skip to main content
Language:
Search Limited to: Search Limited to: Resource type Show Results with: Show Results with: Search type Index

Mapping magnetic susceptibility anisotropies of white matter in vivo in the human brain at 7ANBT

NeuroImage (Orlando, Fla.), 2012-08, Vol.62 (1), p.314-330 [Peer Reviewed Journal]

ISSN: 1053-8119 ;EISSN: 1095-9572 ;DOI: 10.1016/j.neuroimage.2012.04.042

Full text available

Citations Cited by
  • Title:
    Mapping magnetic susceptibility anisotropies of white matter in vivo in the human brain at 7ANBT
  • Author: Li, Xu ; Vikram, Deepti S ; Lim, Issel Anne L ; Jones, Craig K ; Farrell, Jonathan AD ; van Zijl, Peter CM
  • Subjects: Anisotropy
  • Is Part Of: NeuroImage (Orlando, Fla.), 2012-08, Vol.62 (1), p.314-330
  • Description: High-resolution magnetic resonance phase- or frequency-shift images acquired at high field show contrast related to magnetic susceptibility differences between tissues. Such contrast varies with the orientation of the organ in the field, but the development of quantitative susceptibility mapping (QSM) has made it possible to reproducibly image the intrinsic tissue susceptibility contrast. However, recent studies indicate that magnetic susceptibility is anisotropic in brain white matter and, as such, needs to be described by a symmetric second-rank tensor ( I A= A= ). To fully determine the elements of this tensor, it would be necessary to acquire frequency data at six or more orientations. Assuming cylindrical symmetry of the susceptibility tensor in myelinated white matter fibers, we propose a simplified method to reconstruct the susceptibility tensor in terms of a mean magnetic susceptibility, M M S = ( I // + 2 I aY ) / 3 and a magnetic susceptibility anisotropy, M S A = I / / a I aY , where I// and IaY are susceptibility parallel and perpendicular to the white matter fiber direction, respectively. Computer simulations show that with a practical head rotation angle of around 20 degree -30 degree , four head orientations suffice to reproducibly reconstruct the tensor with good accuracy. We tested this approach on whole brain 1 X 1 X 1 mm3 frequency data acquired from five healthy subjects at 7 T. The frequency information from phase images collected at four head orientations was combined with the fiber direction information extracted from diffusion tensor imaging (DTI) to map the white matter susceptibility tensor. The MMS and MSA were quantified for regions in several large white matter fiber structures, including the corona radiata, posterior thalamic radiation and corpus callosum. MMS ranged from a 0.037 to a 0.053 ppm (referenced to CSF being about zero). MSA values could be quantified without the need for a reference and ranged between 0.004 and 0.029 ppm, in line with the expectation that the susceptibility perpendicular to the fiber is more diamagnetic than the one parallel to it.
  • Language: English
  • Identifier: ISSN: 1053-8119
    EISSN: 1095-9572
    DOI: 10.1016/j.neuroimage.2012.04.042
  • Source: ProQuest One Psychology
    Alma/SFX Local Collection
    ProQuest Central
Back to results list
INSPIRE LIBRARY - TON DUC THANG UNIVERSITY (84-028) 37 755 057 Feedback
19 Nguyen Huu Tho St. Dist.7, HCM thuvien@tdtu.edu.vn

Copyright © 2017 INSPIRE LIBRARY - TON DUC THANG UNIVERSITY

Searching Remote Databases, Please Wait