patched-Diffusion-Models-UAD

Codebase for the paper Patched Diffusion Models for Unsupervised Anomaly Detection accepted at MIDL23.

Graphical abstract

Data

We use the IXI data set, the BraTS21 data set and the MSLUB data set for our experiments. You can download/request the data sets here:

• IXI: https://brain-development.org/ixi-dataset/
• BraTS21: http://braintumorsegmentation.org/
• MSLUB: https://lit.fe.uni-lj.si/en/research/resources/3D-MR-MS/

Data Preprocessing

Warning: The Preprocessing is bugged right now and does not represent the steps taken in the paper. A fix will be pushed asap.

Before processing, you need to extract the downloaded zip files and organize them as follows:

├── IXI
│   ├── t2 
│   │   ├── IXI1.nii.gz
│   │   ├── IXI2.nii.gz
│   │   └── ... 
│   └── ...
├── MSLUB
│   ├── t2 
│   │   ├── MSLUB1.nii.gz
│   │   ├── MSLUB2.nii.gz
│   │   └── ...
│   ├── seg
│   │   ├── MSLUB1_seg.nii.gz
│   │   ├── MSLUB2_seg.nii.gz
│   │   └── ...
│   └── ...
├── Brats21
│   ├── t2 
│   │   ├── Brats1.nii.gz
│   │   ├── Brats2.nii.gz
│   │   └── ...
│   ├── seg
│   │   ├── Brats1_seg.nii.gz
│   │   ├── Brats2_seg.nii.gz
│   │   └── ...
│   └── ...
└── ...

We apply several preprocessing steps to the data, including resampling to 1.0 mm, skull-stripping with HD-BET, registration to the SRI Atlas, cutting black boarders and N4 Bias correction. To run the preprocessing, you need to clone and setup the HD-BET tool for skull-stripping. For each data set there is an individual bash script that performs the preprocessing in the preprocessing directory. To preprocess the data, go to the preprocessing directory:

cd preprocessing

execute the bash script:

bash prepare_IXI.sh <input_dir> <output_dir>

the <input_dir> refers to the directory where the downloaded, raw data is stored.

Note, that you need to provide absolute paths and this script will use a GPU for skull-stripping.

Example for the IXI data set:

bash prepare_IXI.sh /raw_data/IXI/ $(pwd)

This will create 4 different folders with the results of the intermediate preprocessing steps. The final scans are located in /processed_data/v4correctedN4_non_iso_cut

After preprocessing, place the data (the folder v4correctedN4_non_iso_cut) in your DATA_DIR.

cp -r <output_dir>/IXI <DATA_DIR>/Train/ixi
cp -r <output_dir>/MSLUB <DATA_DIR>/Test/MSLUB
cp -r <output_dir>/Brats21 <DATA_DIR>/Test/Brats21

The directory structure of <DATA_DIR> should look like this:

<DATA_DIR>
├── Train
│   ├── ixi
│   │   ├── mask
│   │   ├── t2
├── Test
│   ├── Brats21
│   │   ├── mask
│   │   ├── t2
│   │   ├── seg
│   ├── MSLUB
│   │   ├── mask
│   │   ├── t2
│   │   ├── seg
├── splits
│   ├──  Brats21_test.csv        
│   ├──  Brats21_val.csv   
│   ├──  MSLUB_val.csv 
│   ├──  MSLUB_test.csv
│   ├──  IXI_train_fold0.csv
│   ├──  IXI_train_fold1.csv 
│   └── ...                
└── ...

You should then specify the location of <DATA_DIR> in the pc_environment.env file. Additionally, specify the <LOG_DIR>, where runs will be saved.

Environment Set-up

To download the code type

git clone git@github.com:FinnBehrendt/patched-Diffusion-Models-UAD.git

In your linux terminal and switch directories via

cd patched-Diffusion-Models-UAD

To setup the environment with all required packages and libraries, you need to install anaconda first.

Then, run

conda env create -f environment.yml -n pddpm-uad

and subsequently run

conda activate pddpm-uad
pip install -r requirements.txt

to install all required packages.

Run Experiments

To run the training and evaluation of the pDDPM, simply execute

python run.py experiment=MIDL23_DDPM/DDPM_patched

in your terminal.

Citation

If you make use of our work, we would be happy if you cite it via

    @article{behrendt2023patched,
      title={Patched diffusion models for unsupervised anomaly detection in brain mri},
      author={Behrendt, Finn and Bhattacharya, Debayan and Kr{\"u}ger, Julia and Opfer, Roland and Schlaefer, Alexander},
      journal={arXiv preprint arXiv:2303.03758},
      year={2023}
      }