snakedwi

BIDS app and Snakemake workflow for diffusion-weighted imaging (DWI) pre-processing.

Overview

snakedwi is a comprehensive workflow for preprocessing diffusion MRI data following the BIDS (Brain Imaging Data Structure) standard. The workflow includes:

• Denoising - Optional MP-PCA denoising

• Susceptibility distortion correction (SDC) - Multiple methods including TOPUP, SynthSR, SDCFlows, and SynB0

• Eddy current correction - FSL’s eddy with optional GPU acceleration and slice-to-volume correction

• Brain masking - Multiple methods including BET, SyN registration, and SynthStrip

• Gradient non-linearity correction - Optional scanner-specific correction

• Registration to T1w - Rigid and deformable registration options

• Quality control - Automatic QC reports with eddy_quad

Installation

Prerequisites

• pixi - A fast package manager

Install with pixi

1. Clone the repository:

git clone https://github.com/khanlab/snakedwi.git
cd snakedwi

2. Install dependencies with pixi:

pixi install

This will install snakedwi and all its dependencies in an isolated environment.

Usage

Basic Usage

Run the workflow with Apptainer (recommended for using containerized tools):

pixi run snakedwi /path/to/bids/dir /path/to/output/dir participant --use-apptainer

Dry Run

To see what the workflow will do without running it:

pixi run snakedwi /path/to/bids/dir /path/to/output/dir participant --use-apptainer -np

Running with Multiple Cores

To use all available cores:

pixi run snakedwi /path/to/bids/dir /path/to/output/dir participant --use-apptainer --cores all

Common Options

• --use-apptainer: Use Apptainer/Singularity containers for tool dependencies

• --participant_label: Process specific subject(s), e.g., --participant_label 001 002

• --sdc_method: Choose susceptibility distortion correction method (optimal, topup, synthsr, sdcflow, synb0, none)

• --masking_method: Brain masking method (b0_BET, b0_SyN, b0_synthstrip)

• --cores: Number of cores to use (e.g., --cores 8 or --cores all)

• -np: Dry-run mode (show what will be executed without running)

Example with Options

pixi run snakedwi /path/to/bids/dir /path/to/output/dir participant \
  --use-apptainer \
  --participant_label 001 \
  --sdc_method topup \
  --masking_method b0_synthstrip \
  --cores 8

Input Data Requirements

Your input data must be organized according to the BIDS specification, specifically:

• DWI data in sub-*/dwi/ with .nii.gz images and corresponding .json sidecar files

• Optional T1w anatomical images in sub-*/anat/

• Metadata including PhaseEncodingDirection in JSON files

Output

Processed DWI data will be saved in the specified output directory following the BIDS derivatives format, including:

• Preprocessed DWI images

• Brain masks

• QC reports

• Transformation matrices

• Processing metadata

Documentation

For detailed documentation, visit: https://snakedwi.readthedocs.io

Development

Running Tests

To run the test suite:

pixi run test_all

Code Formatting

To format code:

pixi run quality_fix

To check code quality:

pixi run quality_check

Citation

If you use snakedwi in your research, please cite:

Khan, A. R. (2024). snakedwi: BIDS app and Snakemake workflow for DWI pre-processing.
https://github.com/khanlab/snakedwi

License

This project is licensed under the MIT License - see the LICENSE file for details.

Support

• Issues: Report bugs or request features at GitHub Issues

• Documentation: https://snakedwi.readthedocs.io

• Repository: https://github.com/khanlab/snakedwi

Acknowledgments

snakedwi is developed and maintained by the Khan Lab at Western University.