The Experts below are selected from a list of 15120 Experts worldwide ranked by ideXlab platform
Els Fieremans - One of the best experts on this subject based on the ideXlab platform.
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Diffusion Kurtosis Imaging Reveals Optic Tract Damage That Correlates with Clinical Severity in Glaucoma
2020 42nd Annual International Conference of the IEEE Engineering in Medicine & Biology Society (EMBC), 2020Co-Authors: Carlos Parra, Els Fieremans, Ji Won Bang, Gadi Wollstein, Joel S. Schuman, Kevin C. ChanAbstract:Glaucoma is a neurodegenerative disease of the visual system and is the leading cause of irreversible blindness worldwide. To date, its pathophysiological mechanisms remain unclear. This study evaluated the feasibility of advanced diffusion magnetic resonance imaging techniques for examining the microstructural environment of the visual pathway in glaucoma. While conventional diffusion tensor imaging (DTI) showed lower fractional anisotropy and higher directional diffusivities in the optic Tracts of glaucoma patients than healthy controls, diffusion kurtosis imaging (DKI) and the extended White Matter Tract integrity (WMTI) model indicated lower radial kurtosis, higher axial and radial diffusivities in the extra-axonal space, lower axonal water fraction, and lower tortuosity in the same regions in glaucoma patients. These findings suggest glial involvements apart from compromised axonal integrity in glaucoma. In addition, DKI and WMTI but not DTI parameters significantly correlated with clinical ophthalmic measures via optical coherence tomography and visual field perimetry testing. Taken together, DKI and WMTI provided sensitive and comprehensive imaging biomarkers for quantifying glaucomatous damage in the White Matter Tract across clinical severity complementary to DTI.
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White Matter Tract integrity an indicator of axonal pathology after mild traumatic brain injury
Journal of Neurotrauma, 2017Co-Authors: Sohae Chung, Els Fieremans, Dmitry S Novikov, Xiuyuan Wang, Nuri Erkut Kucukboyaci, Charles J Morton, James S Babb, Prin X Amorapanth, Farngyang Foo, Steven R FlanaganAbstract:AbsTract We seek to elucidate the underlying pathophysiology of injury sustained after mild traumatic brain injury (mTBI) using multi-shell diffusion magnetic resonance imaging, deriving compartmen...
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quantification of normal appearing White Matter Tract integrity in multiple sclerosis a diffusion kurtosis imaging study
Journal of Neurology, 2016Co-Authors: Ivan De Kouchkovsky, Els Fieremans, Lazar Fleysher, Joseph Herbert, Robert I Grossman, Matilde IngleseAbstract:Our aim was to characterize the nature and extent of pathological changes in the normal-appearing White Matter (NAWM) of patients with multiple sclerosis (MS) using novel diffusion kurtosis imaging-derived White Matter Tract integrity (WMTI) metrics and to investigate the association between these WMTI metrics and clinical parameters. Thirty-two patients with relapsing–remitting MS and 19 age- and gender-matched healthy controls underwent MRI and neurological examination. Maps of mean diffusivity, fractional anisotropy and WMTI metrics (intra-axonal diffusivity, axonal water fraction, tortuosity and axial and radial extra-axonal diffusivity) were created. Tract-based spatial statistics analysis was performed to assess for differences in the NAWM between patients and controls. A region of interest analysis of the corpus callosum was also performed to assess for group differences and to evaluate correlations between WMTI metrics and measures of disease severity. Mean diffusivity and radial extra-axonal diffusivity were significantly increased while fractional anisotropy, axonal water fraction, intra-axonal diffusivity and tortuosity were decreased in MS patients compared with controls (p values ranging from <0.001 to <0.05). Axonal water fraction in the corpus callosum was significantly associated with the expanded disability status scale score (ρ = −0.39, p = 0.035). With the exception of the axial extra-axonal diffusivity, all metrics were correlated with the symbol digits modality test score (p values ranging from 0.001 to <0.05). WMTI metrics are thus sensitive to changes in the NAWM of MS patients and might provide a more pathologically specific, clinically meaningful and practical complement to standard diffusion tensor imaging-derived metrics.
