisual_channels.tsv
|--------- sub-1_task-audiovisual_events.json
|--------- sub-1_task-audiovisual_events.tsv
|--------- sub-1_task-audiovisual_meg.fif
|--------- sub-1_task-audiovisual_meg.json
|--- sub-emptyroom/
|------ ses-19161214/
|--------- sub-emptyroom_ses-19161214_scans.tsv
|--------- meg/
|------------ sub-emptyroom_ses-19161214_task-noise_channels.tsv
|------------ sub-emptyroom_ses-19161214_task-noise_meg.fif
|------------ sub-emptyroom_ses-19161214_task-noise_meg.json
You can see that the subject ID was changed to a number (in this case, the
digit 1`
), and the recording dates have been shifted backward in time (as
indicated by the emptyroom
session name). Anonymized IDs are zero-padded
numbers ranging from 1 to \(N\), where \(N\) is the total number of
participants (excluding the emptyroom
pseudo-subject).
Limiting to specific data types#
By default, mne_bids.anonymize_dataset()
will anonymize
electrophysiological data and anatomical MR scans (T1-weighted and FLASH).
You can limit which data types to convert using the datatypes
keyword
argument. The parameter can be a string (e.g., 'meg'
, 'eeg'
,
'anat'
) or a list of such strings.
shutil.rmtree(bids_root_anon)
anonymize_dataset(
bids_root_in=bids_root,
bids_root_out=bids_root_anon,
datatypes="anat", # Only anatomical data
)
print_dir_tree(bids_root_anon)
Anonymizing BIDS dataset
Input: /home/circleci/mne_data/MNE-sample-data-bids
Output: /home/circleci/mne_data/MNE-sample-data-bids-anon
Not shifting recording dates (found anatomical scans only).
Using the following subject ID anonymization mapping:
sub-ABC123 → sub-1
sub-emptyroom → sub-emptyroom
0%| | Anonymizing : 0/1 [00:00<?, ?it/s]
100%|██████████| Anonymizing : 1/1 [00:02<00:00, 2.13s/it]
100%|██████████| Anonymizing : 1/1 [00:02<00:00, 2.13s/it]
|MNE-sample-data-bids-anon/
|--- README
|--- dataset_description.json
|--- participants.json
|--- sub-1/
|------ anat/
|--------- sub-1_T1w.json
|--------- sub-1_T1w.nii.gz
Specifying time shift#
Anonymization involves shifting the recording dates back in time. MNE-BIDS
will try to automatically choose a suitable time shift. You may also
explicitly specify by how many days you wish to shift the recording dates
back in time via the daysback
parameter. To avoid the time shift, pass
daysback=0
.
shutil.rmtree(bids_root_anon)
anonymize_dataset(
bids_root_in=bids_root,
bids_root_out=bids_root_anon,
datatypes="meg", # Only MEG data
daysback=10,
)
print_dir_tree(bids_root_anon / "sub-emptyroom") # Easy to see effects here
Anonymizing BIDS dataset
Input: /home/circleci/mne_data/MNE-sample-data-bids
Output: /home/circleci/mne_data/MNE-sample-data-bids-anon
Shifting recording dates by 10 days (0.0 years).
Using the following subject ID anonymization mapping:
sub-ABC123 → sub-1
sub-emptyroom → sub-emptyroom
0%| | Anonymizing : 0/4 [00:00<?, ?it/s]
25%|██▌ | Anonymizing : 1/4 [00:00<00:01, 2.94it/s]
75%|███████▌ | Anonymizing : 3/4 [00:01<00:00, 2.70it/s]
100%|██████████| Anonymizing : 4/4 [00:01<00:00, 3.58it/s]
|sub-emptyroom/
|--- ses-20021126/
|------ sub-emptyroom_ses-20021126_scans.tsv
|------ meg/
|--------- sub-emptyroom_ses-20021126_task-noise_channels.tsv
|--------- sub-emptyroom_ses-20021126_task-noise_meg.fif
|--------- sub-emptyroom_ses-20021126_task-noise_meg.json
Specifying subject IDs#
Anonymized subject IDs are automatically generated as unique numbers in
ascending order. You can control this behavior via the subject_mapping
parameter. Set it to None
to avoid changing the subject IDs, e.g., in
case they’re already anonymized. You can pass a dictionary that maps original
subject IDs to the anonymize IDs. Lastly, you can also pass a function that
accepts a list of original IDs and returns such a dictionary.
shutil.rmtree(bids_root_anon)
subject_mapping = {"ABC123": "anonymous", "emptyroom": "emptyroom"}
anonymize_dataset(
bids_root_in=bids_root,
bids_root_out=bids_root_anon,
datatypes="meg",
subject_mapping=subject_mapping,
)
print_dir_tree(bids_root_anon)
Anonymizing BIDS dataset
Determining "daysback" for anonymization.
Input: /home/circleci/mne_data/MNE-sample-data-bids
Output: /home/circleci/mne_data/MNE-sample-data-bids-anon
Shifting recording dates by 35383 days (96.9 years).
