DiSCo Challenge @MICCAI 2021
Diffusion-Simulated Connectivity Challenge (DiSCo), COMPUTATIONAL DIFFUSION MRI MICCAI 2021
Can your DW-MRI pipeline predict the connectivity of the DiSCo numerical phantoms?
The methodological development in the mapping of the brain structural connectome from diffusion-weighted magnetic resonance imaging (DW-MRI) has raised many hopes in the neuroscientific community. Indeed, the knowledge of the connections between different brain regions is fundamental for studying brain anatomy and its function. The reliability of the structural connectome is therefore of paramount importance. The main goal of this challenge is to evaluate the performance of quantitative connectivity pipelines:
- DW-MRI pre-processing methods,
- Algorithms for fibre orientation distributions estimation,
- Tractography algorithms,
- Tractography filtering methods,
- Algorithms for the calculation of connectivity strength.
For this scope, we have designed three datasets of simulated diffusion-weighted images from three numerical phantoms and an evaluation framework for quantitative tractography. The phantoms are composed of a large collection of synthetic tubular fibres with diameters ranging from 1.4 μm to 4.2 μm (approximately 12,000 fibres), connecting distant Regions of Interest (ROIs). The simulation substrates have a micrometric resolution and an unprecedented size of 1 cubic millimetre to mimic an image acquisition matrix of 40x40x40 voxels. Within each voxel, the signal is simulated using Monte-Carlo simulations of spins dynamics using Monte Carlo sampling with a density of one particle per micrometre cube. This is the first time this technique was used to create phantoms of such size and complexity. After the Monte Carlo simulation of the DW-MRI signal, the resulting image header was set to a voxel size of 1.0 mm isotropic (from 25 μm isotropic), for a final image size of 4x4x4 cm3, compatible with standard pipelines. The simulated images capture microscopic properties of the white matter (e.g. fibre diameter, water diffusing within and around fibres, free water compartment), while also having desirable macroscopic properties resembling the anatomy, such as the smoothness of the fibre trajectories. Each phantom has sixteen ROIs, forming 120 possible connections (distinct pairs of ROIs).