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Sample records for diffusion tensor fiber

  1. Deep Into the Fibers! Postmortem Diffusion Tensor Imaging in Forensic Radiology.

    Science.gov (United States)

    Flach, Patricia Mildred; Schroth, Sarah; Schweitzer, Wolf; Ampanozi, Garyfalia; Slotboom, Johannes; Kiefer, Claus; Germerott, Tanja; Thali, Michael J; El-Koussy, Marwan

    2015-09-01

    In traumatic brain injury, diffusion-weighted and diffusion tensor imaging of the brain are essential techniques for determining the pathology sustained and the outcome. Postmortem cross-sectional imaging is an established adjunct to forensic autopsy in death investigation. The purpose of this prospective study was to evaluate postmortem diffusion tensor imaging in forensics for its feasibility, influencing factors and correlation to the cause of death compared with autopsy. Postmortem computed tomography, magnetic resonance imaging, and diffusion tensor imaging with fiber tracking were performed in 10 deceased subjects. The Likert scale grading of colored fractional anisotropy maps was correlated to the body temperature and intracranial pathology to assess the diagnostic feasibility of postmortem diffusion tensor imaging and fiber tracking. Optimal fiber tracking (>15,000 fiber tracts) was achieved with a body temperature at 10°C. Likert scale grading showed no linear correlation (P > 0.7) to fiber tract counts. No statistically significant correlation between total fiber count and postmortem interval could be observed (P = 0.122). Postmortem diffusion tensor imaging and fiber tracking allowed for radiological diagnosis in cases with shearing injuries but was impaired in cases with pneumencephalon and intracerebral mass hemorrhage. Postmortem diffusion tensor imaging with fiber tracking provides an exceptional in situ insight "deep into the fibers" of the brain with diagnostic benefit in traumatic brain injury and axonal injuries in the assessment of the underlying cause of death, considering influencing factors for optimal imaging technique.

  2. Diffusion tensor imaging of the nigrostriatal fibers in Parkinson's disease.

    Science.gov (United States)

    Zhang, Yu; Wu, I-Wei; Buckley, Shannon; Coffey, Christopher S; Foster, Eric; Mendick, Susan; Seibyl, John; Schuff, Norbert

    2015-08-01

    Parkinson's disease (PD) is histopathologically characterized by the loss of dopamine neurons in the substantia nigra pars compacta. The depletion of these neurons is thought to reduce the dopaminergic function of the nigrostriatal pathway, as well as the neural fibers that link the substantia nigra to the striatum (putamen and caudate), causing a dysregulation in striatal activity that ultimately leads to lack of movement control. Based on diffusion tensor imaging, visualizing this pathway and measuring alterations of the fiber integrity remain challenging. The objectives were to 1) develop a diffusion tensor tractography protocol for reliably tracking the nigrostriatal fibers on multicenter data; 2) test whether the integrities measured by diffusion tensor imaging of the nigrostriatal fibers are abnormal in PD; and 3) test whether abnormal integrities of the nigrostriatal fibers in PD patients are associated with the severity of motor disability and putaminal dopamine binding ratios. Diffusion tensor tractography was performed on 50 drug-naïve PD patients and 27 healthy control subjects from the international multicenter Parkinson's Progression Marker Initiative. Tractography consistently detected the nigrostriatal fibers, yielding reliable diffusion measures. Fractional anisotropy, along with radial and axial diffusivity of the nigrostriatal tract, showed systematic abnormalities in patients. In addition, variations in fractional anisotropy and radial diffusivity of the nigrostriatal tract were associated with the degree of motor deficits in PD patients. Taken together, the findings imply that the diffusion tensor imaging characteristic of the nigrostriatal tract is potentially an index for detecting and staging of early PD. © 2015 International Parkinson and Movement Disorder Society.

  3. Comparison of Magnetic Susceptibility Tensor and Diffusion Tensor of the Brain.

    Science.gov (United States)

