JETS for Diffusion MRI at 7 T

Demonstration on Joint k-q-slice rEconsTruction framework for Shift-encoded (JETS) Diffusion MRI at 7 T

Pulse Sequence

Complementary k-q-space sampling

Figure 1. (A) An example diffusion-weighted magnetic resonance imaging (DWI, or DW-MRI) acquisition based on three-shot interleaved echo-planar imaging (iEPI). (B) The proposed shift encoding scheme. Given the use of three-shot iEPI, every three columns have the same color, representing one DWI acquisition. The subsequent DWI acquisition is shifted by one $k_y$ line to create complementary k-q-space sampling pattern.

NAViEPI

Figure 2. Navigator-based iEPI with consistent effective echo spacing between the imaging and the navigator echo - where iEPI meets readout-segmented EPI (rsEPI). This enables (1) minimal distortion mismatch between imaging and navigator echoes, (2) reliable shot-to-shot phase variation estimation, and (3) flexible number of shots.

Joint k-q-Slice Reconstruction

Forward modeling

Figure 3. An illustration of the formation of the forward operator in our joint k-q-slice reconstruction. The indices 'x' and 'y' denote the image size, 'z' denotes the multi-band slices, 'q' denotes the diffusion encoding, 's' denotes the shots, and 'c' denotes the coil sensitivities.

Iterative reconstruction

With the above forward model, the reconstruction jointly and iteratively solves for multi-band and multi-diffusion-direction images.

Download Data

You can either manually download them on Zenodo or execute the following commands in a bash terminal:

cd data
python load.py

Interactive Code Demonstration

• JETS reconstruction:

• LLR regularization:

• Single-Shot Multi-Band EPI SENSE reconstruction:

References

If you find the open-source codes/data useful, please cite:

@Article{tan_2024_diff7t,
    Title     = {{Accelerated Diffusion Weighted Magnetic Resonance Imaging at 7 T: Joint Reconstruction for Shift-Encoded Navigator-based Interleaved Echo Planar Imaging (JETS-NAViEPI)}},
    Author    = {Tan, Zhengguo and Liebig, Patrick A and Heidemann, Robin M and Laun, Frederik B and Knoll, Florian},
    Journal   = {Imaging Neuroscience},
    Year      = {2024},
    Volume    = {2},
    Pages     = {1-15},
    doi       = {10.1162/imag_a_00085}
}