Journal ArticleDOI
Brain dysmyelination and recovery assessment by noninvasive in vivo diffusion tensor magnetic resonance imaging.
Laura A. Harsan,Patrick Poulet,Blandine Guignard,Jérôme Steibel,Nathalie Parizel,Paulo Loureiro de Sousa,Nelly Boehm,Daniel Grucker,M. Said Ghandour +8 more
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TLDR
It is shown clearly that myelination and axonal changes play a role in the degree of diffusion anisotropy, because FA was significantly decreased in dysmyelinated brain.Abstract:
Diffusion tensor magnetic resonance imaging (DT-MRI) was applied for in vivo quantification of myelin loss and regeneration. A transgenic mouse line (Oligo-TTK) expressing a truncated form of the herpes simplex virus 1 thymidine kinase gene (hsv1-tk) in oligodendrocytes was studied along with two induced phenotypes of myelin pathology. Myelin loss and axonal abnormalities differentially affect values of DT-MRI parameters in the brain of transgenic mice. Changes in the anisotropy of the white matter were assessed by calculating and mapping the radial (D perpendicular) and axial (D parallel) water diffusion to axonal tracts and fractional anisotropy (FA). A significant increase in D perpendicular attributed to the lack of myelin was observed in all selected brain white matter tracts in dysmyelinated mice. Lower D parallel values were consistent with the histological observation of axonal modifications, including reduced axonal caliber and overexpression of neurofilaments and III beta-tubulin. We show clearly that myelination and axonal changes play a role in the degree of diffusion anisotropy, because FA was significantly decreased in dysmyelinated brain. Importantly, myelin reparation during brain postnatal development induced a decrease in the magnitude of D( perpendicular) and an increase in FA compared with the same brain before recovery. The progressive increase in D parallel values was attributed to the gain in normal axonal morphology. This regeneration was confirmed by the detection of enlarged oligodendrocyte population, newly formed myelin sheaths around additional axons, and a gradual increase in axonal caliber.read more
Citations
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Journal ArticleDOI
Diffusion Tensor Imaging of the Brain
TL;DR: Diffusion tensor imaging (DTI) is a promising method for characterizing microstructural changes or differences with neuropathology and treatment and the biological mechanisms, acquisition, and analysis of DTI measurements are addressed.
Journal ArticleDOI
Principles of Diffusion Tensor Imaging and Its Applications to Basic Neuroscience Research
TL;DR: Diffusion tensor imaging (DTI) is a recently developed MRI technique that can measure macroscopic axonal organization in nervous system tissues and several applications are introduced, including visualization of axonal tracts in myelin and axonal injuries as well as human brain and mouse embryonic development.
Journal ArticleDOI
White matter integrity and cognition in chronic traumatic brain injury: a diffusion tensor imaging study
Marilyn F. Kraus,Teresa Susmaras,Benjamin P. Caughlin,Benjamin P. Caughlin,Corey J. Walker,John A. Sweeney,Deborah M. Little +6 more
TL;DR: Analysis of radial and axial diffusivity values suggested that all severities of TBI can result in a degree of axonal damage, while irreversible myelin damage was only apparent for moderate to severe TBI.
Journal ArticleDOI
Diffusion tensor imaging detects clinically important axonal damage after mild traumatic brain injury: a pilot study.
TL;DR: DTI detected significantly lower trace and elevated FA values in mild TBI subjects compared to controls, which are believed to represent axonal swelling, an early step in the process of axonal injury.
Journal ArticleDOI
White Matter Development in Adolescence: A DTI Study
TL;DR: Findings suggest that white matter connectivity supporting executive control of behavior is still immature in adolescence, as females showed earlier maturation of white matter integrity compared with males.
References
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MR diffusion tensor spectroscopy and imaging.
TL;DR: Once Deff is estimated from a series of NMR pulsed-gradient, spin-echo experiments, a tissue's three orthotropic axes can be determined and the effective diffusivities along these orthotropic directions are the eigenvalues of Deff.
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MR imaging of intravoxel incoherent motions: application to diffusion and perfusion in neurologic disorders.
TL;DR: A magnetic resonance (MR) method to image intravoxel incoherent motions (IVIMs) by using appropriate gradient pulses and nonuniform slow flow of cerebrospinal fluid appeared as a useful feature on IVIM images.
Journal ArticleDOI
Dysmyelination Revealed through MRI as Increased Radial (but Unchanged Axial) Diffusion of Water
Sheng-Kwei Song,Shu-Wei Sun,Shu-Wei Sun,Michael J. Ramsbottom,Chen Chang,John H. Russell,Anne H. Cross +6 more
TL;DR: The use of magnetic resonance diffusion tensor imaging to quantify the effect of dysmyelination on water directional diffusivities in brains of shiverer mice in vivo suggests that changes in lambda(perpendicular) and lambda(parallel) may potentially be used to differentiate myelin loss versus axonal injury.
Journal ArticleDOI
Diffusion tensor imaging detects and differentiates axon and myelin degeneration in mouse optic nerve after retinal ischemia.
TL;DR: The hypothesis that lambdaparallel and lambdaperpendicular hold promise as specific markers of axonal and myelin injury, respectively, and, further, that the coexistence of axon andMyelin degeneration does not confound this utility, are supported.
Journal ArticleDOI
Demyelination increases radial diffusivity in corpus callosum of mouse brain.
Sheng-Kwei Song,Jun E. Yoshino,Jun E. Yoshino,Tuan Q. Le,Shiow Jiuan Lin,Shu-Wei Sun,Anne H. Cross,Regina C. Armstrong,Regina C. Armstrong +8 more
TL;DR: In this article, the authors used diffusion tensor imaging (DTI) derived parameters to assess the extent of axonal damage, demyelination and axonal degeneration.