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This model was pretrained on brain MRI from consortia that impose Data Use Agreements (including ADNI and PPMI). By requesting access you confirm that you will use these weights for non-commercial research only, will not attempt to reconstruct or re-identify any individual scan or subject, and will comply with the terms of the source datasets. No patent rights are granted; see the License and intellectual property section.

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arXiv

BrainG3N: 3D Masked Autoencoder for Brain MRI (ViT-L)

Weights for BrainG3N: A Dual-Purpose Tokenizer for Controllable 3D Brain MRI Generation (arXiv:2606.19651).

Self-supervised ViT-Large encoder for 3D brain MRI. Pretrained with masked autoencoding on ~33k volumes spanning 18 public cohorts, covering healthy controls, neurodegenerative disease, neurodevelopmental cohorts, and glioma. The frozen encoder produces general-purpose features for clinical probing without fine-tuning.

Model

Architecture ViT-Large masked autoencoder (12 layers, d=1152, 16 heads)
Patch size 16x16x16 voxels
Input 160x192x160 voxels, single channel
Tokens 1,200 (CLS prepended during encoding, stripped from output)
Masking ratio 0.7

Quick start

git clone https://huggingface.co/gevaertlab/braing3n
cd braing3n && pip install -r requirements.txt
from modeling import BrainMAEEncoder
from preprocessing import load_volume

encoder = BrainMAEEncoder.from_pretrained("gevaertlab/braing3n", device="cuda")

x = load_volume("sub-0001_t1_preprocessed.nii.gz")   # [1, 1, 160, 192, 160]
tokens = encoder.encode(x.cuda())                    # [1, 1200, 1152]
features = tokens.mean(dim=1)                        # [1, 1152]

features is the representation used for the results reported in the paper.

Ready-made scripts

Script Does Needs
extract_features.py Directory of NIfTIs to features.pt + features.csv (one 1152-d row per volume) encoder
reconstruct.py Encode then decode one volume; writes original + reconstruction encoder + decoder
generate.py Sample synthetic volumes from the conditional DiT DiT + decoder
# Batch feature extraction -- the common case
python extract_features.py --input_dir /path/to/scans --output_dir features/

# Non-BIDS filenames
python extract_features.py --input_dir scans/ --output_dir features/ \
    --pattern '*_t1c_preprocessed.nii.gz' --id_regex 'CGGA_([A-Za-z0-9]+)_'

# Round-trip one volume through the d'=32 bottleneck
python reconstruct.py --input scan.nii.gz --output recon/

# Conditional generation (--list_conditions shows what this checkpoint accepts)
python generate.py --num_samples 4 --disease GBM --modality t1c --output samples/

Input requirements (read this)

The encoder expects volumes that are already skull-stripped and affinely registered to a common template. It applies only two on-the-fly steps: pad/crop to 160x192x160 and a nonzero-masked z-score. Feeding raw scanner output produces meaningless features -- this is the most common failure mode.

Data is z-scored, not scaled to [0, 1].

Companion weights

Subfolder Component Use
(root) MAE ViT-L encoder Feature extraction
decoder_d32/ Projection (1152->32) + CNN decoder Reconstruct volumes from latents
dit_d32_6cond/ Conditional DiT (flow matching) Conditional generation in latent space

Results

Evaluation and benchmark numbers are reported in the paper (arXiv:2606.19651). This repository hosts the weights only.

Training data

upenn, ucsf, abide, abide2, adhd200, adni, bgsp, corr, fcon1000, hbn, hcp_ya, ixi, nki, nki2, oasis1, oasis2, ppmi, schizo

Cohorts were used under their respective data use agreements. No individual scans are redistributed here -- only model weights.

License and intellectual property

Weights and accompanying code are released under CC BY-NC 4.0 for non-commercial research use only.

This is a copyright license. It grants no license, express or implied, to any patent or patent application covering the methods described in the paper or implemented here. All patent rights are reserved. Commercial use, or any use beyond non-commercial research, requires a separate agreement -- contact the authors and the Stanford Office of Technology Licensing.

Limitations

  • Structural MRI only (T1, T1c, T2, FLAIR). Not validated on DWI, SWI, fMRI, or CT.
  • Site is near-perfectly decodable from the features (multi-way site AUC ~1.0), so scanner and acquisition signal is present in the representation. Use site-aware cross-validation for any downstream clinical claim.
  • Not a medical device. Research use only.

Citation

@article{vanpuyvelde2026braing3n,
  title={{BrainG3N}: A Dual-Purpose Tokenizer for Controllable 3D Brain {MRI} Generation},
  author={Van Puyvelde, Max and Gulluk, Ibrahim and Van Criekinge, Wim and Gevaert, Olivier},
  journal={arXiv preprint arXiv:2606.19651},
  year={2026}
}
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