    Li, Wei; Liu, Chunlei

    2013-10-01

    Susceptibility tensor imaging (STI) provides a novel approach for noninvasive assessment of the white matter pathways of the brain. Using mouse brain ex vivo , we compared STI with diffusion tensor imaging (DTI), in terms of tensor values, principal tensor values, anisotropy values, and tensor orientations. Despite the completely different biophysical underpinnings, magnetic susceptibility tensors and diffusion tensors show many similarities in the tensor and principal tensor images, for example, the tensors perpendicular to the fiber direction have the highest gray-white matter contrast, and the largest principal tensor is along the fiber direction. Comparison to DTI fractional anisotropy, the susceptibility anisotropy provides much higher sensitivity to the chemical composition of the white matter, especially myelin. The high sensitivity can be further enhanced with the perfusion of ProHance, a gadolinium-based contrast agent. Regarding the tensor orientations, the direction of the largest principal susceptibility tensor agrees with that of diffusion tensors in major white matter fiber bundles. The STI fiber tractography can reconstruct the fiber pathways for the whole corpus callosum and for white matter fiber bundles that are in close contact but in different orientations. There are some differences between susceptibility and diffusion tensor orientations, which are likely due to the limitations in the current STI reconstruction. With the development of more accurate reconstruction methods, STI holds the promise for probing the white matter micro-architectures with more anatomical details and higher chemical sensitivity.

  4. Diffusion tensor MRI and fiber tractography of the sacral plexus in children with spina bifida

    DEFF Research Database (Denmark)

    Haakma, Wieke; Dik, Pieter; ten Haken, Bennie

    2014-01-01

    anatomical and microstructural properties of the sacral plexus of patients with spina bifida using diffusion tensor imaging and fiber tractography. MATERIALS AND METHODS: Ten patients 8 to 16 years old with spina bifida underwent diffusion tensor imaging on a 3 Tesla magnetic resonance imaging system...... diffusivity values at S1-S3 were significantly lower in patients. CONCLUSIONS: To our knowledge this 3 Tesla magnetic resonance imaging study showed for the first time sacral plexus asymmetry and disorganization in 10 patients with spina bifida using diffusion tensor imaging and fiber tractography...

  5. Comparing a diffusion tensor and non-tensor approach to white matter fiber tractography in chronic stroke.

    Science.gov (United States)

    Auriat, A M; Borich, M R; Snow, N J; Wadden, K P; Boyd, L A

    2015-01-01

    Diffusion tensor imaging (DTI)-based tractography has been used to demonstrate functionally relevant differences in white matter pathway status after stroke. However, it is now known that the tensor model is insensitive to the complex fiber architectures found in the vast majority of voxels in the human brain. The inability to resolve intra-voxel fiber orientations may have important implications for the utility of standard DTI-based tract reconstruction methods. Intra-voxel fiber orientations can now be identified using novel, tensor-free approaches. Constrained spherical deconvolution (CSD) is one approach to characterize intra-voxel diffusion behavior. In the current study, we performed DTI- and CSD-based tract reconstruction of the corticospinal tract (CST) and corpus callosum (CC) to test the hypothesis that characterization of complex fiber orientations may improve the robustness of fiber tract reconstruction and increase the sensitivity to identify functionally relevant white matter abnormalities in individuals with chronic stroke. Diffusion weighted magnetic resonance imaging was performed in 27 chronic post-stroke participants and 12 healthy controls. Transcallosal pathways and the CST bilaterally were reconstructed using DTI- and CSD-based tractography. Mean fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD) were calculated across the tracts of interest. The total number and volume of reconstructed tracts was also determined. Diffusion measures were compared between groups (Stroke, Control) and methods (CSD, DTI). The relationship between post-stroke motor behavior and diffusion measures was evaluated. Overall, CSD methods identified more tracts than the DTI-based approach for both CC and CST pathways. Mean FA, ADC, and RD differed between DTI and CSD for CC-mediated tracts. In these tracts, we discovered a difference in FA for the CC between stroke and healthy control groups using CSD but

  6. Comparing a diffusion tensor and non-tensor approach to white matter fiber tractography in chronic stroke

    Directory of Open Access Journals (Sweden)

    A.M. Auriat

    2015-01-01

    Full Text Available Diffusion tensor imaging (DTI-based tractography has been used to demonstrate functionally relevant differences in white matter pathway status after stroke. However, it is now known that the tensor model is insensitive to the complex fiber architectures found in the vast majority of voxels in the human brain. The inability to resolve intra-voxel fiber orientations may have important implications for the utility of standard DTI-based tract reconstruction methods. Intra-voxel fiber orientations can now be identified using novel, tensor-free approaches. Constrained spherical deconvolution (CSD is one approach to characterize intra-voxel diffusion behavior. In the current study, we performed DTI- and CSD-based tract reconstruction of the corticospinal tract (CST and corpus callosum (CC to test the hypothesis that characterization of complex fiber orientations may improve the robustness of fiber tract reconstruction and increase the sensitivity to identify functionally relevant white matter abnormalities in individuals with chronic stroke. Diffusion weighted magnetic resonance imaging was performed in 27 chronic post-stroke participants and 12 healthy controls. Transcallosal pathways and the CST bilaterally were reconstructed using DTI- and CSD-based tractography. Mean fractional anisotropy (FA, apparent diffusion coefficient (ADC, axial diffusivity (AD, and radial diffusivity (RD were calculated across the tracts of interest. The total number and volume of reconstructed tracts was also determined. Diffusion measures were compared between groups (Stroke, Control and methods (CSD, DTI. The relationship between post-stroke motor behavior and diffusion measures was evaluated. Overall, CSD methods identified more tracts than the DTI-based approach for both CC and CST pathways. Mean FA, ADC, and RD differed between DTI and CSD for CC-mediated tracts. In these tracts, we discovered a difference in FA for the CC between stroke and healthy control groups

