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Mean magnetic susceptibility regularized susceptibility tensor imaging ( MMSR ‐ STI ) for estimating orientations of white matter fibers in human brain
Author(s) -
Li Xu,
Zijl Peter C. M.
Publication year - 2014
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.25322
Subject(s) - diffusion mri , white matter , tensor (intrinsic definition) , anisotropy , fractional anisotropy , magnetic susceptibility , nuclear magnetic resonance , orientation (vector space) , inverse problem , physics , magnetic resonance imaging , mathematical analysis , mathematics , medicine , optics , condensed matter physics , geometry , radiology
Purpose An increasing number of studies show that magnetic susceptibility in white matter fibers is anisotropic and may be described by a tensor. However, the limited head rotation possible for in vivo human studies leads to an ill‐conditioned inverse problem in susceptibility tensor imaging (STI). Here we suggest the combined use of limiting the susceptibility anisotropy to white matter and imposing morphology constraints on the mean magnetic susceptibility (MMS) for regularizing the STI inverse problem. Methods The proposed MMS regularized STI (MMSR‐STI) method was tested using computer simulations and in vivo human data collected at 3T. The fiber orientation estimated from both the STI and MMSR‐STI methods was compared to that from diffusion tensor imaging (DTI). Results Computer simulations show that the MMSR‐STI method provides a more accurate estimation of the susceptibility tensor than the conventional STI approach. Similarly, in vivo data show that use of the MMSR‐STI method leads to a smaller difference between the fiber orientation estimated from STI and DTI for most selected white matter fibers. Conclusion The proposed regularization strategy for STI can improve estimation of the susceptibility tensor in white matter. Magn Reson Med 72:610–619, 2014. © 2014 Wiley Periodicals, Inc.