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White Matter Tract integrity metrics reflect the vulnerability of late myelinating Tracts in alzheimer s disease
NeuroImage: Clinical, 2014Co-Authors: Andreana Benitez, Els Fieremans, Jens H Jensen, Maria F Falangola, Ali Tabesh, Steven H Ferris, Joseph A HelpernAbstract:Post-mortem and imaging studies have observed that White Matter (WM) degenerates in a pattern inverse to myelin development, suggesting preferential regional vulnerabilities influencing cognitive decline in AD. This study applied novel WM Tract integrity (WMTI) metrics derived from diffusional kurtosis imaging (DKI) to examine WM tissue properties in AD within this framework. Using data from amnestic mild cognitive impairment (aMCI, n = 12), AD (n = 14), and normal control (NC; n = 15) subjects, mixed models revealed interaction effects: specific WMTI metrics of axonal density and myelin integrity (i.e. axonal water fraction, radial extra-axonal diffusivity) in late-myelinating Tracts (i.e. superior and inferior longitudinal fasciculi) changed in the course of disease, but were stable in the initial stages for early-myelinating Tracts (i.e. posterior limb of the internal capsule, cerebral peduncles). WMTI metrics in late-myelinating Tracts correlated with semantic verbal fluency, a cognitive function known to decline in AD. These findings corroborate the preferential vulnerability of late-myelinating Tracts, and illustrate an application of WMTI metrics to characterizing the regional course of WM changes in AD.
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novel White Matter Tract integrity metrics sensitive to alzheimer disease progression
American Journal of Neuroradiology, 2013Co-Authors: Els Fieremans, Andreana Benitez, Jens H Jensen, Maria F Falangola, Ali Tabesh, Rachael L Deardorff, Maria Vittoria Spampinato, James Babb, Dmitry S Novikov, Steven H FerrisAbstract:BACKGROUND AND PURPOSE: Along with cortical abnormalities, White Matter microstructural changes such as axonal loss and myelin breakdown are implicated in the pathogenesis of Alzheimer disease. Recently, a White Matter model was introduced that relates non-Gaussian diffusional kurtosis imaging metrics to characteristics of White Matter Tract integrity, including the axonal water fraction, the intra-axonal diffusivity, and the extra-axonal axial and radial diffusivities. MATERIALS AND METHODS: This study reports these White Matter Tract integrity metrics in subjects with amnestic mild cognitive impairment ( n = 12), Alzheimer disease ( n = 14), and age-matched healthy controls ( n = 15) in an effort to investigate their sensitivity, diagnostic accuracy, and associations with White Matter changes through the course of Alzheimer disease. RESULTS: With Tract-based spatial statistics and region-of-interest analyses, increased diffusivity in the extra-axonal space (extra-axonal axial and radial diffusivities) in several White Matter Tracts sensitively and accurately discriminated healthy controls from those with amnestic mild cognitive impairment (area under the receiver operating characteristic curve = 0.82–0.95), while widespread decreased axonal water fraction discriminated amnestic mild cognitive impairment from Alzheimer disease (area under the receiver operating characteristic curve = 0.84). Additionally, these White Matter Tract integrity metrics in the body of the corpus callosum were strongly correlated with processing speed in amnestic mild cognitive impairment ( r = |0.80–0.82|, P CONCLUSIONS: These findings have implications for the course and spatial progression of White Matter degeneration in Alzheimer disease, suggest the mechanisms by which these changes occur, and demonstrate the viability of these White Matter Tract integrity metrics as potential neuroimaging biomarkers of the earliest stages of Alzheimer disease and disease progression.
Massimo Filippi - One of the best experts on this subject based on the ideXlab platform.
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brain mr imaging in patients with lower motor neuron predominant disease
Radiology, 2016Co-Authors: Edoardo G Spinelli, Pilar M Ferraro, Nilo Riva, Yuri Matteo Falzone, Christian Lunetta, Federica Agosta, Andrea Falini, Giancarlo Comi, Massimo FilippiAbstract:The authors of this article investigated the patterns of cortical thinning and White Matter Tract damage in patients with lower motor neuron–predominant disease compared with healthy control subjects and those with classic amyotrophic lateral sclerosis and evaluated the relationship between brain structural changes and clinical and cognitive features.
