Diffusion Tensor Imaging of the Brain

Department of Psychiatry, University of Wisconsin–Madison, Madison, Wisconsin, United States
Neurotherapeutics (Impact Factor: 5.05). 08/2007; 4(3):316-29. DOI: 10.1016/j.nurt.2007.05.011
Source: PubMed


Diffusion tensor imaging (DTI) is a promising method for characterizing microstructural changes or differences with neuropathology and treatment. The diffusion tensor may be used to characterize the magnitude, the degree of anisotropy, and the orientation of directional diffusion. This review addresses the biological mechanisms, acquisition, and analysis of DTI measurements. The relationships between DTI measures and white matter pathologic features (e.g., ischemia, myelination, axonal damage, inflammation, and edema) are summarized. Applications of DTI to tissue characterization in neurotherapeutic applications are reviewed. The interpretations of common DTI measures (mean diffusivity, MD; fractional anisotropy, FA; radial diffusivity, D
r; and axial diffusivity, D
a) are discussed. In particular, FA is highly sensitive to microstructural changes, but not very specific to the type of changes (e.g., radial or axial). To maximize the specificity and better characterize the tissue microstructure, future studies should use multiple diffusion tensor measures (e.g., MD and FA, or D
a and D

Download full-text


Available from: Mariana Lazar, Nov 23, 2014
    • "DHA plays a crucial role 719 in maintaining cortical neuronal integrity[101]. In healthy subjects supplementation with 720 DHA, EPA and vitamin E significantly attenuated grey matter volume loss in the 721 hippocampus and temporal brain regions[102]. These findings emphasize the ability of a 722 HFHC diet and LCPUFAs to affect grey matter structure and volume.Kullman et al. reported 723that obese individuals showed a decreased functional connectivity strength in the left insular 724 cortex[103]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Worldwide, the incidence of obesity is increasing at an alarming rate, and the number of children with obesity is especially worrisome. These developments raise concerns about the physical, psychosocial and cognitive consequences of obesity. It was shown that early dietary intake of arachidonic acid (ARA) and docosahexaenoic acid (DHA) can reduce the detrimental effects of later obesogenic feeding on lipid metabolism and adipogenesis in an animal model of mild obesity. In the present study, the effects of early dietary ARA and DHA on cognition and brain structure were examined in mildly obesogenic ApoE*3Leiden mouse model. We used cognitive tests and neuroimaging during early and later life. During their early development after weaning (4–13 weeks of age), mice were fed a chow diet or ARA and DHA-diet for eight weeks, and then switched to a high fat and high carbohydrates (HFHC) diet for 12 weeks (14–26 weeks of age). A HFHC-diet led to increased energy storage in white adipose tissue, increased cholesterol levels, decreased triglycerides levels, increased cerebral blood flow, and decreased functional connectivity between brain regions as well as cerebrovascular and grey matter integrity. ARA and DHA intake reduced the HFHC diet-induced increase in body weight, attenuated plasma triglycerides levels and improved cerebrovasculature, grey matter integrity and functional connectivity in later life. In conclusion, a HFHC diet causes adverse structural brain and metabolic adaptations, most of which can be averted by dietary ARA and DHA intake early in life supporting metabolic flexibility and cerebral integrity later in life.
    No preview · Article · Jan 2016
    • "The second and third eigenvalue λ2 and λ3 can be used to calculate the restricted perpendicular diffusivity (λ ┴ ) of water molecules. Physiological or pathological changes to structural WM features may influence the magnitudes of the eigenvalues (Alexander et al. 2007). Fractional anisotropy (FA), a measure of the directionality of water diffusion in WM fibres, indicates microstructural fibre integrity (Hasan et al. 2004). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Chronic methamphetamine (MA) use can lead to white matter (WM) changes and increased levels of aggression. While previous studies have examined WM abnormalities relating to cognitive impairment, associations between WM integrity and aggression in MA dependence remain unclear. Diffusion Tensor Imaging (DTI) was used to investigate WM changes in 40 individuals with MA dependence and 40 matched healthy controls. A region of interest (ROI) approach using tract based spatial statistics (TBSS) in FSL was performed. We compared fractional anisotropy (FA), mean diffusivity (MD), parallel diffusivity (λ║) and perpendicular diffusivity (λ┴) in WM tracts of the frontal brain. A relationship of WM with aggression scores from the Buss & Perry Questionnaire was investigated. Mean scores for anger (p < 0.001), physical aggression (p = 0.032) and total aggression (p = 0.021) were significantly higher in the MA group relative to controls. ROI analysis showed increased MD (U = 439.5, p = 0.001) and λ┴ (U = 561.5, p = 0.021) values in the genu of the corpus callosum, and increased MD (U = 541.5, p = 0.012) values in the right cingulum in MA dependence. None of the WM changes were significantly associated with aggression scores. This study provides evidence of frontal WM changes and increased levels of aggression in individuals with MA dependence. The lack of significant associations between WM and aggressive behaviour may reflect methodological issues in measuring such behaviour, or may indicate that the neurobiology of aggression is not simply correlated with WM damage but is more complex.
    No preview · Article · Dec 2015 · Metabolic Brain Disease
  • Source
    • "This makes it a powerful tool for noninvasive characterization of brain tissues. It is widely used for studying white matter (WM) organization and the microstructural changes that occur with neuropathology and following treatment [Alexander et al., 2007]. In the last 20 years DTI has been utilized to study WM architecture and integrity in both normal and diseased brains. "
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a novel method for fiber-based comparison of diffusion tensor imaging (DTI) scans of groups of subjects. The method entails initial preprocessing and fiber reconstruction by tractography of each brain in its native coordinate system. Several diffusion parameters are sampled along each fiber and used in subsequent comparisons. A spatial correspondence between subjects is established based on geometric similarity between fibers in a template set (several choices for template are explored), and fibers in all other subjects. Diffusion parameters between groups are compared statistically for each template fiber. Results are presented at single fiber resolution. As an initial exploratory step in neurological population studies this method points to the locations affected by the pathology of interest, without requiring a hypothesis. It does not make any grouping assumptions on the fibers and no manual intervention is needed. The framework was applied here to 18 healthy subjects and 23 amyotrophic lateral sclerosis (ALS) patients. The results are compatible with previous findings and with the tract based spatial statistics (TBSS) method. Hum Brain Mapp, 2015. © 2015 Wiley Periodicals, Inc.
    Full-text · Article · Oct 2015 · Human Brain Mapping
Show more