Using the following subject ID anonymization mapping:
sub-ABC123 → sub-anonymous
sub-emptyroom → sub-emptyroom
0%| | Anonymizing : 0/4 [00:00<?, ?it/s]
25%|██▌ | Anonymizing : 1/4 [00:00<00:01, 2.98it/s]
75%|███████▌ | Anonymizing : 3/4 [00:01<00:00, 2.70it/s]
100%|██████████| Anonymizing : 4/4 [00:01<00:00, 3.59it/s]
|MNE-sample-data-bids-anon/
|--- README
|--- dataset_description.json
|--- participants.json
|--- participants.tsv
|--- sub-anonymous/
|------ sub-anonymous_scans.tsv
|------ meg/
|--------- sub-anonymous_acq-calibration_meg.dat
|--------- sub-anonymous_acq-crosstalk_meg.fif
|--------- sub-anonymous_coordsystem.json
|--------- sub-anonymous_task-audiovisual_channels.tsv
|--------- sub-anonymous_task-audiovisual_events.json
|--------- sub-anonymous_task-audiovisual_events.tsv
|--------- sub-anonymous_task-audiovisual_meg.fif
|--------- sub-anonymous_task-audiovisual_meg.json
|--- sub-emptyroom/
|------ ses-19060121/
|--------- sub-emptyroom_ses-19060121_scans.tsv
|--------- meg/
|------------ sub-emptyroom_ses-19060121_task-noise_channels.tsv
|------------ sub-emptyroom_ses-19060121_task-noise_meg.fif
|------------ sub-emptyroom_ses-19060121_task-noise_meg.json
Reproducibility#
Every time you run this function, the automatically-generated subject IDs and the timeshift may differ (unless you excplicitly specify them as described above), as they are determined randomly.
To ensure results are reproducible across runs, you can pass the
random_state
parameter, causing the random number generator to produce
the same results every time you execute the function. This may come in handy
e.g. in situations where you discover a problem with the data while working
with the anonymized dataset, fix the issue in the original dataset, and
run anonymization again.
(Note that throughout this example, we only had a single subject in our
dataset, meaning it will always be assigned the anonymized ID 1
. Only
in a dataset with multiple subjects will the effects of randomly-picked IDs
become apparent.)
Note
Passing random_state
merely guarantees that subject IDs and time shift
remain the same across anonymization runs if the original dataset
remained unchanged. It does not allow you to incrementally add data
(e.g., a new participant) to an anonymized dataset: If the original
dataset changes and you want the changes anonymized, you will need to
anonymize the entire dataset again.
for i in range(2):
print(f"\n\nRun {i + 1}\n")
shutil.rmtree(bids_root_anon)
anonymize_dataset(
bids_root_in=bids_root,
bids_root_out=bids_root_anon,
datatypes="meg",
random_state=42,
)
print_dir_tree(bids_root_anon)
Run 1
Anonymizing BIDS dataset
Determining "daysback" for anonymization.
Input: /home/circleci/mne_data/MNE-sample-data-bids
Output: /home/circleci/mne_data/MNE-sample-data-bids-anon
Shifting recording dates by 29215 days (80.0 years).
Using the following subject ID anonymization mapping:
sub-ABC123 → sub-1
sub-emptyroom → sub-emptyroom
0%| | Anonymizing : 0/4 [00:00<?, ?it/s]
25%|██▌ | Anonymizing : 1/4 [00:00<00:00, 3.01it/s]
75%|███████▌ | Anonymizing : 3/4 [00:01<00:00, 2.72it/s]
100%|██████████| Anonymizing : 4/4 [00:01<00:00, 3.61it/s]
|MNE-sample-data-bids-anon/
|--- README
|--- dataset_description.json
|--- participants.json
|--- participants.tsv
|--- sub-1/
|------ sub-1_scans.tsv
|------ meg/
|--------- sub-1_acq-calibration_meg.dat
|--------- sub-1_acq-crosstalk_meg.fif
|--------- sub-1_coordsystem.json
|--------- sub-1_task-audiovisual_channels.tsv
|--------- sub-1_task-audiovisual_events.json
|--------- sub-1_task-audiovisual_events.tsv
|--------- sub-1_task-audiovisual_meg.fif
|--------- sub-1_task-audiovisual_meg.json
|--- sub-emptyroom/
|------ ses-19221211/
|--------- sub-emptyroom_ses-19221211_scans.tsv
|--------- meg/
|------------ sub-emptyroom_ses-19221211_task-noise_channels.tsv
|------------ sub-emptyroom_ses-19221211_task-noise_meg.fif
|------------ sub-emptyroom_ses-19221211_task-noise_meg.json
Run 2
Anonymizing BIDS dataset
Determining "daysback" for anonymization.
Input: /home/circleci/mne_data/MNE-sample-data-bids
Output: /home/circleci/mne_data/MNE-sample-data-bids-anon
Shifting recording dates by 29215 days (80.0 years).
Using the following subject ID anonymization mapping:
sub-ABC123 → sub-1
sub-emptyroom → sub-emptyroom
0%| | Anonymizing : 0/4 [00:00<?, ?it/s]
25%|██▌ | Anonymizing : 1/4 [00:00<00:01, 2.98it/s]
75%|███████▌ | Anonymizing : 3/4 [00:01<00:00, 2.71it/s]
100%|██████████| Anonymizing : 4/4 [00:01<00:00, 3.59it/s]
|MNE-sample-data-bids-anon/
|--- README
|--- dataset_description.json
|--- participants.json
|--- participants.tsv
|--- sub-1/
|------ sub-1_scans.tsv
|------ meg/
|--------- sub-1_acq-calibration_meg.dat
|--------- sub-1_acq-crosstalk_meg.fif
|--------- sub-1_coordsystem.json
|--------- sub-1_task-audiovisual_channels.tsv
|--------- sub-1_task-audiovisual_events.json
|--------- sub-1_task-audiovisual_events.tsv
|--------- sub-1_task-audiovisual_meg.fif
|--------- sub-1_task-audiovisual_meg.json
|--- sub-emptyroom/
|------ ses-19221211/
|--------- sub-emptyroom_ses-19221211_scans.tsv
|--------- meg/
|------------ sub-emptyroom_ses-19221211_task-noise_channels.tsv
|------------ sub-emptyroom_ses-19221211_task-noise_meg.fif
|------------ sub-emptyroom_ses-19221211_task-noise_meg.json
Total running time of the script: (0 minutes 12.007 seconds)