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cognitive functions and White Matter Tract damage in amyotrophic lateral sclerosis a diffusion tensor Tractography study
American Journal of Neuroradiology, 2011Co-Authors: Lidia Sarro, Nilo Riva, Federica Agosta, Elisa Canu, A Prelle, Massimiliano Copetti, Gianna C Riccitelli, G Comi, Massimo FilippiAbstract:BACKGROUND AND PURPOSE: ALS is predominantly a disease of the motor system, but cognitive and behavioral symptoms also are observed. DT MR imaging is sensitive to microstructural changes occurring in WM Tracts of patients with ALS. In this study, we investigated the association between cognitive functions and extramotor WM Tract abnormalities in ALS patients. MATERIALS AND METHODS: DT MR imaging was obtained from 16 nondemented patients with ALS and 15 healthy controls. Patients with ALS underwent a neuropsychologic and behavioral evaluation. DT Tractography was used to asses the integrity of the CST, corpus callosum, and the major long-range association Tracts. The relationship between DT MR imaging metrics and cognitive functions was tested by using linear model analyses, adjusting for age and clinical disability. RESULTS: Eleven patients (69%) scored below the fifth percentile in at least 1 cognitive test, and 2 of them had a mild executive impairment. Performances at tests assessing attention and executive functions correlated with DT MR imaging metrics of the corpus callosum, CST, and long association WM Tracts bilaterally, including the cingulum, inferior longitudinal, inferior fronto-occipital, and uncinate fasciculi. Verbal learning and memory test scores were associated with fornix DT MR imaging values, whereas visual-spatial abilities correlated with left uncinate fractional anisotropy. CONCLUSIONS: WM Tract degeneration is associated with neuropsychologic deficits in patients with ALS. DT Tractography holds promise to gain insight into the role of the brain WM network abnormalities in the development of cognitive impairment in patients with ALS.
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White Matter damage in alzheimer disease and its relationship to gray Matter atrophy
Radiology, 2011Co-Authors: Federica Agosta, Michela Pievani, Stefania Sala, Cristina Geroldi, Giovanni B Frisoni, Samantha Galluzzi, Massimo FilippiAbstract:In Alzheimer disease, the observed patterns of White Matter abnormalities may reflect the advanced phase of a secondary degenerative process and an association, especially in the early phases of the disease, with primary White Matter Tract damage over and above gray Matter abnormalities.
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assessment of White Matter Tract damage in mild cognitive impairment and alzheimer s disease
Human Brain Mapping, 2010Co-Authors: Michela Pievani, Federica Agosta, Elisa Canu, Elisabetta Pagani, Stefania Sala, Martina Absinta, Cristina Geroldi, Rossana Ganzola, Giovanni B Frisoni, Massimo FilippiAbstract:Diffusion tensor MRI-based Tractography was used to investigate White Matter (WM) changes in the major limbic (i.e., fornix and cingulum) and cortico-cortical association pathways [i.e., the uncinate fasciculus, the inferior fronto-occipital fasciculus, the inferior longitudinal fasciculus (ILF), the superior longitudinal fasciculus, and the corpus callosum] in 25 Alzheimer's disease (AD) patients, 19 amnestic mild cognitive impairment (aMCI) patients, and 15 healthy controls (HC). Mean diffusivity (MD), fractional anisotropy (FA), as well as axial (DA) and radial (DR) diffusivities were measured for each Tract, using an atlas-based Tractography approach. The association of WM Tract integrity with hippocampal volume was also assessed. MD values were significantly different among groups in all WM Tracts (P values ranging from 0.002 to 0.03), except in the fornix (P = 0.06) and the inferior fronto-occipital fasciculus (P = 0.09). Conversely, FA was significantly different among groups in the fornix only (P = 0.02). DA values were significantly different among groups in all WM Tracts (P values ranging from 0.001 to 0.01), except in the fornix (P = 0.13) and the cingulum (P = 0.29). Significantly different DR values among groups were found in the fornix (P = 0.02) and the ILF (P = 0.01). In the fornix and cingulum, DR was significantly more increased than DA in both patient groups compared to HC. No difference in DA versus DR was found in cortico-cortical WM Tracts. DA values in the fornix were significantly correlated with the hippocampal volume. This study demonstrates a different pattern of WM involvement in the limbic and cortico-cortical association pathways in aMCI and AD patients.