  7. Fiber crossing in human brain depicted with diffusion tensor MR imaging

    DEFF Research Database (Denmark)

    Wiegell, M.R.; Larsson, H.B.; Wedeen, V.J.

    2000-01-01

    Human white matter fiber crossings were investigated with use of the full eigenstructure of the magnetic resonance diffusion tensor. Intravoxel fiber dispersions were characterized by the plane spanned by the major and medium eigenvectors and depicted with three-dimensional graphics. This method...

  8. Diffusion tensor magnetic resonance imaging and fiber tractography of the sacral plexus in children with spina bifida

    DEFF Research Database (Denmark)

    Haakma, Wieke; Dik, Pieter; ten Haken, Bennie

    2014-01-01

    anatomical and microstructural properties of the sacral plexus of patients with spina bifida using diffusion tensor imaging and fiber tractography. MATERIALS AND METHODS: Ten patients 8 to 16 years old with spina bifida underwent diffusion tensor imaging on a 3 Tesla magnetic resonance imaging system...... diffusivity values at S1-S3 were significantly lower in patients. CONCLUSIONS: To our knowledge this 3 Tesla magnetic resonance imaging study showed for the first time sacral plexus asymmetry and disorganization in 10 patients with spina bifida using diffusion tensor imaging and fiber tractography...

  9. Quantitative diffusion tensor deterministic and probabilistic fiber tractography in relapsing-remitting multiple sclerosis

    International Nuclear Information System (INIS)

    Hu Bing; Ye Binbin; Yang Yang; Zhu Kangshun; Kang Zhuang; Kuang Sichi; Luo Lin; Shan Hong

    2011-01-01

    Purpose: Our aim was to study the quantitative fiber tractography variations and patterns in patients with relapsing-remitting multiple sclerosis (RRMS) and to assess the correlation between quantitative fiber tractography and Expanded Disability Status Scale (EDSS). Material and methods: Twenty-eight patients with RRMS and 28 age-matched healthy volunteers underwent a diffusion tensor MR imaging study. Quantitative deterministic and probabilistic fiber tractography were generated in all subjects. And mean numbers of tracked lines and fiber density were counted. Paired-samples t tests were used to compare tracked lines and fiber density in RRMS patients with those in controls. Bivariate linear regression model was used to determine the relationship between quantitative fiber tractography and EDSS in RRMS. Results: Both deterministic and probabilistic tractography's tracked lines and fiber density in RRMS patients were less than those in controls (P < .001). Both deterministic and probabilistic tractography's tracked lines and fiber density were found negative correlations with EDSS in RRMS (P < .001). The fiber tract disruptions and reductions in RRMS were directly visualized on fiber tractography. Conclusion: Changes of white matter tracts can be detected by quantitative diffusion tensor fiber tractography, and correlate with clinical impairment in RRMS.

  10. Spatial Mapping of Translational Diffusion Coefficients Using Diffusion Tensor Imaging: A Mathematical Description.

    Science.gov (United States)

    Shetty, Anil N; Chiang, Sharon; Maletic-Savatic, Mirjana; Kasprian, Gregor; Vannucci, Marina; Lee, Wesley

