Diffusion tensor parameters and principal eigenvector coherence: Relation to b-value intervals and field strength

2013 ◽  
Vol 31 (5) ◽  
pp. 742-747 ◽  
Author(s):  
Ai Wern Chung ◽  
David L. Thomas ◽  
Roger J. Ordidge ◽  
Chris A. Clark
Keyword(s):  
Field Strength ◽  
Diffusion Tensor ◽  
B Value ◽  
Principal Eigenvector ◽  
Coherence Relation

scholarly journals Diffusion tensor imaging and fiber tractography of the median nerve at 1.5T: optimization of b value

2008 ◽  
Vol 38 (1) ◽  
pp. 51-59 ◽  
Author(s):  
Gustav Andreisek ◽  
Lawrence M. White ◽  
Andrea Kassner ◽  
George Tomlinson ◽  
Marshall S. Sussman
Keyword(s):  
Diffusion Tensor Imaging ◽  
Median Nerve ◽  
Diffusion Tensor ◽  
B Value ◽  
Fiber Tractography

Reduced connectivity in the uncinate fiber tract between the frontal cortex and limbic subcortical areas in social phobia

2011 ◽  
Vol 26 (S2) ◽  
pp. 182-182 ◽  
Author(s):  
J. Tröstl ◽  
R. Sladky ◽  
A. Hummer ◽  
C. Kraus ◽  
E. Moser ◽  
...  
Keyword(s):  
Social Phobia ◽  
Diffusion Tensor ◽  
Group Analysis ◽  
Structural Connectivity ◽  
B Value ◽  
Uncinate Fasciculus ◽  
Anatomical Connectivity ◽  
Isotropic Resolution ◽  
Image Position ◽  
Connectivity Strength

IntroductionSeveral fMRI and resting-state connectivity studies have demonstrated alterations in the limbic system and frontal areas in social anxiety disorder (SAD).AimsHere we used high-resolution whole-brain diffusion tensor imaging (DTI) to examine differences in anatomical connectivity between patients and controls in the white matter.MethodsWe examined 14 SAD patients (age 26.3 ± 9.0y) and 15 healthy controls (age 25.6 ± 3.3y) using DTI on a 3T Trio MRI scanner (Siemens, Germany). DTI acquisition with 1.6 mm isotropic resolution was performed in 30 directions and a maximum b-value of 800. Fractional anisotropy (FA) maps were obtained using FSL. Group analysis was performed in SPM8 (two sample t-test).ResultsThe figure shows a coronal slice through the uncinate fasciculus. Arrows point to areas where SAD patients show decreased FA-values compared to controls (p < 0.05). Note that these areas are limited to the uncinate fasciculus and are found bilaterally.ConclusionReduced FA-values indicate a reduction in anatomical connectivity strength. Our study thus clearly shows reduced connectivity strength in the uncinate fasciculus connecting frontal regions with limbic areas as the amygdalae and hippocampus. This reduced structural connectivity supports functional data demonstrating alterations of brain activation in the amygdala and prefrontal regions in social phobia.

scholarly journals High b-value and diffusion tensor imaging in a canine model of dysmyelination and brain maturation

NeuroImage ◽  
2011 ◽  
Vol 58 (3) ◽  
pp. 829-837 ◽  
Author(s):  
Yu-Chien Wu ◽  
Aaron S. Field ◽  
Ian D. Duncan ◽  
Alexey A. Samsonov ◽  
Yoichi Kondo ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
Diffusion Tensor ◽  
B Value ◽  
Canine Model ◽  
Brain Maturation ◽  
High B Value ◽  
And Diffusion

scholarly journals Microstructure Diffusion Scalar Measures from Reduced MRI Acquisitions

2019 ◽  
Author(s):  
Santiago Aja-Fernández ◽  
Rodrigo de Luis-García ◽  
Maryam Afzali ◽  
Malwina Molendowska ◽  
Tomasz Pieciak ◽  
...  
Keyword(s):  
Diffusion Tensor ◽  
State Of The Art ◽  
B Value ◽  
Computationally Efficient ◽  
Huge Amount ◽  
Average Diffusion ◽  
Efficient Alternative ◽  
Alternative Techniques ◽  
Dense Sampling ◽  
Diffusion Properties