Pratik Mukherjee - One of the best experts on this subject based on the ideXlab platform.
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data science ready multisite human diffusion mri White Matter Tract statistics
Scientific Data, 2020Co-Authors: Garikoitz Lermausabiaga, Pratik Mukherjee, Michael L Perry, Brian A WandellAbstract:The White Matter Tracts in the living human brain are critical for healthy function, and the diffusion MRI measured in these Tracts is correlated with diverse behavioral measures. The technical skills required to analyze diffusion MRI data are complex: data acquisition requires MRI sequence development and acquisition expertise, analyzing raw-data into meaningful summary statistics requires computational neuroimaging and neuroanatomy expertise. The human White Matter study field will advance faster if the Tract summaries are available in plain data-science-ready format for non-diffusion MRI experts, such as statisticians, computer graphic researchers or data scientists in general. Here, we share a curated and processed dataset from three different MRI centers in a format that is data-science ready. The multisite data we share include measures of within and between MRI center variation in White-Matter-Tract diffusion measurements. Along with the dataset description and summary statistics, we describe the state-of-the-art computational system that guarantees reproducibility and provenance from the original scanner output.
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pyramidal Tract maturation after brain injury in newborns with heart disease
Annals of Neurology, 2006Co-Authors: Pratik Mukherjee, Savannah C Partridge, Roland G Henry, Jeffrey I Berman, Daniel B Vigneron, Natalie N Charlton, Patrick S Mcquillen, Tom R Karl, James A BarkovichAbstract:Objective Our objective was to quantify White Matter Tract development in term newborns with congenital heart disease, a population at high risk for perioperative brain injury, using magnetic resonance imaging diffusion tensor Tractography (DTT). Methods Twenty-five newborns with congenital heart disease were imaged before and after surgery, with a median of 2 weeks between serial magnetic resonance imaging examinations. DTT was performed to segment bilateral pyramidal Tracts using semiautomated fiber tracking software, and manual region of interest measurements were taken for comparison. Results Significant maturational rates of increasing fractional anisotropy (median, 4.4% per week) and decreasing mean diffusivity (Dav) (median, −2.0% per week) in the pyramidal Tract were measured in infants without brain injury. Fractional anisotropy maturation rates were highest in newborns with normal scans, intermediate (median, 2.4% per week) in those with postoperative injury, and lowest (median, 0.9% per week) in those with preoperative injury, indicating a significant trend across brain injury groups (p = 0.015). Dav maturation rates did not differ across injury groups (p = 0.15). Manual region of interest measures showed greater variability in serial measurements, and no significant differences were identified between injury groups, suggesting that DTT may provide more sensitive measures. Interpretation DTT is feasible in term newborns and may help to characterize abnormal White Matter Tract development following acquired brain injury. Ann Neurol 2006
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diffusion tensor imaging serial quantitation of White Matter Tract maturity in premature newborns
NeuroImage, 2004Co-Authors: Savannah C Partridge, Pratik Mukherjee, Roland G Henry, Steven P Miller, Jeffrey I Berman, Hua Jin, Orit A Glenn, Donna M Ferriero, James A Barkovich, Daniel B VigneronAbstract:AbsTract Magnetic resonance diffusion tensor imaging (DTI) enables the discrimination of White Matter pathways before myelination is evident histologically or on conventional MRI. In this investigation, 14 premature neonates with no evidence of White Matter abnormalities by conventional MRI were studied with DTI. A custom MR-compatible incubator with a novel high sensitivity neonatal head coil and improved acquisition and processing techniques were employed to increase image quality and spatial resolution. The technical improvements enabled Tract-specific quantitative characterization of maturing White Matter, including several association Tracts and subcortical projection Tracts not previously investigated in neonates by MR. Significant differences were identified between White Matter pathways, with earlier maturing commissural Tracts of the corpus callosum, and deep projection Tracts of the cerebral peduncle and internal capsule exhibiting lower mean diffusivity ( D av ) and higher fractional anisotropy (FA) than later maturing subcortical projection and association pathways. Maturational changes in White Matter Tracts included reductions in D av and increases in FA with age due primarily to decreases in the two minor diffusion eigenvalues ( λ 2 and λ 3 ). This work contributes to the understanding of normal White Matter development in the preterm neonatal brain, an important step toward the use of DTI for the improved evaluation and treatment of White Matter injury of prematurity.
