scholarly journals Anomalous water dynamics in brain: a combined diffusion magnetic resonance imaging and neutron scattering investigation

2019 ◽  
Vol 16 (157) ◽  
pp. 20190186 ◽  
Author(s):  
F. Natali ◽  
C. Dolce ◽  
J. Peters ◽  
C. Stelletta ◽  
B. Demé ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Neutron Scattering ◽  
Brain Tissue ◽  
Diffusion Magnetic Resonance Imaging ◽  
Water Diffusion ◽  
Atomic Scale ◽  
Brain Diseases ◽  
Resonance Imaging ◽  
Diffusion In Brain

Water diffusion is an optimal tool for investigating the architecture of brain tissue on which modern medical diagnostic imaging techniques rely. However, intrinsic tissue heterogeneity causes systematic deviations from pure free-water diffusion behaviour. To date, numerous theoretical and empirical approaches have been proposed to explain the non-Gaussian profile of this process. The aim of this work is to shed light on the physics piloting water diffusion in brain tissue at the micrometre-to-atomic scale. Combined diffusion magnetic resonance imaging and first pioneering neutron scattering experiments on bovine brain tissue have been performed in order to probe diffusion distances up to macromolecular separation. The coexistence of free-like and confined water populations in brain tissue extracted from a bovine right hemisphere has been revealed at the micrometre and atomic scale. The results are relevant for improving the modelling of the physics driving intra- and extracellular water diffusion in brain, with evident benefit for the diffusion magnetic resonance imaging technique, nowadays widely used to diagnose, at the micrometre scale, brain diseases such as ischemia and tumours.

scholarly journals Diffusion Magnetic Resonance Imaging Study of a Rat Hippocampal Slice Model for Acute Brain Injury

2003 ◽  
Vol 23 (12) ◽  
pp. 1461-1470 ◽  
Author(s):  
Timothy M. Shepherd ◽  
Peter E. Thelwall ◽  
Stephen J. Blackband ◽  
Brian R. Pike ◽  
Ronald L. Hayes ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Brain Injury ◽  
Magnetic Resonance ◽  
Diffusion Magnetic Resonance Imaging ◽  
Water Diffusion ◽  
Acute Brain Injury ◽  
Acute Injury ◽  
Cell Swelling ◽  
Resonance Imaging ◽  
B Values

Diffusion magnetic resonance imaging (MRI) provides a surrogate marker of acute brain pathology, yet few studies have resolved the evolution of water diffusion changes during the first 8 hours after acute injury, a critical period for therapeutic intervention. To characterize this early period, this study used a 17.6-T wide-bore magnet to measure multicomponent water diffusion at high b-values (7 to 8,080 s/mm2) for rat hippocampal slices at baseline and serially for 8 hours after treatment with the calcium ionophore A23187. The mean fast diffusing water fraction (Ffast) progressively decreased for slices treated with 10-μmol/L A23187 (—20.9 ± 6.3% at 8 hours). Slices treated with 50-μmol/L A23187 had significantly reduced Ffast 80 minutes earlier than slices treated with 10-μmol/L A23187 (P < 0.05), but otherwise, the two doses had equivalent effects on the diffusion properties of tissue water. Correlative histologic analysis showed dose-related selective vulnerability of hippocampal pyramidal neurons (CA1 > CA3) to pathologic swelling induced by A23187, confirming that particular intravoxel cell populations may contribute disproportionately to water diffusion changes observed by MRI after acute brain injury. These data suggest diffusion-weighted images at high b-values and the diffusion parameter Ffast may be highly sensitive correlates of cell swelling in nervous issue after acute injury.

Inferring Structural and Architectural Features of Brain Tissue from DT-MRI Measurements

CNS Spectrums ◽  
2002 ◽  
Vol 7 (7) ◽  
pp. 510-515 ◽  
Author(s):  
Carlo Pierpaoli
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Brain Tissue ◽  
Diffusion Tensor ◽  
Imaging Modality ◽  
Magnetization Transfer ◽  
Biological Tissues ◽  
Water Diffusion ◽  
Proton Density ◽  
Resonance Imaging

ABSTRACTDiffusion tensor magnetic resonance imaging is an imaging modality that measures the diffusion properties of water molecules in tissues noninvasively. Water diffusion is affected by tissue constituents, such as macromolecules, membranes, organelles, as well as by tissue microstructure, architecture, and organization. From the quantities measured with diffusion tensor-magnetic resonance imaging, one can infer information about brain tissue that cannot be obtained using conventional, compositional-based (eg, proton density and chemical spectroscopy), or relaxometry-based (eg, magnetization transfer, T1, T2, and T2*) magnetic resonance imaging methods. Understanding the relationship between a measured water diffusion pattern and the underlying histological features of the tissue, however, is not simple. In the absence of a robust and comprehensive model of water diffusivity in biological tissues, the biological interpretation of diffusion measurements relies on empirical evidence. Herein, the properties of several diffusion tensor-derived quantities are reviewed, together with the experimental evidence that helps clarify their relationship with the underlying properties of brain tissue.

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