The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Helen E Darceuil - One of the best experts on this subject based on the ideXlab platform.
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connectivity based parcellation of the macaque frontal cortex and its relation with the cytoarchitectonic distribution described in current atlases
Brain Structure & Function, 2017Co-Authors: Helen E Darceuil, Leonardo Cerliani, Michel Thiebaut De SchottenAbstract:Through its connectivity with the rest of the brain, a cortical region constrains its function. The advent of MRI methods such as diffusion-weighted imaging Tractography allows us to estimate whole-brain anatomical connectivity at multiple seed regions in the same subject. This makes it possible to use data-driven techniques to define the spatial boundaries between adjacent brain regions characterized by sharply different connectivity. This approach has recently been employed to identify connectivity-based subdivisions of the human frontal lobe bearing an apparent similarity with cytoarchitectural subdivisions. However, the spatial relationships between the boundaries of cytoarchitectonic areas and Tractography-based subdivisions remain largely hypothetical. In this work we present the first Tractography-based parcellation of the frontal lobes in macaques. Diffusion-weighted data for Tractography were acquired on ex vivo macaque brain specimens, ruling out the presence of various sources of noise present in acquisitions on living subjects. An unsupervised multivariate technique consistently showed the presence of 11 Tractography-driven subdivisions in the frontal lobe across specimens. Comparison with several microstructural atlases suggested a heterogeneous relationship of these subdivisions with cytoarchitectonic areas: caudal frontal, medial and orbitofronal subdivisions featured the most consistent relationship between modalities, while lateral prefrontal subdivisions mostly differed from atlas-based cytoarchitectonic subdivisions. Other subdivisions were reminiscent of the organization of anatomical projections of the caudal motor cortex, as well as of the intrinsic orbitofrontal networks. Hence, although some cytoarchitectural and connectivity-based subdivisions share a similar spatial distribution, they should not necessarily be considered as equivalent. Instead, connectivity-based subdivisions appear to provide complementary information on the spatial organization of anatomical connectivity.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin-fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin- fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy. (c) 2008 Published by Elsevier Inc.
Patric Hagmann - One of the best experts on this subject based on the ideXlab platform.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin-fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin- fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy. (c) 2008 Published by Elsevier Inc.
Jeremy D Schmahmann - One of the best experts on this subject based on the ideXlab platform.
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development of cerebellar connectivity in human fetal brains revealed by high angular resolution diffusion Tractography
NeuroImage, 2014Co-Authors: Emi Takahashi, Jeremy D Schmahmann, Emiko Hayashi, Ellen P GrantAbstract:Abstract High angular resolution diffusion imaging (HARDI) Tractography has provided insights into major white matter pathways and cortical development in the human fetal cerebrum. Our objective in this study was to further apply HARDI tracography to the developing human cerebellum ranging from fetal to adult stages, to outline in broad strokes the 3-dimensional development of white matter and local gray matter organization in the cerebellum. We imaged intact fixed fetal cerebellum specimens at 17 gestational weeks (W), 21W, 31W, 36W, and 38W along with an adult cerebellum for comparison. At the earliest gestational age studied (17W), coherent pathways that formed the superior, middle, and inferior cerebellar peduncles were already detected, but pathways between deep cerebellar nuclei and the cortex were not observed until after 38W. At 36–38W, we identified emerging regional specification of the middle cerebellar peduncle. In the cerebellar cortex, we observed disappearance of radial organization in the sagittal orientation during the studied developmental stages similar to our previous observations in developing cerebral cortex. In contrast, in the axial orientation, cerebellar cortical pathways emerged first sparsely (31W) and then with increased prominence at 36–38W with pathways detected both in the radial and tangential directions to the cortical surface. The cerebellar vermis first contained only pathways tangential to the long axes of folia (17–21W), but pathways parallel to the long axes of folia emerged between 21 and 31W. Our results show the potential for HARDI Tractography to image developing human cerebellar connectivity.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin-fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin- fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy. (c) 2008 Published by Elsevier Inc.