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diffusion weighted imaging of acute corticospinal Tract injury preceding wallerian degeneration in the maturing human brain
American Journal of Neuroradiology, 2003Co-Authors: Avi Mazumdar, Pratik Mukherjee, Jeffrey H Miller, Hiten Malde, Robert C MckinstryAbstract:BACKGROUND AND PURPOSE: Wallerian degeneration, the secondary degeneration of axons from cortical and subcortical injury, is associated with poor neurologic outcome. Since diffusion-weighted (DW) imaging is sensitive to early changes of cytotoxic edema, DW imaging may depict the acute injury to descending White Matter Tracts that precedes Wallerian degeneration; this injury is not visible on conventional CT or MR images in the maturing human brain. METHODS: Two neuroradiologists retrospectively analyzed clinical MR images in six children (aged 3 days to 5 months) with DW findings consistent with acute injury of the descending White Matter Tract due to territorial anterior or middle cerebral artery infarction. In five patients, images were obtained as a part of routine clinical evaluation. The remaining patient was a part of a prospective study of brain injury. Imaging findings were correlated with clinical outcomes. RESULTS: In all six patients, DW imaging performed 2-8 days after the onset of ischemia depicted injury to the descending White Matter Tract ipsilateral to the territorial infarct. Conventional MR images of the ipsilateral descending White Matter Tracts were abnormal in three patients. In all five patients for which follow-up results were available, the presence of DW changes was correlated with persistent neurologic disability. CONCLUSION: As shown in this retrospective analysis, DW imaging can depict acute injury to the descending White Matter Tract in neonates and infants, when conventional MR imaging may show normal findings. These DW findings likely precede the development of Wallerian degeneration, and they may portend a poor clinical outcome.
Federica Agosta - One of the best experts on this subject based on the ideXlab platform.
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brain mr imaging in patients with lower motor neuron predominant disease
Radiology, 2016Co-Authors: Edoardo G Spinelli, Pilar M Ferraro, Nilo Riva, Yuri Matteo Falzone, Christian Lunetta, Federica Agosta, Andrea Falini, Giancarlo Comi, Massimo FilippiAbstract:The authors of this article investigated the patterns of cortical thinning and White Matter Tract damage in patients with lower motor neuron–predominant disease compared with healthy control subjects and those with classic amyotrophic lateral sclerosis and evaluated the relationship between brain structural changes and clinical and cognitive features.
