Diffusion Tensor Imaging of the Brain

Alexander, Andrew L.; Lee, Jee Eun; Lazar, Mariana; Field, Aaron S.

doi:10.1016/j.nurt.2007.05.011

Cited by 2,298 publications

(2,192 citation statements)

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“…Therefore, the WM in the left hemisphere, being the substrate for a training‐induced plasticity, may be less affected by the disease (Saini et al., 2012; Scholz, Klein, Behrens, & Johansen‐Berg, 2009; Svatkova et al., 2015). While the contribution of both AD and RD on the MD changes point to the complex nature of WM changes with alterations in water content, myelin or axonal structure(Alexander et al., 2007; Saini et al., 2012), more widespread MD disturbance mostly contributed to RD abnormalities implies an abnormal myelination (Song et al., 2002) in the ET pathology. Similar to prior studies, we did not detect significant changes in FA, while demonstrating differences in diffusivity measures (Saini et al., 2012).…”

Section: Discussionmentioning

confidence: 99%

“…Similar to prior studies, we did not detect significant changes in FA, while demonstrating differences in diffusivity measures (Saini et al., 2012). Although FA represents a very robust WM measurement (Basser & Pierpaoli, 2011), it specifically shows a relative variation between the levels of diffusion measured in different direction (Alexander et al., 2007; Basser & Pierpaoli, 2011). FA may remain relatively stable even if individual diffusivity values undergo relatively large changes.…”

Section: Discussionmentioning

confidence: 99%

“…Diffusion tensor imaging (DTI) has been increasingly utilized as a noninvasive MRI technique, which allows quantifying microstructural substrate of disease‐related white matter (WM) alterations based on water movement (Alexander, Lee, Lazar, & Field, 2007; Basser & Pierpaoli, 2011). The three‐dimensional DTI tensor model provides fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivity values (Alexander et al., 2007; Pierpaoli & Basser, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…The three‐dimensional DTI tensor model provides fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivity values (Alexander et al., 2007; Pierpaoli & Basser, 1996). FA as the degree of anisotropy varies from 0 in nondirectional to 1 in highly oriented tissue (Alexander et al., 2007) and is influenced by the degree of myelination, axonal packing and size, coherence, and co‐linearity of fiber organization (Alexander et al., 2007). Changes in cellularity, edema, and/or necrosis affect MD, while RD and AD are sensitive to membrane coherence and axonal changes; respectively (Alexander et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

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White matter measures correlate with essential tremor severity—A pilot diffusion tensor imaging study

et al. 2018

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BackgroundAn evolving pathophysiological concept of essential tremor (ET) points to diffuse brain network involvement, which emphasizes the need to investigate white matter (WM) changes associated with motor symptoms of ET.ObjectivesTo investigate ET‐related WM changes and WM correlates of tremor severity using tremor clinical rating scales and accelerometry.MethodsTract‐based spatial statistics (TBSS) approach was utilized to compare 3 Tesla diffusion tensor imaging (DTI) data from 12 ET patients and 10 age‐ and gender‐matched healthy individuals. Clinical scales, tremor frequency and amplitude as measured by accelerometry were correlated with DTI data.Results ET patients demonstrated mean (MD) and radial diffusivity (RD) abnormalities in tracts involved in primary and associative motor functions such as bilateral corticospinal tracts, the superior longitudinal fascicles, and the corpus callosum but also in nonmotor regions including the inferior fronto‐occipital and longitudinal fascicles, cingulum bundles, anterior thalamic radiations, and uncinate fascicles. A combined tremor frequency and amplitude score correlated with RD and MD in extensive WM areas, which partially overlapped the regions that were associated with tremor frequency. No significant relationship was found between DTI measures and clinical rating scales scores.ConclusionsThe results show that ET‐related diffusion WM changes and their correlates with tremor severity are preferentially located in the primary and associative motor areas. In contrast, a relationship between WM was not detected with clinical rating scales. Accelerometry parameters may, therefore, serve as a potentially useful clinical measures that relate to WM deficits in ET.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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White matter measures correlate with essential tremor severity—A pilot diffusion tensor imaging study

et al. 2018

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“…Diffusivity (trace) is a measure for the amount of diffusion, which can be divided into an axial diffusivity component (λ , diffusion along the axons) and a radial diffusivity component (λ ⊥ , diffusion perpendicular to the axons). While λ corresponds to the first eigenvalue of the diffusion tensor (λ = λ 1 ), λ ⊥ is calculated by averaging the second and third eigenvalue: λ ⊥ = (λ 2 +λ 3 )/2 (Alexander et al, 2007). While diffusivity indicates the amount of diffusion, FA reflects the directionality of diffusion and is based on the relation between λ and λ ⊥ .…”