    2014-01-01

    In this article, we discuss the theoretical background for diffusion weighted imaging and diffusion tensor imaging. Molecular diffusion is a random process involving thermal Brownian motion. In biological tissues, the underlying microstructures restrict the diffusion of water molecules, making diffusion directionally dependent. Water diffusion in tissue is mathematically characterized by the diffusion tensor, the elements of which contain information about the magnitude and direction of diffusion and is a function of the coordinate system. Thus, it is possible to generate contrast in tissue based primarily on diffusion effects. Expressing diffusion in terms of the measured diffusion coefficient (eigenvalue) in any one direction can lead to errors. Nowhere is this more evident than in white matter, due to the preferential orientation of myelin fibers. The directional dependency is removed by diagonalization of the diffusion tensor, which then yields a set of three eigenvalues and eigenvectors, representing the magnitude and direction of the three orthogonal axes of the diffusion ellipsoid, respectively. For example, the eigenvalue corresponding to the eigenvector along the long axis of the fiber corresponds qualitatively to diffusion with least restriction. Determination of the principal values of the diffusion tensor and various anisotropic indices provides structural information. We review the use of diffusion measurements using the modified Stejskal-Tanner diffusion equation. The anisotropy is analyzed by decomposing the diffusion tensor based on symmetrical properties describing the geometry of diffusion tensor. We further describe diffusion tensor properties in visualizing fiber tract organization of the human brain.

  11. Seamless warping of diffusion tensor fields

    DEFF Research Database (Denmark)

    Xu, Dongrong; Hao, Xuejun; Bansal, Ravi

    2008-01-01

    To warp diffusion tensor fields accurately, tensors must be reoriented in the space to which the tensors are warped based on both the local deformation field and the orientation of the underlying fibers in the original image. Existing algorithms for warping tensors typically use forward mapping...... of seams, including voxels in which the deformation is extensive. Backward mapping, however, cannot reorient tensors in the template space because information about the directional orientation of fiber tracts is contained in the original, unwarped imaging space only, and backward mapping alone cannot...... transfer that information to the template space. To combine the advantages of forward and backward mapping, we propose a novel method for the spatial normalization of diffusion tensor (DT) fields that uses a bijection (a bidirectional mapping with one-to-one correspondences between image spaces) to warp DT...

  12. Diffusion tensor tractography of language functional areas and fiber pathways in normal human brain

    International Nuclear Information System (INIS)

    Sun Xuejin; Dai Jianping; Chen Hongyan; Gao Peiyi; Ai Lin; Tian Shengyong; Pang Ruilin

    2007-01-01

    Objective: To demonstrate the fiber pathways of Broca area to the other functional brain areas with diffusion tensor imaging and fiber tracking. Methods: Conventionality MRI, diffusion tensor imaging (DTI) and fiber tracking were performed using 3.0 T MRI in 20 healthy person. The fiber bundles and tracts were analyzed in Broca area and contralateral normal area. Results: The left-side fiber bundles were 428 and the right-side were 416 in B45 area, there were no statistically significant differences between both sides (t=0.216, P>0.05). The left-side fiber bundles were 432 and the right-side were 344 in B44 area,there were statistically significant (t=2.314, P 0.05). Differences of the arcuate fascicule between both sides were not statistically significant (t=-0.465, P>0.05), the mean FA on the left was higher than the right (t=1.912, P<0.05). DTI and fiber tracking exhibited that the fiber bundles from Broca area were distributed superoanteriorly to the lateral foreside of the frontal lobe, lateroinferiorly to the occipital lobe through external capsule, and went down through globus pallidus and internal capsule. Conclusion: The fiber tracts bewteen Broca area and other brain areas were the fundamental structures for performing language function of the human brain. (authors)

  13. Probing white-matter microstructure with higher-order diffusion tensors and susceptibility tensor MRI

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    Liu, Chunlei; Murphy, Nicole E.; Li, Wei

    2012-01-01

    Diffusion MRI has become an invaluable tool for studying white matter microstructure and brain connectivity. The emergence of quantitative susceptibility mapping and susceptibility tensor imaging (STI) has provided another unique tool for assessing the structure of white matter. In the highly ordered white matter structure, diffusion MRI measures hindered water mobility induced by various tissue and cell membranes, while susceptibility sensitizes to the molecular composition and axonal arrangement. Integrating these two methods may produce new insights into the complex physiology of white matter. In this study, we investigated the relationship between diffusion and magnetic susceptibility in the white matter. Experiments were conducted on phantoms and human brains in vivo. Diffusion properties were quantified with the diffusion tensor model and also with the higher order tensor model based on the cumulant expansion. Frequency shift and susceptibility tensor were measured with quantitative susceptibility mapping and susceptibility tensor imaging. These diffusion and susceptibility quantities were compared and correlated in regions of single fiber bundles and regions of multiple fiber orientations. Relationships were established with similarities and differences identified. It is believed that diffusion MRI and susceptibility MRI provide complementary information of the microstructure of white matter. Together, they allow a more complete assessment of healthy and diseased brains. PMID:23507987

  14. Diffusion tensor imaging of the human skeletal muscle: contributions and applications

    International Nuclear Information System (INIS)

