Abstract 221: Regional Vulnerability within White Matter tracts to White Matter Hyperintensities: a Diffusion Tensor Imaging Tractography Study

Stroke ◽  
2015 ◽  
Vol 46 (suppl_1) ◽  
Author(s):  
Pauline Maillard ◽  
Sudha Seshadri ◽  
Alexa Beiser ◽  
Jayandra Himali ◽  
Charles DeCarli
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Cognitive Decline ◽  
White Matter Hyperintensities ◽  
Diffusion Tensor ◽  
Brain Mri ◽  
Fiber Tracts ◽  
Regional Vulnerability ◽  
Increased Risk ◽  
The Impact

Background: Characterizing the impact of cerebral white matter (WM) damage on age related cognitive decline is of growing interest. White matter hyperintensities (WMH) and reduced microstructural WM integrity, as expressed by diffusion tensor imaging (DTI), have been associated with increased risk of clinically cognitive decline in the elderly, but the regional vulnerability within certain WM tracts to WMH is not well understood. Characterizing the implication and interactions of microstructural integrity and WMH within specific WM tracts would further elucidate mechanisms of cognitive decline in normal aging. Methods: 410 cognitively normal individuals from the Offspring Framingham Heart Study, aged 72.5±7.5 ([54.2; 104.9]), received a comprehensive clinical evaluation and brain MRI including FLAIR and DTI sequences. WM tractography was performed from DTI using FSL tools, resulting in 27 fiber tracts maps for each subject. WMHs were detected on FLAIR scans using a standardized protocol and coregistered to the subject DTI space. The mean fractional anisotrophy (mFA) within each tract was computed. Superimposition of WMH masks onto fiber tracts maps was used to calculate the overlap ratio of WMH (WMHor) within each tract. For each tract, mFA was regressed against the age and tract size and resulting residuals related to WMHor using a linear regression model. Results: The highest rates of WMHor were found within the thalamic radiations (range: [0- 28%]) and the inferior longitudinal fasciculi ([0- 29%]). Lower mFA was independently associated with larger WMHor within almost all association and projection fibers (p values<0.05). Correcting for the overall WMH burden did not significantly alter the results. Discussion: Regional mean FA has been previously associated with the overall WMH burden. We extended this finding by showing that, independently of the overall WM injury, microstructural WM integrity was associated with WMH within specific fiber tracts. Further investigations are needed to detangle the impact of specific tract disruption from that of more generalized subtle WM injury on cognitive decline.

scholarly journals Retrospective analysis of hemispheric structural network change as a function of location and size of glioma

2020 ◽  
Author(s):  
Shawn D’Souza ◽  
Lisa Hirt ◽  
David R Ormond ◽  
John A Thompson
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Temporal Lobe ◽  
Diffusion Tensor ◽  
Brain Regions ◽  
Structural Network ◽  
Tumour Location ◽  
The Impact ◽  
Tractography Data ◽  
Diffusion Tensor Imaging Tractography

Abstract Gliomas are neoplasms that arise from glial cell origin and represent the largest fraction of primary malignant brain tumours (77%). These highly infiltrative malignant cell clusters modify brain structure and function through expansion, invasion and intratumoral modification. Depending on the growth rate of the tumour, location and degree of expansion, functional reorganization may not lead to overt changes in behaviour despite significant cerebral adaptation. Studies in simulated lesion models and in patients with stroke reveal both local and distal functional disturbances, using measures of anatomical brain networks. Investigations over the last two decades have sought to use diffusion tensor imaging tractography data in the context of intracranial tumours to improve surgical planning, intraoperative functional localization, and post-operative interpretation of functional change. In this study, we used diffusion tensor imaging tractography to assess the impact of tumour location on the white matter structural network. To better understand how various lobe localized gliomas impact the topology underlying efficiency of information transfer between brain regions, we identified the major alterations in brain network connectivity patterns between the ipsilesional versus contralesional hemispheres in patients with gliomas localized to the frontal, parietal or temporal lobe. Results were indicative of altered network efficiency and the role of specific brain regions unique to different lobe localized gliomas. This work draws attention to connections and brain regions which have shared structural susceptibility in frontal, parietal and temporal lobe glioma cases. This study also provides a preliminary anatomical basis for understanding which affected white matter pathways may contribute to preoperative patient symptomology.