Wen-yih Isaac Tseng - One of the best experts on this subject based on the ideXlab platform.
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Tractography and immunohistochemistry.
2017Co-Authors: Yu-jen Chen, Mu-hui Wang, Ling-ling Chiou, Wen-yih Isaac Tseng, Hsuan-shu LeeAbstract:A: Tractography and immunohistochemistry at 9-wpa. B: Tractography and immunohistochemistry at 10-wpa. The regenerating right upper arms were amputated and embedded for sectioning soon after image acquisition. The white arrowhead in A (Tractography I) indicates a gap between the parental and regenerating triceps brachii. The DTIs at 9-wpa and 10-wpa are similar to those shown in Fig 2. Note that the pathways of the regenerating humeroantebrachialis could not be seen at 9-wpa in Tractography I as triceps brachii could (also see Fig 2). Desmin immunohistochemistry of the whole forelimb in A shows an expected gap (indicated by an open arrow) between the parental and regenerating humeroantebrachialis. In B, the open arrow indicates the filling of the gap in triceps brachii. P = parental muscle part. R = regenerating muscle part. Dash lines indicate amputation planes. Scale bars = 5 mm.
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deterministic diffusion fiber tracking improved by quantitative anisotropy
PLOS ONE, 2013Co-Authors: Fangcheng Yeh, Timothy Verstynen, Yibao Wang, Juan C Fernandezmiranda, Wen-yih Isaac TsengAbstract:Diffusion MRI Tractography has emerged as a useful and popular tool for mapping connections between brain regions. In this study, we examined the performance of quantitative anisotropy (QA) in facilitating deterministic fiber tracking. Two phantom studies were conducted. The first phantom study examined the susceptibility of fractional anisotropy (FA), generalized factional anisotropy (GFA), and QA to various partial volume effects. The second phantom study examined the spatial resolution of the FA-aided, GFA-aided, and QA-aided tractographies. An in vivo study was conducted to track the arcuate fasciculus, and two neurosurgeons blind to the acquisition and analysis settings were invited to identify false tracks. The performance of QA in assisting fiber tracking was compared with FA, GFA, and anatomical information from T1-weighted images. Our first phantom study showed that QA is less sensitive to the partial volume effects of crossing fibers and free water, suggesting that it is a robust index. The second phantom study showed that the QA-aided Tractography has better resolution than the FA-aided and GFA-aided Tractography. Our in vivo study further showed that the QA-aided Tractography outperforms the FA-aided, GFA-aided, and anatomy-aided tractographies. In the shell scheme (HARDI), the FA-aided, GFA-aided, and anatomy-aided tractographies have 30.7%, 32.6%, and 24.45% of the false tracks, respectively, while the QA-aided Tractography has 16.2%. In the grid scheme (DSI), the FA-aided, GFA-aided, and anatomy-aided tractographies have 12.3%, 9.0%, and 10.93% of the false tracks, respectively, while the QA-aided Tractography has 4.43%. The QA-aided deterministic fiber tracking may assist fiber tracking studies and facilitate the advancement of human connectomics.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin-fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy.
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diffusion spectrum magnetic resonance imaging dsi Tractography of crossing fibers
NeuroImage, 2008Co-Authors: Van J Wedeen, Wen-yih Isaac Tseng, Ruopeng Wang, Jeremy D Schmahmann, Thomas Benner, Guangping Dai, Deepak N Pandya, Patric Hagmann, Helen E DarceuilAbstract:MRI Tractography is the mapping of neural fiber pathways based on diffusion MRI of tissue diffusion anisotropy. Tractography based on diffusion tensor imaging (DTI) cannot directly image multiple fiber orientations within a single voxel. To address this limitation, diffusion spectrum MRI (DSI) and related methods were developed to image complex distributions of intravoxel fiber orientation. Here we demonstrate that Tractography based on DSI has the capacity to image crossing fibers in neural tissue. DSI was performed in formalin- fixed brains of adult macaque and in the brains of healthy human subjects. Fiber tract solutions were constructed by a streamline procedure, following directions of maximum diffusion at every point, and analyzed in an interactive visualization environment (TrackVis). We report that DSI Tractography accurately shows the known anatomic fiber crossings in optic chiasm, centrum semiovale, and brainstem; fiber intersections in gray matter, including cerebellar folia and the caudate nucleus; and radial fiber architecture in cerebral cortex. In contrast, none of these examples of fiber crossing and complex structure was identified by DTI analysis of the same data sets. These findings indicate that DSI Tractography is able to image crossing fibers in neural tissue, an essential step toward non-invasive imaging of connectional neuroanatomy. (c) 2008 Published by Elsevier Inc.