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cortical thinning and White Matter Tract damage in relation to cognition in motor neuron diseases p6 087
Neurology, 2015Co-Authors: Federica Agosta, Edoardo G Spinelli, Pilar M Ferraro, Nilo Riva, Elisa Canu, Massimiliano Copetti, Evelina Prudente, Adriano Chio, Sandro Iannaccone, Andrea FaliniAbstract:Objective: To assess the patterns of cortical thinning and White Matter (WM) Tract abnormalities in relation to cognition and behavioural symptoms in patients with motor neuron disease (MND). Methods: 101 patients with motor neuron disease (MND) and 56 healthy subjects were studied. Patients were classified into MND with a pure motor syndrome (MND-motor) and those with cognitive/behavioural symptoms (MND-plus). A surface-based morphometry analysis was used to assess cortical thickness. Corticospinal Tract (CST), corpus callosum (CC), and major association Tracts diffusion tensor (DT) metrics were obtained. A Random Forest (RF) approach was used to identify the set of image features correlated with cognitive/behavioural deficits. Results: There were 48 MND-motor and 53 MND-plus patients. Relative to controls, both patient groups showed cortical thinning of the bilateral precentral and postcentral gyri, cingulate cortex, inferior temporal and parietal areas. In all regions, there was a trend towards a more extensive involvement in MND-plus vs MND-motor. Both patient groups showed a damage of the motor CC fibers, but such a damage was greater in MND-plus cases. MND-plus patients also showed a severe involvement of the extra-motor WM Tracts bilaterally. RF analysis showed that the best predictors of cognitive deficits and behavioural symptoms in MND patients were the DT MRI metrics of the frontotemporal Tracts. Conclusions: Cortical thinning and WM degeneration are highly dependent upon neuropsychological and behavioural symptoms in patients with MND. WM Tract damage contributes to the severity of selective cognitive and behavioural manifestations more than cortical thinning. Study Supported by: Italian Ministry of Health (#RF-2010-2313220). Disclosure: Dr. Agosta has received personal compensation for activities with Biogen Idec and Serono Symposia International Foundation. Dr. Ferraro has nothing to disclose. Dr. Spinelli has nothing to disclose. Dr. Canu has nothing to disclose. Dr. Riva has nothing to disclose. Dr. Copetti has nothing to disclose. Dr. Prudente has nothing to disclose. Adriano Chio serves on a scientific advisory board for Biogen Idec, Cytokinetics and Italfamaco, Dr. Iannaccone has nothing to disclose. Dr. Falini has nothing to disclose. Dr. Comi has received personal compensation for activities with Teva, Novartis, Genzyme, Merck Serono, Biogen Idec, Bayer, Actelion Pharmaceuticals, Almirall, and Serono. Cure PSP, Alzheimer9s Drug Discovery Foundation, and the Jacques and Gloria Gossweiler
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cognitive functions and White Matter Tract damage in amyotrophic lateral sclerosis a diffusion tensor Tractography study
American Journal of Neuroradiology, 2011Co-Authors: Lidia Sarro, Nilo Riva, Federica Agosta, Elisa Canu, A Prelle, Massimiliano Copetti, Gianna C Riccitelli, G Comi, Massimo FilippiAbstract:BACKGROUND AND PURPOSE: ALS is predominantly a disease of the motor system, but cognitive and behavioral symptoms also are observed. DT MR imaging is sensitive to microstructural changes occurring in WM Tracts of patients with ALS. In this study, we investigated the association between cognitive functions and extramotor WM Tract abnormalities in ALS patients. MATERIALS AND METHODS: DT MR imaging was obtained from 16 nondemented patients with ALS and 15 healthy controls. Patients with ALS underwent a neuropsychologic and behavioral evaluation. DT Tractography was used to asses the integrity of the CST, corpus callosum, and the major long-range association Tracts. The relationship between DT MR imaging metrics and cognitive functions was tested by using linear model analyses, adjusting for age and clinical disability. RESULTS: Eleven patients (69%) scored below the fifth percentile in at least 1 cognitive test, and 2 of them had a mild executive impairment. Performances at tests assessing attention and executive functions correlated with DT MR imaging metrics of the corpus callosum, CST, and long association WM Tracts bilaterally, including the cingulum, inferior longitudinal, inferior fronto-occipital, and uncinate fasciculi. Verbal learning and memory test scores were associated with fornix DT MR imaging values, whereas visual-spatial abilities correlated with left uncinate fractional anisotropy. CONCLUSIONS: WM Tract degeneration is associated with neuropsychologic deficits in patients with ALS. DT Tractography holds promise to gain insight into the role of the brain WM network abnormalities in the development of cognitive impairment in patients with ALS.
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White Matter damage in alzheimer disease and its relationship to gray Matter atrophy
Radiology, 2011Co-Authors: Federica Agosta, Michela Pievani, Stefania Sala, Cristina Geroldi, Giovanni B Frisoni, Samantha Galluzzi, Massimo FilippiAbstract:In Alzheimer disease, the observed patterns of White Matter abnormalities may reflect the advanced phase of a secondary degenerative process and an association, especially in the early phases of the disease, with primary White Matter Tract damage over and above gray Matter abnormalities.
