Magnetic susceptibility contrast in MRI

What is magnetic susceptibility

  • ferromagnetic/diamagnetic/paramagnetic tissue
  • isotropic/anisotropic susceptibility

Pulse sequences

  • Radio-frequency excitation pulse followed by a signal readout block (could be GRE, EPI or spiral readout)
  • gradient-recalled-echo sequences with a single (GRE) or multiple (mGRE) echoes

Signal pre-processing

  • Phase unwrapping methods: Homodyne filter, Laplacian phase unwrap, HARPERELLA (more tba); Review: Robinson et al., 2017
  • Coil combination techniques: Roemer approach, virtual coil, ASPIRE, COMPOSER (more tba); Review: Robinson et al., 2017
  • Background field removal methods: Homodyne filter, SHARP, vSHARP, HAPPARELLA, FDM, PDF (more tba); Review: Schweser et al., 2017

Unlike the majority of in vivo MR techtiques which process the magnitude data, susceptibility contrast is mainly using phase data of the signal. Phase data reflects local (=sub-voxel) and non-local magnetic field variations (e.g. RF-related phase offsets or large-length-scale magnetic field inhomogeneities). Local field changes are caused by susceptibility variations within the object, while the non-local field changes originate from sources from outside of the object. Therefore the first challenge is to remove the background field effects.

End products

End products:


Tool Short description Programming Language Source code accessibility
STI Suite Phase data pre-processing tools, SWI&QSM calculation Matlab Open source


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Page last modified on Friday May 10, 2019 21:47:51 GMT-0000 by jeans_walker.