Diffusion Anisotropy Measurement of Brain White Matter Is Affected by Voxel Size: Underestimation Occurs in Areas with Crossing Fibers

Oouchi, H.; Yamada, Kazuo; Sakai, Koji; Kizu, Osamu; Kubota, Takao; Ito, Hirotoshi; Nishimura, Tsunehiko

doi:10.3174/ajnr.a0488

Cited by 235 publications

(175 citation statements)

References 23 publications

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“…Therefore, the finding of distributed changes in axial diffusivity is more likely because of differences in the size, number, or arrangement of axons in the ketamine group, as opposed to differences in myelination. Although oligodendrocytes are thought to modulate a significant proportion of the radial diffusivity, this relationship does not always hold in situations where the local topology of white matter includes areas of crossing fibers or voxel size (Alexander and Seunarine, 2010;Oouchi et al, 2007). A possible explanation for observing only axial differences may be that localized glutamate excitotoxicity would affect oligodendrocytes and hence radial diffusivity in a focal region, but could potentially propagate over a much larger area while affecting axons.…”

Section: Discussionmentioning

confidence: 99%

Abnormalities in White Matter Microstructure Associated with Chronic Ketamine Use

Roberts

Curran

Friston

et al. 2013

Neuropsychopharmacol

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Ketamine is an N-methyl-D-aspartate (NMDA) receptor antagonist that has been found to induce schizophrenia-type symptoms in humans and is a potent and fast-acting antidepressant. It is also a relatively widespread drug of abuse, particularly in China and the UK. Acute administration has been well characterized, but the effect of extended periods of ketamine use-on brain structure in humansremains poorly understood. We measured indices of white matter microstructural integrity and connectivity in the brain of 16 ketamine users and 16 poly-drug-using controls, and we used probabilistic tractography to quantify changes in corticosubcortical connectivity associated with ketamine use. We found a reduction in the axial diffusivity profile of white matter in a right hemisphere network of white matter regions in ketamine users compared with controls. Within the ketamine-user group, we found a significant positive association between the connectivity profile between the caudate nucleus and the lateral prefrontal cortex and dissociative experiences. These findings suggest that chronic ketamine use may be associated with widespread disruption of white matter integrity, and white matter pathways between subcortical and prefrontal cortical areas may in part predict individual differences in dissociative experiences due to ketamine use.

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Section: Discussionmentioning

confidence: 99%

Abnormalities in White Matter Microstructure Associated with Chronic Ketamine Use

Roberts

Curran

Friston

et al. 2013

Neuropsychopharmacol

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show abstract

“…For instance, four non-diffusion (b 0 ) images were acquired during each scan session, then manually averaged to improve signal to noise ratio. Sixty non-collinear diffusion directions and isotropic voxels were used to improve angular resolution and data integrity (anisotropic voxels in diffusion acquisition can affect tensor modeling and artificially alter FA values (Oouchi et al, 2007)). Finally, well-established diffusion analysis methods were used to calculate FA value, and a rigorous statistical threshold was applied.…”

Section: Discussionmentioning

confidence: 99%

Reconciling Variable Findings of White Matter Integrity in Major Depressive Disorder

Choi

Holtzheimer

Franco

et al. 2013

Neuropsychopharmacol

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Diffusion tensor imaging (DTI) has been used to evaluate white matter (WM) integrity in major depressive disorder (MDD), with several studies reporting differences between depressed patients and controls. However, these findings are variable and taken from relatively small studies often using suboptimal analytic approaches. The presented DTI study examined WM integrity in large samples of medication-free MDD patients (n ¼ 134) and healthy controls (n ¼ 54) using voxel-based morphometry (VBM) and tract-based spatial statistics (TBSS) approaches, and rigorous statistical thresholds. Compared with health control subjects, MDD patients show no significant differences in fractional anisotropy, radial diffusivity, mean diffusivity, and axonal diffusivity with either the VBM or the TBSS approach. Our findings suggest that disrupted WM integrity does not have a major role in the neurobiology of MDD in this relatively large study using optimal imaging acquisition and analysis; however, this does not eliminate the possibility that certain patient subgroups show WM disruption associated with depression.

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“…2.0 × 2.0 × 2.0 mm 3 while trying to compensate for an acceptable SNR and scan time. We chose isotropic voxel based on its advantages over non-isotropic voxels (Jones et al 2002;Sasaki 2007;Oouchi et al 2007). We also chose the lowest and highest b-values (700 and 1200 s/mm 2 , respectively) which were testified from previous work that those are the optimal b-value for brain imaging as well as the common b-value used, which is 1000 s/mm 2 (Bougias &Tripoliti 2009;Mori 2007;Mukherjee et al 2008a).…”

Section: Discussion Imaging Parametersmentioning

confidence: 99%

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

Taib¹,

Abdullah²,

Shuaib³

et al. 2017

JSM

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Diffusion Anisotropy Measurement of Brain White Matter Is Affected by Voxel Size: Underestimation Occurs in Areas with Crossing Fibers

Cited by 235 publications

References 23 publications

Abnormalities in White Matter Microstructure Associated with Chronic Ketamine Use

Abnormalities in White Matter Microstructure Associated with Chronic Ketamine Use

Reconciling Variable Findings of White Matter Integrity in Major Depressive Disorder

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

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