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assessment of White Matter Tract damage in mild cognitive impairment and alzheimer s disease
Human Brain Mapping, 2010Co-Authors: Michela Pievani, Federica Agosta, Elisa Canu, Elisabetta Pagani, Stefania Sala, Martina Absinta, Cristina Geroldi, Rossana Ganzola, Giovanni B Frisoni, Massimo FilippiAbstract:Diffusion tensor MRI-based Tractography was used to investigate White Matter (WM) changes in the major limbic (i.e., fornix and cingulum) and cortico-cortical association pathways [i.e., the uncinate fasciculus, the inferior fronto-occipital fasciculus, the inferior longitudinal fasciculus (ILF), the superior longitudinal fasciculus, and the corpus callosum] in 25 Alzheimer's disease (AD) patients, 19 amnestic mild cognitive impairment (aMCI) patients, and 15 healthy controls (HC). Mean diffusivity (MD), fractional anisotropy (FA), as well as axial (DA) and radial (DR) diffusivities were measured for each Tract, using an atlas-based Tractography approach. The association of WM Tract integrity with hippocampal volume was also assessed. MD values were significantly different among groups in all WM Tracts (P values ranging from 0.002 to 0.03), except in the fornix (P = 0.06) and the inferior fronto-occipital fasciculus (P = 0.09). Conversely, FA was significantly different among groups in the fornix only (P = 0.02). DA values were significantly different among groups in all WM Tracts (P values ranging from 0.001 to 0.01), except in the fornix (P = 0.13) and the cingulum (P = 0.29). Significantly different DR values among groups were found in the fornix (P = 0.02) and the ILF (P = 0.01). In the fornix and cingulum, DR was significantly more increased than DA in both patient groups compared to HC. No difference in DA versus DR was found in cortico-cortical WM Tracts. DA values in the fornix were significantly correlated with the hippocampal volume. This study demonstrates a different pattern of WM involvement in the limbic and cortico-cortical association pathways in aMCI and AD patients.
Zhou Zhou - One of the best experts on this subject based on the ideXlab platform.
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towards a comprehensive delineation of White Matter Tract related deformation
Journal of Neurotrauma, 2021Co-Authors: Zhou Zhou, Yuzhe Liu, Madelen Fahlstedt, Marios Georgiadis, Xianghao Zhan, Samuel J Raymond, Gerald A Grant, Svein Kleiven, David B Camarillo, Michael ZeinehAbstract:Finite element (FE) models of the human head are valuable instruments to explore the mechanobiological pathway from external loading, localized brain response, and resultant injury risks. The injury predictability of these models depends on the use of effective criteria as injury predictors. The FE-derived normal deformation along White Matter (WM) fiber Tracts (i.e., Tract-oriented strain) has recently been suggested as an appropriate predictor for axonal injury. However, the Tract-oriented strain only represents a partial depiction of the WM fiber Tract deformation. A comprehensive delineation of Tract-related deformation may improve the injury predictability of the FE head model by delivering new Tract-related criteria as injury predictors. Thus, the present study performed a theoretical strain analysis to comprehensively characterize the WM fiber Tract deformation by relating the strain tensor of the WM element to its embedded fiber Tract. Three new Tract-related strains with exact analytical solutions were proposed, measuring the normal deformation perpendicular to the fiber Tracts (i.e., Tract-perpendicular strain), and shear deformation along and perpendicular to the fiber Tracts (i.e., axial-shear strain and lateral-shear strain, respectively). The injury predictability of these three newly-proposed strain peaks along with the previously-used Tract-oriented strain peak and maximum principal strain (MPS) were evaluated by simulating 151 impacts with known outcome (concussion or non-concussion). The results preliminarily showed that four Tract-related strain peaks exhibited superior performance than MPS in discriminating concussion and non-concussion cases. This study presents a comprehensive quantification of WM Tract-related deformation and advocates the use of orientation-dependent strains as criteria for injury prediction, which may ultimately contribute to an advanced mechanobiological understanding and enhanced computational predictability of brain injury.
