title: Magnetic susceptibility anisotropy outside the central nervous system.
abstract: Magnetic-susceptibility-based MRI has made important contributions to the characterization of tissue microstructure, chemical composition, and organ function. This has motivated a number of studies to explore the link between microstructure and susceptibility in organs and tissues throughout the body, including the kidney, heart, and connective tissue. These organs and tissues have anisotropic magnetic susceptibility properties and cellular organizations that are distinct from the lipid organization of myelin in the brain. For instance, anisotropy is traced to the epithelial lipid orientation in the kidney, the myofilament proteins in the heart, and the collagen fibrils in the knee cartilage. The magnetic susceptibility properties of these and other tissues are quantified using specific MRI tools: susceptibility tensor imaging (STI), quantitative susceptibility mapping (QSM), and individual QSM measurements with respect to tubular and filament directions determined from diffusion tensor imaging. These techniques provide complementary and supplementary information to that produced by traditional MRI methods. In the kidney, STI can track tubules in all layers including the cortex, outer medulla, and inner medulla. In the heart, STI detected myofibers throughout the myocardium. QSM in the knee revealed three unique layers in articular cartilage by exploiting the anisotropic susceptibility features of collagen. While QSM and STI are promising tools to study tissue susceptibility, certain technical challenges must be overcome in order to realize routine clinical use. This paper reviews essential experimental findings of susceptibility anisotropy in the body, the underlying mechanisms, and the associated MRI methodologies. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, USA.
authors.forename: Russell
authors.initials: R
authors.lastname: Dibb
authors.affiliation: Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, USA.|Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah, Salt Lake City, UT, USA.
authors.forename: Luke
authors.initials: L
authors.lastname: Xie
authors.affiliation: Brain Imaging and Analysis Center, Duke University Medical Center, Durham, NC, USA.
authors.forename: Hongjiang
authors.initials: H
authors.lastname: Wei
authors.affiliation: Center for In Vivo Microscopy, Department of Radiology, Duke University Medical Center, Durham, NC, USA.|Brain Imaging and Analysis Center, Duke University Medical Center, Durham, NC, USA.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Liu
mesh_terms: D000818:Animals; D016880:Anisotropy; D019317:Evidence-Based Medicine; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D060526:Magnetic Fields; D008279:Magnetic Resonance Imaging / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014781:Viscera / Q000033:anatomy & histology / Q000000981:diagnostic imaging* / Q000502:physiology*
keywords: anisotropic magnetic susceptibility; quantitative susceptibility mapping; resonance frequency shift; susceptibility tensor imaging