White Matter Alteration Following SWAT Explosive Breaching Training and the Moderating Effect of a Neck Collar Device: A DTI and NODDI Study

2021 ◽  
Author(s):  
Weihong Yuan ◽  
Jonathan Dudley ◽  
Alexis B Slutsky-Ganesh ◽  
James Leach ◽  
Pete Scheifele ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Diffusion Tensor ◽  
Moderating Effect ◽  
Significant Group ◽  
Blast Exposure ◽  
Diffusion Weighted ◽  
Weighted Data ◽  
The Right ◽  
The Impact

ABSTRACT Introduction Special Weapons and Tactics (SWAT) personnel who practice breaching with blast exposure are at risk for blast-related head trauma. We aimed to investigate the impact of low-level blast exposure on underlying white matter (WM) microstructure based on diffusion tensor imaging (DTI) and neurite orientation and density imaging (NODDI) in SWAT personnel before and after breacher training. Diffusion tensor imaging is an advanced MRI technique sensitive to underlying WM alterations. NODDI is a novel MRI technique emerged recently that acquires diffusion weighted data from multiple shells modeling for different compartments in the microstructural environment in the brain. We also aimed to evaluate the effect of a jugular vein compression collar device in mitigating the alteration of the diffusion properties in the WM as well as its role as a moderator on the association between the diffusion property changes and the blast exposure. Materials and Methods Twenty-one SWAT personnel (10 non-collar and 11 collar) completed the breacher training and underwent MRI at both baseline and after blast exposure. Diffusion weighted data were acquired with two shells (b = 1,000, 2,000 s/mm2) on 3T Phillips scanners. Diffusion tensor imaging metrices, including fractional anisotropy, mean, axial, and radial diffusivity, and NODDI metrics, including neurite density index (NDI), isotropic volume fraction (fiso), and orientation dispersion index, were calculated. Tract-based spatial statistics was used in the voxel-wise statistical analysis. Post hoc analyses were performed for the quantification of the pre- to post-blast exposure diffusion percentage change in the WM regions with significant group difference and for the assessment of the interaction of the relationship between blast exposure and diffusion alteration. Results The non-collar group exhibited significant pre- to post-blast increase in NDI (corrected P &lt; .05) in the WM involving the right internal capsule, the right posterior corona radiation, the right posterior thalamic radiation, and the right sagittal stratum. A subset of these regions showed significantly greater alteration in NDI and fiso in the non-collar group when compared with those in the collar group (corrected P &lt; .05). In addition, collar wearing exhibited a significant moderating effect for the alteration of fiso for its association with average peak pulse pressure. Conclusions Our data provided initial evidence of the impact of blast exposure on WM diffusion alteration based on both DTI and NODDI. The mitigating effect of WM diffusivity changes and the moderating effect of collar wearing suggest that the device may serve as a promising solution to protect WM against blast exposure.

scholarly journals White matter hyperintensities are common in midlife and already associated with cognitive decline

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Tracy d’Arbeloff ◽  
Maxwell L Elliott ◽  
Annchen R Knodt ◽  
Tracy R Melzer ◽  
Ross Keenan ◽  
...  
Keyword(s):  
White Matter ◽  
Cognitive Decline ◽  
White Matter Hyperintensities ◽  
Clinical Symptoms ◽  
White Matter Hyperintensity ◽  
Dementia Prevention ◽  
Increased Risk ◽  
Weighted Magnetic Resonance Imaging ◽  
Intervention Trials ◽  
The Brain

Abstract White matter hyperintensities proliferate as the brain ages and are associated with increased risk for cognitive decline as well as Alzheimer’s disease and related dementias. As such, white matter hyperintensities have been targeted as a surrogate biomarker in intervention trials with older adults. However, it is unclear at what stage of aging white matter hyperintensities begin to relate to cognition and if they may be a viable target for early prevention. In the Dunedin Study, a population-representative cohort followed since birth, we measured white matter hyperintensities in 843 45-year-old participants using T2-weighted magnetic resonance imaging and we assessed cognitive decline from childhood to midlife. We found that white matter hyperintensities were common at age 45 and that white matter hyperintensity volume was modestly associated with both lower childhood (ß = −0.08, P = 0.013) and adult IQ (ß=−0.15, P &lt; 0.001). Moreover, white matter hyperintensity volume was associated with greater cognitive decline from childhood to midlife (ß=−0.09, P &lt; 0.001). Our results demonstrate that a link between white matter hyperintensities and early signs of cognitive decline is detectable decades before clinical symptoms of dementia emerge. Thus, white matter hyperintensities may be a useful surrogate biomarker for identifying individuals in midlife at risk for future accelerated cognitive decline and selecting participants for dementia prevention trials.