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towards a comprehensive delineation of White Matter Tract related deformation
bioRxiv, 2021Co-Authors: Zhou Zhou, Yuzhe Liu, Madelen Fahlstedt, Marios Georgiadis, Xianghao Zhan, Samuel J Raymond, Gerald A Grant, Svein Kleiven, David B CamarilloAbstract:Finite element (FE) models of the human head are valuable instruments to explore the mechanobiological pathway from external loading, localized brain response, and resultant injury risks. The injury predictability of these models depends on the use of effective criteria as injury predictors. The FE-derived normal deformation along White Matter (WM) fiber Tracts (i.e., Tract-oriented strain) has recently been suggested as an appropriate predictor for axonal injury. However, the Tract-oriented strain only represents a partial depiction of the WM fiber Tract deformation. A comprehensive delineation of Tract-related deformation may improve the injury predictability of the FE head model by delivering new Tract-related criteria as injury predictors. Thus, the present study performed a theoretical strain analysis to comprehensively characterize the WM fiber Tract deformation by relating the strain tensor of the WM element to its embedded fiber Tracts. Three new Tract-related strains were proposed, measuring the normal deformation vertical to the fiber Tracts (i.e., Tract-vertical strain), and shear deformation along and vertical to the fiber Tracts (i.e., axial-shear strain and lateral-shear strain, respectively). The injury predictability of these three newly-proposed strain peaks along with the previously-used Tract-oriented strain peak and maximum principal strain (MPS) were evaluated by simulating 151 impacts with known outcome (concussion or no-concussion). The results showed that four Tract-related strain peaks exhibit superior performance compared to MPS in discriminating concussion and non-concussion cases. This study presents a comprehensive quantification of WM Tract-related deformation and advocates the use of orientation-dependent strains as criteria for injury prediction, which may ultimately contribute to an advanced mechanobiological understanding and enhanced computational predictability of brain injury. HighlightO_LIDeformation of White matte fiber Tracts is directly related to brain injury, but only partially analyzed thus far. C_LIO_LIA theoretical derivation that comprehensively characterizes White Matter Tract-related deformation is conducted. C_LIO_LIAnalytical formulas of three novel Tract-related strains are presented. C_LIO_LITract-related strain peaks are better predictors for concussion than the maximum principal strain. C_LI
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White Matter Tract oriented deformation is dependent on real time axonal fiber orientation
Journal of Neurotrauma, 2021Co-Authors: Zhou Zhou, Gerald A Grant, Svein Kleiven, David B Camarillo, August G Domel, Michael ZeinehAbstract:Traumatic axonal injury (TAI) is a critical public health issue with its pathogenesis remaining largely elusive. Finite element (FE) head models are promising tools to bridge the gap between mechan...
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White Matter Tract oriented deformation is dependent on real time axonal fiber orientation
bioRxiv, 2020Co-Authors: Zhou Zhou, Gerald A Grant, Svein Kleiven, David B Camarillo, August G Domel, Michael ZeinehAbstract:Traumatic axonal injury (TAI) is a critical public health issue with its pathogenesis remaining largely elusive. Finite element (FE) head models are promising tools to bridge the gap between mechanical insult and localized brain response and resultant injury. In particular, the FE-derived deformation along the direction of White Matter (WM) Tracts (i.e., Tract-oriented strain) has been shown to be an appropriate predictor for TAI. However, the evolution of fiber orientation in time during the impact and its potential influence on Tract-oriented strain remained unknown. To address this question, the present study leveraged an embedded element approach to track real-time fiber orientation during impacts. A new scheme to calculate the Tract-oriented strain was proposed by projecting the strain tensors from pre-computed simulations along the temporal fiber direction instead of its static counterpart directly obtained from diffuse tensor imaging. The results revealed that incorporating the real-time fiber orientation not only altered the direction but also amplified the magnitude of the Tract-oriented strain, resulting in a generally more extended distribution and a larger volume ratio of WM exposed to high deformation along fiber Tracts. Results of this study provide important insights into how best to incorporate fiber orientation in head injury models and derive the WM Tract-oriented deformation from computational simulations, which is important for furthering our understanding of the underlying mechanisms of TAI.
