Expand description
FANSI nonlinear TV / TGV dipole inversion.
Nonlinear total-variation (nlTV) and nonlinear total-generalized-variation (nlTGV) QSM dipole inversion with a nonlinear (wrapped-phase) data-fidelity term, solved with ADMM plus an inner complex-argument Newton iteration.
The nonlinear fidelity models the field data as exp(i * D x) and matches
it to the wrapped local-field phase, which makes the reconstruction robust to
phase-wrap / high-field regimes.
References:
- nlTV: Milovic, C., Bilgic, B., Zhao, B., et al. (2018). “Fast nonlinear susceptibility inversion with variational regularization.” Magnetic Resonance in Medicine, 80(2):814-821. https://doi.org/10.1002/mrm.27073
- nlTGV: the total-generalized-variation variant of the above.
Ported faithfully from the FANSI toolbox nlTV.m and nlTGV.m
(https://gitlab.com/cmilovic/FANSI-toolbox).
§Units / phase_scale
The FANSI fidelity is a phase (radians) model: sin(z2 - phase). If the
input local_field is already radians, use phase_scale = 1.0. If it is
ppm-scale, phase_scale should convert ppm -> radians (2*pi*gamma*B0*TE);
the returned map is divided by phase_scale so it is expressed on the same
scale as the input field.
Structs§
- Fansi
Params - FANSI nlTV/nlTGV parameters.
Functions§
- fansi
- FANSI nlTV/nlTGV dipole inversion.
- nltgv 🔒
- Nonlinear total-generalized-variation dipole inversion (FANSI
nlTGV.m). - nltv 🔒
- Nonlinear total-variation dipole inversion (FANSI
nlTV.m). - norm2 🔒
- L2 norm of a real slice.
- spectral_
mul_ 🔒assign - Multiply a complex spectral array in place by a complex multiplier array.