An open access recursive magnetization evolution algorithm framework is proposed for simulating arbitrary pulse sequences in presence of time-variant gradients with arbitrary orientations in three dimensions. It overcomes the sequence symmetry requirements of the extended phase graph algorithm for solving the Bloch-Torrey equation efficiently, and could present the signal modulation in the 3D spatial domain.
- Xiang Gao
- V. G. Kiselev
- Maxim Zaitsev
-Input file: demo_seq_dt.txt
-Simulation command: 3D_SR-PG_tensor.exe demo_seq_dt.txt
-Output file: output1.txt and output1_Nspins.txt
To interpret the output file, one could use util/KmapSignal2.m function, which returns:
-logData.kvector,[kx,ky,kz]
-logData.signal,[signal real part,signal imaginary part,0]
To further transform the signal into spatial domain, one can use function util/IMG_DFT.m with additional input parameters, eg:
-global FOV; FOV=192;
-global Mat; Mat=64;
It returns:
-slogData.sig3d, 2D Image(Mag) of x-y, y-z, x-z plane for each echo. Image can be pre-filtered by setting kfilter in Kspace
-slogData.pha3d, 2D Image(Phas) of x-y, y-z, x-z plane for each echo. Image can be pre-filtered by setting kfilter in Kspace
-example_offres_MRF.m, Fast off-resonance calculation for Pseudo-SSFP dictionary building in magnetic resonance fingerprinting
-example_PRESS_MRSI.m, 3D signal evolution visualization for the PRESS-based magnetic spectroscopic imaging
The Details of those two examples are reported in the corresponding paper:
Three-dimensional spatially resolved phase graph framework
One more example:
Strategies to improve intratrain prospective motion correction for turbo spin-echo sequences with constant flip angles
Anisotropic diffusion simulation is supported