    Neji, Radhouene

    2010-01-01

    In this thesis, we present several techniques for the processing of diffusion tensor images. They span a wide range of tasks such as estimation and regularization, clustering and segmentation, as well as registration. The variational framework proposed for recovering a tensor field from noisy diffusion weighted images exploits the fact that diffusion data represent populations of fibers and therefore each tensor can be reconstructed using a weighted combination of tensors lying in its neighborhood. The segmentation approach operates both at the voxel and the fiber tract levels. It is based on the use of Mercer kernels over Gaussian diffusion probabilities to model tensor similarity and spatial interactions, allowing the definition of fiber metrics that combine information from spatial localization and diffusion tensors. Several clustering techniques can be subsequently used to segment tensor fields and fiber tractographies. Moreover, we show how to develop supervised extensions of these algorithms. The registration algorithm uses probability kernels in order to match moving and target images. The deformation consistency is assessed using the distortion induced in the distances between neighboring probabilities. Discrete optimization is used to seek an optimum of the defined objective function. The experimental validation is done over a dataset of manually segmented diffusion images of the lower leg muscle for healthy and diseased subjects. The results of the techniques developed throughout this thesis are promising. (author)

  15. Diffusion tensor imaging in inflammatory and neoplastic intramedullary spinal cord lesions: Focusing on fiber tracking

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    Kim, Hyo Jin; Lee, Joon Woo; Lee, Eugene; Kim, Sung Gon; Kang, Yu Suhn; Ahn, Joong Mo; Kang, Heung Sik [Dept. of Radiology, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of)

    2017-02-15

    Inflammatory and neoplastic intramedullary spinal cord lesions have overlapping clinical features, and it is occasionally difficult to distinguish one from the other on conventional magnetic resonance imaging. We aimed to compare diffusion tensor imaging findings between inflammatory and neoplastic intramedullary spinal cord lesions, with a specific focus on patterns of fiber tracking. Diffusion tensor imaging was performed in patients with either inflammatory or neoplastic intramedullary spinal cord lesions. The fiber tracking patterns (categorized as “intact,” “displaced,” or “interrupted”) were compared between these two groups. Eight patients were included in the study: 5 patients with pathologically or clinically confirmed inflammatory lesions and 3 patients with pathologically or clinically confirmed neoplastic lesions. Among the 5 patients with inflammatory lesions, 2 patients exhibited the displaced pattern and 3 patients exhibited the intact pattern. Among the 3 patients with neoplastic lesions, 1 patient exhibited the intact pattern, 1 patient exhibited the displaced pattern, and 1 patient exhibited the interrupted pattern. In this study, inflammatory and neoplastic intramedullary spinal cord lesions were not clearly differentiated by fiber tracking; both conditions can present with overlapping features such as displaced fibers. The exclusion of inflammatory conditions based on the presence of displaced fibers in fiber tracking images should be avoided.

  16. Effect of increasing diffusion gradient direction number on diffusion tensor imaging fiber tracking in the human brain

    International Nuclear Information System (INIS)

    Yao, Xu Fang; Liang, Bie Bei; Xia, Tian; Huang, Qin Ming; Zhuang, Song Lin; Yu, Tong Gang

    2015-01-01

    To assess the effects of varying the number of diffusion gradient directions (NDGDs) on diffusion tensor fiber tracking (FT) in human brain white matter using tract characteristics. Twelve normal volunteers underwent diffusion tensor imaging (DTI) scanning with NDGDs of 6, 11, 15, 21, and 31 orientations. Three fiber tract groups, including the splenium of the corpus callosum (CC), the entire CC, and the full brain tract, were reconstructed by deterministic DTI-FT. Tract architecture was first qualitatively evaluated by visual observation. Six quantitative tract characteristics, including the number of fibers (NF), average length (AL), fractional anisotropy (FA), relative anisotropy (RA), mean diffusivity (MD), and volume ratio (VR) were measured for the splenium of the CC at the tract branch level, for the entire CC at tract level, and for the full brain tract at the whole brain level. Visual results and those of NF, AL, FA, RA, MD, and VR were compared among the five different NDGDs. The DTI-FT with NDGD of 11, 15, 21, and 31 orientations gave better tracking results compared with NDGD of 6 after the visual evaluation. NF, FA, RA, MD, and VR values with NDGD of six were significantly greater (smallest p = 0.001 to largest p = 0.042) than those with four other NDGDs (11, 15, 21, or 31 orientations), whereas AL measured with NDGD of six was significantly smaller (smallest p = 0.001 to largest p = 0.041) than with four other NDGDs (11, 15, 21, or 31 orientations). No significant differences were observed in the results among the four NDGD groups of 11, 15, 21, and 31 directions (smallest p = 0.059 to largest p = 1.000). The main fiber tracts were detected with NDGD of six orientations; however, the use of larger NDGD (> or = 11 orientations) could provide improved tract characteristics at the expense of longer scanning time.

