scholarly journals Dedicated diffusion phantoms for the investigation of free water elimination and mapping: insights into the influence of T 2 relaxation properties

2020 ◽  
Vol 33 (4) ◽  
Author(s):  
Ezequiel Farrher ◽  
Farida Grinberg ◽  
Li‐Wei Kuo ◽  
Kuan‐Hung Cho ◽  
Richard P. Buschbeck ◽  
...  
Keyword(s):  
Free Water ◽  
Relaxation Properties ◽  
Water Elimination

Characterizing Peritumoral Tissue Using DTI-Based Free Water Elimination

2019 ◽  
pp. 123-131 ◽  
Author(s):  
Abdol Aziz Ould Ismail ◽  
Drew Parker ◽  
Moises Hernandez-Fernandez ◽  
Steven Brem ◽  
Simon Alexander ◽  
...  
Keyword(s):  
Free Water ◽  
Water Elimination ◽  
Peritumoral Tissue

scholarly journals Diffusion kurtosis imaging with free water elimination: A bayesian estimation approach

2018 ◽  
Vol 80 (2) ◽  
pp. 802-813 ◽  
Author(s):  
Quinten Collier ◽  
Jelle Veraart ◽  
Ben Jeurissen ◽  
Floris Vanhevel ◽  
Pim Pullens ◽  
...  
Keyword(s):  
Bayesian Estimation ◽  
Free Water ◽  
Diffusion Kurtosis Imaging ◽  
Water Elimination ◽  
Diffusion Kurtosis

scholarly journals A diffusion model‐free framework with echo time dependence for free‐water elimination and brain tissue microstructure characterization

2018 ◽  
Vol 80 (5) ◽  
pp. 2155-2172 ◽  
Author(s):  
Miguel Molina‐Romero ◽  
Pedro A. Gómez ◽  
Jonathan I. Sperl ◽  
Michael Czisch ◽  
Philipp G. Sämann ◽  
...  
Keyword(s):  
Time Dependence ◽  
Brain Tissue ◽  
Diffusion Model ◽  
Free Water ◽  
Microstructure Characterization ◽  
Tissue Microstructure ◽  
Model Free ◽  
Water Elimination ◽  
Echo Time

scholarly journals Opposing white matter microstructure abnormalities in 22q11.2 deletion and duplication carriers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Johanna Seitz-Holland ◽  
Monica Lyons ◽  
Leila Kushan ◽  
Amy Lin ◽  
Julio E. Villalon-Reina ◽  
...  
Keyword(s):  
White Matter ◽  
Psychiatric Morbidity ◽  
Free Water ◽  
Water Model ◽  
22Q11.2 Deletion ◽  
Tissue Properties ◽  
Diffusion Weighted Images ◽  
Diffusion Weighted ◽  
Water Elimination ◽  
Number Variation

AbstractDeletions and duplications at the 22q11.2 locus are associated with significant neurodevelopmental and psychiatric morbidity. Previous diffusion-weighted magnetic resonance imaging (MRI) studies in 22q11.2 deletion carriers (22q-del) found nonspecific white matter (WM) abnormalities, characterized by higher fractional anisotropy. Here, utilizing novel imaging and processing methods that allow separation of signal contribution from different tissue properties, we investigate whether higher anisotropy is driven by (1) extracellular changes, (2) selective degeneration of secondary fibers, or (3) volumetric differences. We further, for the first time, investigate WM microstructure in 22q11.2 duplication carriers (22q-dup). Multi-shell diffusion-weighted images were acquired from 26 22q-del, 19 22q-dup, and 18 healthy individuals (HC). Images were fitted with the free-water model to estimate anisotropy following extracellular free-water elimination and with the novel BedpostX model to estimate fractional volumes of primary and secondary fiber populations. Outcome measures were compared between groups, with and without correction for WM and cerebrospinal fluid (CSF) volumes. In 22q-del, anisotropy following free-water elimination remained significantly higher compared with controls. BedpostX did not identify selective secondary fiber degeneration. Higher anisotropy diminished when correcting for the higher CSF and lower WM volumes. In contrast, 22q-dup had lower anisotropy and greater extracellular space than HC, not influenced by macrostructural volumes. Our findings demonstrate opposing effects of reciprocal 22q11.2 copy-number variation on WM, which may arise from distinct pathologies. In 22q-del, microstructural abnormalities may be secondary to enlarged CSF space and more densely packed WM. In 22q-dup, we see evidence for demyelination similar to what is commonly observed in neuropsychiatric disorders.

Free water elimination and mapping from diffusion MRI

2009 ◽  
Vol 62 (3) ◽  
pp. 717-730 ◽  
Author(s):  
Ofer Pasternak ◽  
Nir Sochen ◽  
Yaniv Gur ◽  
Nathan Intrator ◽  
Yaniv Assaf
Keyword(s):  
Diffusion Mri ◽  
Free Water ◽  
Water Elimination

scholarly journals Spatiotemporal characterisation of ischaemic lesions in transient stroke animal models using diffusion free water elimination and mapping MRI with echo time dependence

NeuroImage ◽  
2021 ◽  
pp. 118605
Author(s):  
Ezequiel Farrher ◽  
Chia-Wen Chiang ◽  
Kuan-Hung Cho ◽  
Farida Grinberg ◽  
Richard P. Buschbeck ◽  
...  
Keyword(s):  
Animal Models ◽  
Time Dependence ◽  
Free Water ◽  
Water Elimination ◽  
Echo Time

scholarly journals [Re] Optimization of a free water elimination two-compartment model for diffusion tensor imaging

2017 ◽  
Author(s):  
Rafael Neto Henriques ◽  
Ariel Rokem ◽  
Eleftherios Garyfallidis ◽  
Samuel St-Jean ◽  
Eric Thomas Peterson ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
Diffusion Mri ◽  
Diffusion Tensor ◽  
Free Water ◽  
Compartment Model ◽  
B Values ◽  
Brain White Matter ◽  
Diffusion Weighted ◽  
Two Compartment Model ◽  
Water Elimination

Typical diffusion-weighted imaging (DWI) is susceptible to partial volume effects: different types of tissue that reside in the same voxel are inextricably mixed. For instance, in regions near the cerebral ventricles or parenchyma, fractional anisotropy (FA) from diffusion tensor imaging (DTI) may be underestimated, due to partial volumes of cerebral spinal fluid (CSF). Free-water can be suppressed by adding parameters to diffusion MRI models. For example, the DTI model can be extended to separately take into account the contributions of tissue and CSF, by representing the tissue compartment with an anisotropic diffusion tensor and the CSF compartment as an isotropic free water diffusion coefficient. Recently, two procedures were proposed to fit this two-compartment model to diffusion-weighted data acquired for at least two different non-zero diffusion MRI b-values. In this work, the first open-source reference implementation of these procedures is provided. In addition to presenting some methodological improvements that increase model fitting robustness, the free water DTI procedures are re-evaluated using Monte-Carlo multicompartmental simulations. Analogous to previous studies, our results show that the free water elimination DTI model is able to remove confounding effects of fast diffusion for typical FA values of brain white matter. In addition, this study confirms that for a fixed scanning time the fwDTI fitting procedures have better performance when data is acquired for diffusion gradient direction evenly distributed along two b-values of 500 and 1500 s/mm2.

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