title: Susceptibility-weighted imaging and quantitative susceptibility mapping in the brain.
abstract: Susceptibility-weighted imaging (SWI) is a magnetic resonance imaging (MRI) technique that enhances image contrast by using the susceptibility differences between tissues. It is created by combining both magnitude and phase in the gradient echo data. SWI is sensitive to both paramagnetic and diamagnetic substances which generate different phase shift in MRI data. SWI images can be displayed as a minimum intensity projection that provides high resolution delineation of the cerebral venous architecture, a feature that is not available in other MRI techniques. As such, SWI has been widely applied to diagnose various venous abnormalities. SWI is especially sensitive to deoxygenated blood and intracranial mineral deposition and, for that reason, has been applied to image various pathologies including intracranial hemorrhage, traumatic brain injury, stroke, neoplasm, and multiple sclerosis. SWI, however, does not provide quantitative measures of magnetic susceptibility. This limitation is currently being addressed with the development of quantitative susceptibility mapping (QSM) and susceptibility tensor imaging (STI). While QSM treats susceptibility as isotropic, STI treats susceptibility as generally anisotropic characterized by a tensor quantity. This article reviews the basic principles of SWI, its clinical and research applications, the mechanisms governing brain susceptibility properties, and its practical implementation, with a focus on brain imaging.
authors.affiliation: Brain Imaging and Analysis Center, School of Medicine, Duke University, Durham, North Carolina, USA.|Department of Radiology, School of Medicine, Duke University, Durham, North Carolina, USA.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Liu
authors.affiliation: Research Imaging Institute, University of Texas Health Science Center at San Antonio, Texas, USA.|Department of Ophthalmology, University of Texas Health Science Center at San Antonio, Texas, USA.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Radiology, School of Medicine, Loma Linda University, Loma Linda, California, USA.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Tong
authors.affiliation: Department of Radiology, Lucile Packard Children's Hospital, Stanford University, Palo Alto, California, USA.
authors.forename: Kristen W
authors.initials: KW
authors.lastname: Yeom
authors.affiliation: Department of Radiology, School of Medicine, Duke University, Durham, North Carolina, USA.
authors.forename: Samuel
authors.initials: S
authors.lastname: Kuzminski
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology*; D001927:Brain Diseases / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D066128:Gray Matter / Q000473:pathology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D066127:White Matter / Q000473:pathology*
keywords: MRI, magnetic resonance imaging; MSA, magnetic susceptibility anisotropy; QSM, quantitative susceptibility mapping; STI, susceptibility tensor imaging; SWI, susceptibility weighted imaging; TBI, traumatic brain injury; hemorrhage; iron; multiple sclerosis; myelin; stroke