  17. Effect of increasing diffusion gradient direction number on diffusion tensor imaging fiber tracking in the human brain

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Xu Fang; Liang, Bie Bei; Xia, Tian; Huang, Qin Ming; Zhuang, Song Lin [School of Optical-Electrical and Computer Engineering, Shanghai Medical Instrument College, University of Shanghai for Science and Technology, Shanghai (China); Yu, Tong Gang [Dept. of Radiology, Huashan Hospital, Fudan University, Shanghai (China)

    2015-04-15

    To assess the effects of varying the number of diffusion gradient directions (NDGDs) on diffusion tensor fiber tracking (FT) in human brain white matter using tract characteristics. Twelve normal volunteers underwent diffusion tensor imaging (DTI) scanning with NDGDs of 6, 11, 15, 21, and 31 orientations. Three fiber tract groups, including the splenium of the corpus callosum (CC), the entire CC, and the full brain tract, were reconstructed by deterministic DTI-FT. Tract architecture was first qualitatively evaluated by visual observation. Six quantitative tract characteristics, including the number of fibers (NF), average length (AL), fractional anisotropy (FA), relative anisotropy (RA), mean diffusivity (MD), and volume ratio (VR) were measured for the splenium of the CC at the tract branch level, for the entire CC at tract level, and for the full brain tract at the whole brain level. Visual results and those of NF, AL, FA, RA, MD, and VR were compared among the five different NDGDs. The DTI-FT with NDGD of 11, 15, 21, and 31 orientations gave better tracking results compared with NDGD of 6 after the visual evaluation. NF, FA, RA, MD, and VR values with NDGD of six were significantly greater (smallest p = 0.001 to largest p = 0.042) than those with four other NDGDs (11, 15, 21, or 31 orientations), whereas AL measured with NDGD of six was significantly smaller (smallest p = 0.001 to largest p = 0.041) than with four other NDGDs (11, 15, 21, or 31 orientations). No significant differences were observed in the results among the four NDGD groups of 11, 15, 21, and 31 directions (smallest p = 0.059 to largest p = 1.000). The main fiber tracts were detected with NDGD of six orientations; however, the use of larger NDGD (> or = 11 orientations) could provide improved tract characteristics at the expense of longer scanning time.

  18. Age-related differences in diffusion tensor indices and fiber architecture in the medial and lateral gastrocnemius.

    Science.gov (United States)

    Sinha, Usha; Csapo, Robert; Malis, Vadim; Xue, Yanjie; Sinha, Shantanu

    2015-04-01

    To investigate age related changes in diffusion tensor indices and fiber architecture of the medial and lateral gastrocnemius (MG and LG) muscles using diffusion tensor imaging (DTI). The lower leg of five young and five senior subjects was scanned at 3 Tesla and DTI indices extracted using three methods: region of interest, histogram, and tract based. Tracked fibers were automatically edited to ensure physiologically relevant tracks. Pennation angles were measured with respect to the deep and superficial aponeuroses of both muscles. The three methods provided internally consistent measures of the DTI indices (correlation coefficient in the range of 0.90-0.99). The primary, secondary, and tertiary eigenvalues in the MG and LG increased significantly in the senior cohort (P < 0.05), while the small increase in fractional anisotropy with age was not significant (MG/LG: P = 0.39/0.85; 95% confidence interval: [-0.059/-0.056, 0.116/0.064]). Fiber lengths of MG fibers originating distally were significantly decreased in seniors (P < 0.05) while pennation angles decreased with age in the MG and LG but this was not significant. Fiber atrophy and increased fibrosis have opposing effects on the diffusion indices resulting in a complicated dependence with aging. Fiber architectural changes could play a role in determining aging muscle function. © 2014 Wiley Periodicals, Inc.

