This MATLAB code simulates dMRI sequences with echo planar imaging (EPI) and spiral trajectories and characterizes the resulting point spread function (PSF).
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The spiral trajectories are generated using Brian Hargreaves’ code, which can be found here: mrsrl.stanford.edu/~brian/vdspiral/
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The 2D PSF analysis and image reconstruction requires a GPU.
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The images are reconstructed using the expanded signal model, which can be found here: github.com/TardifLab/ESM_image_reconstruction
The effective resolution of single-shot readout trajectories is measured using the Full Width at Half Maximum (FWHM) in phase-encode direction (PE). Follow steps in example_FWHM.m to learn how to use the code for FWHM calculation.
The accuracy of spatial encoding is further characterized by measuring the specificity and sharpening factor of the 2D PSF. Follow example_PSF_2D.m for the definitions of specificity and sharpening factor.
A digital brain phantom and coil sensitivity maps are available to simulate the image reconstruction pipeline and evaluate its impact on image quality. See example_phantom_sim.m for an example on how to use the code.
Implementation of the multiple replica method (Robson et al., 2008) to measure SNR of MRI scans using raw k-space data and noise measurements. example_multiple_replice_recon.m includes the steps to reconstruct the multiple replicas.
Link to the dataset: https://doi.org/10.5683/SP3/V7ITEH
For any question about the code please contact: [email protected]