BIfTI breast phantom

Synthetic breast phantom data in BIfTI phantom data standard (https://github.com/mrx-org/bifti-phantoms.git) for MRI simulation using MR-zero. Phantom was presented and used for the simulations in the article "Breast Digital Twin: Towards simulation-guided acceleration of method development". It includes: multi-slice breast phantom for 3 T field strength: breast_3T.json multi-slice breast phantom for 7 T field strength: breast_7T.json single-slice breast phantom for 3 T field strength (with partial volume effects): breast_3T_single_slice_paper.json single-slice breast phantom for 7 T field strength (with partial volume effects): breast_7T_single_slice_paper.json