  19. Age Related Differences in Diffusion Tensor Indices and Fiber Architecture in the Medial and Lateral Gastrocnemius

    Science.gov (United States)

    Sinha, Usha; Csapo, Robert; Malis, Vadim; Xue, Yanjie; Sinha, Shantanu

    2014-01-01

    Purpose To investigate age related changes in diffusion tensor indices and fiber architecture of the medial and lateral gastrocnemius (MG and LG) muscles using diffusion tensor imaging (DTI). Materials and Methods The lower leg of five young and five senior subjects was scanned at 3T and DTI indices extracted using three methods: ROI, histogram and tract based. Tracked fibers were automatically edited to ensure physiologically relevant tracks. Pennation angles were measured with respect to the deep and superficial aponeuroses of both muscles. Results The three methods provided internally consistent measures of the DTI indices (correlation coefficient in the range of 0.90-0.99). The primary, secondary and tertiary eigenvalues in the MG and LG increased significantly in the senior cohort (p<0.05), while the small increase in fractional anisotropy (FA) with age was not significant (MG/LG: p=0.39/0.85; 95% CI:[ −0.059/-0.056, 0.116/0.064]). Fiber lengths of MG fibers originating distally were significantly decreased in seniors (p<0.05) while pennation angles decreased with age in the MG and LG but this was not significant. Conclusion Fiber atrophy and increased fibrosis have opposing effects on the diffusion indices resulting in a complicated dependence with aging. Fiber architectural changes could play a role in determining aging muscle function. PMID:24771672

  20. Imaging of postthalamic visual fiber tracts by anisotropic diffusion weighted MRI and diffusion tensor imaging: principles and applications

    International Nuclear Information System (INIS)

    Reinges, Marcus H.T.; Schoth, Felix; Coenen, Volker A.; Krings, Timo

    2004-01-01

    Diffusion weighted MRI offers the possibility to study the course of the cerebral white matter tracts. In the present manuscript, the basics, the technique and the limitations of diffusion tensor imaging and anisotropic diffusion weighted MRI are presented and their applications in various neurological and neurosurgical diseases are discussed with special emphasis on the visual system. A special focus is laid on the combination of fiber tract imaging, anatomical imaging and functional MRI for presurgical planning and intraoperative neuronavigation of lesions near the visual system

  1. Quantitative diffusion tensor fiber tracking of age-related changes in the limbic system

    International Nuclear Information System (INIS)

    Stadlbauer, Andreas; Salomonowitz, Erich; Strunk, Guido; Hammen, Thilo; Ganslandt, Oliver

    2008-01-01

    Cerebral white matter is known to undergo degradation with aging, and diffusion tensor imaging (DTI) is capable of revealing the white matter integrity. We assessed age-related changes of quantitative diffusivity parameters and fiber characteristics within the fornix and the cingulum. Thirty-eight healthy subjects aged 18-88 years were examined at 3 Tesla using a 1.9-mm isotropic DTI sequence. Quantitative fiber tracking was performed for 3D-segmentation of the fornix and the cingulum to determine fractional anisotropy (FA), mean diffusivity (MD), eigenvalues (λ 1 , λ 2 , and λ 3 ), number of fibers (NoF), and mean NoF/voxel (FpV). In the fornix, all diffusivity parameters (FA, MD, and eigenvalues) were moderately correlated with age. Strong and moderate negative correlations for NoF and FpV were found, respectively. In the cingulum, no correlation was observed between FA and age, and only weak correlations for the other quantitative parameters. Differences in correlations between the fornix and the cingulum were significant for all diffusivity parameters and for NoF, but not for FpV. The strongest relative changes per decade of age were found in the fornix: FA -2.1%, MD 4.2%, NoF -10.6%, and FpV -4.6%. Our quantitative 3D fiber tracking approach shows that the cingulum is resistant to aging while the fornix is not. (orig.)

  2. The value of 3 T MR diffusion tensor fiber tractography study of association fasciculus of normative human in vivo primarily

    International Nuclear Information System (INIS)

    Sun Xuejin; Dai Jianping; Gao Peiyi; Li Shaowu; Ai Lin; Chen Hongyan; Tian Shengyong; Pang Ruilin

