title: Echo time-dependent quantitative susceptibility mapping contains information on tissue properties.
abstract: Magnetic susceptibility is a physical property of matter that varies depending on chemical composition and abundance of different molecular species. Interest is growing in mapping of magnetic susceptibility in the human brain using magnetic resonance imaging techniques, but the influences affecting the mapped values are not fully understood.
  
  
  
  We performed quantitative susceptibility mapping on 7 Tesla (T) multiple echo time gradient recalled echo data and evaluated the trend in 10 regions of the human brain. Temporal plots of susceptibility were performed in the caudate, pallidum, putamen, thalamus, insula, red nucleus, substantia nigra, internal capsule, corpus callosum, and fornix. We implemented an existing three compartment signal model and used optimization to fit the experimental result to assess the influences that could be responsible for our findings.
  
  
  
  The temporal trend in susceptibility is different for different brain regions, and subsegmentation of specific regions suggests that differences are likely to be attributable to variations in tissue structure and composition. Using a signal model, we verified that a nonlinear temporal behavior in experimentally computed susceptibility within imaging voxels may be the result of the heterogeneous composition of tissue properties.
  
  
  
  Decomposition of voxel constituents into meaningful parameters may lead to informative measures that reflect changes in tissue microstructure. Magn Reson Med 77:1946-1958, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Centre for Advanced Imaging, the University of Queensland, Brisbane, Australia.
authors.forename: Surabhi
authors.initials: S
authors.lastname: Sood
authors.affiliation: Centre for Advanced Imaging, the University of Queensland, Brisbane, Australia.
authors.forename: Javier
authors.initials: J
authors.lastname: Urriola
authors.affiliation: Centre for Advanced Imaging, the University of Queensland, Brisbane, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Reutens
authors.affiliation: Siemens Ltd., Brisbane, Australia.
authors.forename: Kieran
authors.initials: K
authors.lastname: O'Brien
authors.affiliation: Centre for Advanced Imaging, the University of Queensland, Brisbane, Australia.
authors.forename: Steffen
authors.initials: S
authors.lastname: Bollmann
authors.affiliation: Centre for Advanced Imaging, the University of Queensland, Brisbane, Australia.
authors.forename: Markus
authors.identifier: 0000-0002-0520-1843
authors.initials: M
authors.lastname: Barth
authors.affiliation: Centre for Advanced Imaging, the University of Queensland, Brisbane, Australia.
authors.forename: Viktor
authors.initials: V
authors.lastname: Vegh
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D001931:Brain Mapping / Q000379:methods; D017352:Echo-Planar Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male
keywords: magnetic resonance imaging; quantitative susceptibility mapping; tissue composition; tissue structure; ultra-high field imaging