Diffusion Tensor Imaging and Fiber Tractography

2009 ◽  
pp. 229-246
Author(s):  
Evanthia E. Tripoliti ◽  
Dimitrios I. Fotiadis ◽  
Konstantia Veliou
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
Diffusion Tensor ◽  
Brain Regions ◽  
Cerebral White Matter ◽  
Tissue Microstructure ◽  
Diffusion Weighted Images ◽  
Fiber Tracts ◽  
Diffusion Weighted ◽  
Magnetic Resonance Imaging Mri

Diffusion Tensor Imaging (DTI) is a magnetic resonance imaging (MRI) modality which can significantly improve our understanding of the brain structures and neural connectivity. DTI measures are thought to be representative of brain tissue microstructure and are particularly useful for examining organized brain regions, such as white matter tract areas. DTI measures the water diffusion tensor using diffusion weighted pulse sequences which are sensitive to microscopic random water motion. The resulting diffusion weighted images (DWI) display and allow quantification of how water diffuses along axes or diffusion encoding directions. This can help to measure and quantify the tissue’s orientation and structure, making it an ideal tool for examining cerebral white matter and neural fiber tracts. In this chapter the authors discuss the theoretical aspects of DTI, the information that can be extracted from DTI data, and the use of the extracted information for the reconstruction of fiber tracts and the diagnosis of a disease. In addition, a review of known fiber tracking algorithms is presented.

White matter hyperintensities and cognitive performance in adult patients with bipolar I, bipolar II, and major depressive disorders

2014 ◽  
Vol 29 (4) ◽  
pp. 226-232 ◽  
Author(s):  
T. Kieseppä ◽  
R. Mäntylä ◽  
A. Tuulio-Henriksson ◽  
K. Luoma ◽  
O. Mantere ◽  
...  
Keyword(s):  
White Matter ◽  
White Matter Hyperintensities ◽  
Structural Equation Models ◽  
Brain Mri ◽  
Path Model ◽  
Control Group ◽  
Coefficient Estimate ◽  
Major Depressive ◽  
Brain White Matter ◽  
Increased Risk

AbstractPurpose:We evaluate for the first time the associations of brain white matter hyperintensities (WMHs) on magnetic resonance imaging (MRI) with neuropsychological variables among middle-aged bipolar I (BPI), II (BPII) and major depressive disorder (MDD) patients and controls using a path model.Methods:Thirteen BPI, 15 BPII, 16 MDD patients, and 21 controls underwent brain MRI and a neuropsychological examination. Two experienced neuroradiologists evaluated WMHs on the MRI scans. We constructed structural equation models to test the strength of the associations between deep WMH (DWMH) grade, neuropsychological performance and diagnostic group.Results:Belonging in the BPI group as opposed to the control group predicted higher DWMH grade (coefficient estimate 1.13, P = 0.012). The DWMH grade independently predicted worse performance on the Visual Span Forward test (coefficient estimate −0.48, P = 0.002). Group effects of BPI and MDD were significant in predicting poorer performance on the Digit Symbol test (coefficient estimate −5.57, P = 0.016 and coefficient estimate −5.66, P = 0.034, respectively).Limitations:Because of the small number of study subjects in groups, the negative results must be considered with caution.Conclusions:Only BPI patients had an increased risk for DWMHs. DWMHs were independently associated with deficits in visual attention.

To Exclude or Not To Exclude: Further Examination of the Influence of White Matter Hyperintensities in Diffusion Tensor Imaging Research

2014 ◽  
Vol 31 (2) ◽  
pp. 198-205 ◽  
Author(s):  
Rael T. Lange ◽  
Jason R. Shewchuk ◽  
Manraj K.S. Heran ◽  
Alexander Rauscher ◽  
Michael Jarrett ◽  
...  
Keyword(s):  
Diffusion Tensor Imaging ◽  
White Matter ◽  
White Matter Hyperintensities ◽  
Diffusion Tensor ◽  
Imaging Research
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