AbstractIn diffusion MRI, the Ensemble Average diffusion Propagator (EAP) provides relevant microstructural information and meaningful descriptive maps of the white matter previously obscured by traditional techniques like the Diffusion Tensor. The direct estimation of the EAP, however, requires a dense sampling of the Cartesian q-space. Due to the huge amount of samples needed for an accurate reconstruction, more efficient alternative techniques have been proposed in the last decade. Even so, all of them imply acquiring a large number of diffusion gradients with different b-values. In order to use the EAP in practical studies, scalar measures must be directly derived, being the most common the return-to-origin probability (RTOP) and the return-to-plane and return-to-axis probabilities (RTPP, RTAP).In this work, we propose the so-called “Apparent Measures Using Reduced Acquisitions” (AMURA) to drastically reduce the number of samples needed for the estimation of diffusion properties. AMURA avoids the calculation of the whole EAP by assuming the diffusion anisotropy is roughly independent from the radial direction. With such an assumption, and as opposed to common multi-shell procedures based on iterative optimization, we achieve closed-form expressions for the measures using information from one single shell. This way, the new methodology remains compatible with standard acquisition protocols commonly used for HARDI (based on just one b-value). We report extensive results showing the potential of AMURA to reveal microstructural properties of the tissues compared to state of the art EAP estimators, and is well above that of Diffusion Tensor techniques. At the same time, the closed forms provided for RTOP, RTPP, and RTAP-like magnitudes make AMURA both computationally efficient and robust.

scholarly journals Determination of Optimum Combination of Voxel Size and b-value for Brain Diffusion Tensor Imaging

2017 ◽  
Vol 46 (1) ◽  
pp. 67-74 ◽  
Author(s):  
NUR HARTINI MOHD TAIB ◽  
WAN AHMAD KAMIL WAN ABDULLAH ◽  
IBRAHIM LUTFI SHUAIB ◽  
ENRICO MAGOSSO ◽  
SUZANA MAT ISA
Keyword(s):  
Diffusion Tensor Imaging ◽  
Diffusion Tensor ◽  
B Value ◽  
Optimum Combination ◽  
Voxel Size

scholarly journals White matter microstructural integrity across the adult lifespan: Combined perspective of diffusion tensor and kurtosis imaging

2021 ◽  
Author(s):  
Hiba Taha ◽  
Jordan A Chad ◽  
J. Jean Chen
Keyword(s):  
White Matter ◽  
Brain Aging ◽  
Diffusion Tensor ◽  
Diffusion Imaging ◽  
General Pattern ◽  
B Value ◽  
Diffusion Kurtosis Imaging ◽  
Adult Lifespan ◽  
Non Gaussian ◽  
Diffusion Kurtosis

Studies of healthy brain aging have reported diffusivity patterns associated with white matter degeneration using diffusion tensor imaging (DTI), which assumes that diffusion measured at the typical b-value (approximately 1000 s/mm2) is Gaussian. Diffusion kurtosis imaging (DKI) is an extension of DTI that measures non-Gaussian diffusion (kurtosis) to better capture microenvironmental changes by incorporating additional data at a higher b-value. In this study, using UK Biobank data (b values of 1000 and 2000 s/mm2), we investigate (1) the extent of novel information gained from adding diffusional kurtosis to diffusivity observations in aging, and (2) how conventional DTI metrics in aging compare with diffusivity metrics derived from DKI, which are corrected for kurtosis. We find a general pattern of lower kurtosis alongside higher diffusivity among older adults. We also find differences between diffusivity metrics derived from DTI and DKI, emphasizing the importance of accounting for non-Gaussian diffusion. This work highlights the utility of measuring diffusional kurtosis as a simple addition to conventional diffusion imaging of aging.

Sign in / Sign up

Export Citation Format

Share Document