dHCP Fourth Data Release (May 2024)

Data directory structure

The structure of data directory and convention of files naming will follow the BIDS specification (v1.5.0-dev).

Participants and sessions

The participants.tsv for each BIDS pipeline has a number of extra columns beyond participant_id. These have the following meaning:

The sessions.tsv file has extra columns beyond session_id. These have the following meaning:

The MRI scans were reviewed by a specialist perinatal neuroradiologist who scored each subject using the following scale:

1. Normal appearance for age

2. Incidental findings with unlikely significance for clinical outcome or analysis (e.g. subdural haemorrhage. Isolated subependymal cysts. Mild inferior vermis rotation)

3. Incidental findings with unlikely clinical significance but possible analysis significance (e.g. several punctate lesions or other focal white matter / cortical lesions not thought to be of clinical significance)

4. Incidental findings with possible clinical significance. Unlikely analysis significance (e.g. Isolated non brain anomaly for example in pituitary / on tongue)

5. Incidental finding with possible / likely significance for both clinical and imaging analysis (e.g. Major lesions within white matter cortex, cerebellum and or basal ganglia; small head / brain < 1st centile)

6. Q, meaning poor quality anatomical data

Image Spaces

Images are released in their own native image space with no correspondence to other images (within or across subjects). Transforms (affine and warps) are provided to align images within subjects and to a common space.

Transform filenames contain a from key and a to key to indicate the direction of the transform. The from value is the space-label for the origin/source/moving image, and the to value is the space-label for the reference/target image.

Volumetric transforms have the key-value mode-image, whereas surface transforms have the key-value mode-sphere.

Non-linear volumetric transforms are FSL format with the extension .nii.gz, rigid/affine volumetric transforms have the extension .mat, and surface transforms have the extension .surf.gii.

Examples:

# volumetric affine transform
xfm/sub-{subid}_ses-{sesid}_from-{space-label}_to-{space-label}_mode-image.mat

# volumetric nonlinear transform
xfm/sub-{subid}_ses-{sesid}_from-{space-label}_to-{space-label}_mode-image.nii.gz 

# surface transform
xfm/sub-{subid}_ses-{sesid}_hemi-{hemi}_from-{space-label}_to-{space-label}_dens-32k_mode-sphere.surf.gii 

Space labels:

Reconstruction Pipeline

Path: rawdata/sub-{subid}/ses-{sesid}

Path: sourcedata/sub-{subid}/ses-{sesid}

Structural pipeline

Path: derivatives/dhcp_anat_pipeline/sub-{subid}/ses-{sesid}

Diffusion EDDY pipeline

Path: derivatives/dhcp_dmri_eddy_pipeline/sub-{subid}/ses-{sesid}

Diffusion SHARD pipeline

Path: derivatives/dhcp_dmri_shard_pipeline/sub-{subid}/ses-{sesid}

Functional pipeline

Path: derivatives/dhcp_fmri_pipeline/sub-{subid}/ses-{sesid}