Francesca Granata - One of the best experts on this subject based on the ideXlab platform.
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optic radiations evaluation in patients affected by high grade gliomas a side by side constrained spherical deconvolution and diffusion tensor imaging study
Neuroradiology, 2016Co-Authors: Enricomaria Mormina, Concetta Alafaci, Francesco Tomasello, Sergio Vinci, Alessandro Arrigo, Alessandro Calamuneri, Silvia Marino, Rosa Morabito, M Longo, Francesca GranataAbstract:Introduction The need to improve surgical efficacy in patients affected by high-grade gliomas has led to development of advanced pre-surgical MRI-based techniques such as Tractography. This study investigates pre-surgical planning of optic radiations (ORs) in patients affected by occipito-temporo-parietal high-grade gliomas, by means of constrained spherical deconvolution (CSD) and diffusion tensor imaging (DTI) Tractography.
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MRI Tractography of Corticospinal Tract and Arcuate Fasciculus in High-Grade Gliomas Performed by Constrained Spherical Deconvolution: Qualitative and Quantitative Analysis
American Journal of Neuroradiology, 2015Co-Authors: Enricomaria Mormina, Concetta Alafaci, Francesco Tomasello, Sergio Vinci, Alessandro Arrigo, Michele Gaeta, Marcello Longo, Alessandro Calamuneri, Silvia Marino, Francesca GranataAbstract:BACKGROUND AND PURPOSE: MR imaging Tractography is increasingly used to perform noninvasive presurgical planning for brain gliomas. Recently, constrained spherical deconvolution Tractography was shown to overcome several limitations of commonly used DTI Tractography. The purpose of our study was to evaluate WM tract alterations of both the corticospinal tract and arcuate fasciculus in patients with high-grade gliomas, through qualitative and quantitative analysis of probabilistic constrained spherical deconvolution Tractography, to perform reliable presurgical planning. MATERIALS AND METHODS: Twenty patients with frontoparietal high-grade gliomas were recruited and evaluated by using a 3T MR imaging scanner with both morphologic and diffusion sequences (60 diffusion directions). We performed probabilistic constrained spherical deconvolution Tractography and tract quantification following diffusion tensor parameters: fractional anisotropy; mean diffusivity; linear, planar, and spherical coefficients. RESULTS: In all patients, we obtained tractographic reconstructions of the medial and lateral portions of the corticospinal tract and arcuate fasciculus, both on the glioma-affected and nonaffected sides of the brain. The affected lateral corticospinal tract and the arcuate fasciculus showed decreased fractional anisotropy ( z = 2.51, n = 20, P = .006; z = 2.52, n = 20, P = .006) and linear coefficient ( z = 2.51, n = 20, P = .006; z = 2.52, n = 20, P = .006) along with increased spherical coefficient ( z = −2.51, n = 20, P = .006; z = −2.52, n = 20, P = .006). Mean diffusivity values were increased only in the lateral corticospinal tract ( z = −2.53, n = 20, P = .006). CONCLUSIONS: In this study, we demonstrated that probabilistic constrained spherical deconvolution can provide essential qualitative and quantitative information in presurgical planning, which was not otherwise achievable with DTI. These findings can have important implications for the surgical approach and postoperative outcome in patients with glioma.