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confidence: 99%

White matter plasticity in the corticospinal tract of musicians: A diffusion tensor imaging study

et al. 2009

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With the advent of diffusion tensor imaging (DTI), the study of plastic changes in white matter architecture due to long-term practice has attracted increasing interest. Professional musicians provide an ideal model for investigating white matter plasticity because of their early onset of extensive auditory and sensorimotor training. We performed fiber tractography and subsequent voxelwise analysis, region of interest (ROI) analysis, and detailed slicewise analysis of diffusion parameters in the corticospinal tract (CST) on 26 professional musicians and a control group of 13 participants. All analyses resulted in significantly lower fractional anisotropy (FA) values in both the left and the right CST in the musician group. Furthermore, a right-greater-than-left asymmetry of FA was observed regardless of group. In the musician group, diffusivity was negatively correlated with the onset of musical training in childhood. A subsequent median split into an early and a late onset musician group (median=7 years) revealed increased diffusivity in the CST of the early onset group as compared to both the late onset group and the controls. In conclusion, these DTI-based findings might indicate plastic changes in white matter architecture of the CST in professional musicians. Our results imply that training-induced changes in diffusion characteristics of the axonal membrane may lead to increased radial diffusivity as reflected in decreased FA values. AbstractWith the advent of diffusion tensor imaging (DTI), the study of plastic changes in white matter architecture due to long-term practice has attracted increasing interest. Professional musicians provide an ideal model for investigating white matter plasticity because of their early onset of extensive auditory and sensorimotor training. We performed fiber tractography and subsequent voxelwise analysis, region of interest (ROI) analysis, and detailed slicewise analysis of diffusion parameters in the CST on 26 professional musicians and a control group of 13 participants. All analyses resulted in significantly lower FA values in both the left and the right CST in the musician group. Furthermore, a right-greater-than-left asymmetry of FA was observed regardless of group.In the musician group, diffusivity was negatively correlated with the onset of musical training in childhood. A subsequent median split into an early and a late onset musician group (median = 7 years) revealed increased diffusivity in the CST of the early onset group as compared with both the late onset group and the controls. In conclusion, these DTI-based findings might indicate plastic changes in white matter architecture of the CST in professional musicians. Our results imply that training-induced changes in diffusion characteristics of the axonal membrane may lead to increased radial diffusivity as reflected in decreased FA values.2

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Reduced Structural Connectivity of a Major Frontolimbic Pathway in Generalized Anxiety Disorder

Tromp

Grupe²,

Oathes³

et al. 2012

Arch Gen Psychiatry

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Context Emotion regulation deficits figure prominently in generalized anxiety disorder (GAD), as well as other anxiety and mood disorders. Research examining emotion regulation and top-down modulation has implicated reduced coupling of the amygdala with prefrontal and anterior cingulate cortex (ACC), suggesting altered frontolimbic white matter connectivity in GAD. Objective To investigate structural connectivity between ventral prefrontal/ACC areas and the amygdala in GAD, and to assess associations with functional connectivity between those areas. Design Participants underwent diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI) scans. Setting University magnetic resonance imaging facility. Participants Forty-nine GAD patients and 39 healthy volunteers, including a subset of 21 patients without comorbid Axis I diagnoses and 21 healthy volunteers matched for age, sex, and education. Main Outcome Measure Mean fractional anisotropy (FA) values in the left and right uncinate fasciculus, as measured by tract-based analysis for DTI data. Results Lower mean FA values in bilateral uncinate fasciculus indicated reduced frontolimbic structural connectivity in GAD. This reduction in uncinate fasciculus integrity was most pronounced for patients without comorbidity and was not observed in other white matter tracts. Across all subjects, higher FA values were associated with more negative functional coupling between the pregenual ACC and amygdala during the anticipation of aversion. Conclusions Decreased frontolimbic structural connectivity suggests a neural basis for emotion regulation deficits in GAD. The functional significance of these structural differences is underscored by decreased functional connectivity between the ACC and amygdala in subjects with reduced structural integrity of the uncinate fasciculus.

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Diffusion Tensor Imaging of the Brain

Cited by 2,298 publications

References 114 publications

White matter measures correlate with essential tremor severity—A pilot diffusion tensor imaging study

White matter measures correlate with essential tremor severity—A pilot diffusion tensor imaging study

White matter plasticity in the corticospinal tract of musicians: A diffusion tensor imaging study

Reduced Structural Connectivity of a Major Frontolimbic Pathway in Generalized Anxiety Disorder

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