    2006-01-01

    Objective: To exhibit the fibers of association fascicules, aims at demonstrating the association fibers of brain with diffusion tensor fiber tracking technique. Methods: Conventionality MRI, diffusion tensor imaging (DTI) and diffusion tensor fiber tractography (DT-FT) were performed in twenty healthy subjects, including eighteen right-handed (sixteen men and four women) and two left-handed (one male and one female) by 3 T Siemens Trio 2003 T MRI. To select arcuate fascicules, inferior longitudinal fascicules, frontalwoceipital fascicules, corpus callosum, posterior limb of internal capsule and external capsule as seeds used to track fibers. Results: Diffusion tensor fiber tracking exhibited bundles of external capsule left mean fibers were 308 bundles, right fibers were 307 bundles (t=0.138, P>0.05), frontal-occipital tracks left mean fibers were 115 bundles, right fibers were 110 bundles(t=1.174, P>0.05), and their fractional anisotropy (FA) valueexternal capsule mean FA left was 0.361, the right was 0.362 (t=-0.184, P>0.05). Frontal-occipital tracks mean fractional anisotropy left was 0.352, the right was 0.351 (t=-0.816, P>0.05). The difference between both sides were statistically insignificant (P>0.05). The posterior limb of internal capsule left mean fibers were 249 bundles, right fibers were 257 bundles (t=-0.818, P>0.05), arcuate fascietfiesleft mean fibers were 198 bundles, right fibers were 204 bundles (t=-0.465, P>0.05 ) fibers difference between both sides were statistically insignificant (P>0.05), but the individual difference was significant, and their fractional anisotropy difference between both sides (posterior limb of internal capsule mean FA left was 0.450, the right was 0.444 (t=2.771, P 0.05). Mean FA left was 0.369, the right was 0.370(t=-0.178, P>0.05) ,difference between both sides was statistically insignificant (P>0.05). But the individual difference was significant. Some of them were the left larger than the right side. The frontal

  3. Diffusion Tensor Imaging-Based Research on Human White Matter Anatomy

    Directory of Open Access Journals (Sweden)

    Ming-guo Qiu

    2012-01-01

    Full Text Available The aim of this study is to investigate the white matter by the diffusion tensor imaging and the Chinese visible human dataset and to provide the 3D anatomical data of the corticospinal tract for the neurosurgical planning by studying the probabilistic maps and the reproducibility of the corticospinal tract. Diffusion tensor images and high-resolution T1-weighted images of 15 healthy volunteers were acquired; the DTI data were processed using DtiStudio and FSL software. The FA and color FA maps were compared with the sectional images of the Chinese visible human dataset. The probability maps of the corticospinal tract were generated as a quantitative measure of reproducibility for each voxel of the stereotaxic space. The fibers displayed by the diffusion tensor imaging were well consistent with the sectional images of the Chinese visible human dataset and the existing anatomical knowledge. The three-dimensional architecture of the white matter fibers could be clearly visualized on the diffusion tensor tractography. The diffusion tensor tractography can establish the 3D probability maps of the corticospinal tract, in which the degree of intersubject reproducibility of the corticospinal tract is consistent with the previous architectonic report. DTI is a reliable method of studying the fiber connectivity in human brain, but it is difficult to identify the tiny fibers. The probability maps are useful for evaluating and identifying the corticospinal tract in the DTI, providing anatomical information for the preoperative planning and improving the accuracy of surgical risk assessments preoperatively.

  4. Diffusion tensor imaging for nerve fiber bundles in the brain stem and spinocerebellar degeneration

    International Nuclear Information System (INIS)

    Honma, Tsuguo

    2009-01-01

    Diffusion tensor imaging (DTI) can create an image of the anisotropic nature of diffusion and express it quantitatively. Nerve fibers have a large anisotropic diffusion, and it is possible to obtain images of the nerve fiber bundle. The purpose of this study is to observe the nerve fiber bundles in the brain stem using DTI and study its potential for diagnosing the type of spinocerebellar degeneration (SCD). Fractional anisotropy (FA) maps and 3D-tractography images were obtained for 41 subjects with no brain stem abnormalities. We created an apparent diffusion coefficient (ADC) map and an FA map using DTI for 16 subjects in the disease group (11 with hereditary SCD and 5 with non-hereditary SCD) and 25 in the control group. The diffusion value of the pons and middle cerebellar peduncle was measured using ADC, and the degree of anisotropic diffusion was measured using FA. The pyramidal tract, superior cerebellar peduncle, and inferior cerebellar peduncle were clearly demonstrated for all cases. ADC for the middle cerebellar peduncle in spinocerebellar ataxin (SCA)1 was significantly higher, similar to that for the pons in dentatorubro-pallidoluysian atrophy (DRPLA). In MSA-C, ADC for both the pons and middle cerebellar peduncle was significantly elevated and FA was significantly decreased. There were no significant changes in SCA3. We could observe the nerve fiber bundles in the brain stem using DTI. FA and ADC measurements with DTI can aid in diagnosing the type of SCD. (author)

  5. Time-optimized high-resolution readout-segmented diffusion tensor imaging.

    Directory of Open Access Journals (Sweden)

    Gernot Reishofer

    Full Text Available Readout-segmented echo planar imaging with 2D navigator-based reacquisition is an uprising technique enabling the sampling of high-resolution diffusion images with reduced susceptibility artifacts. However, low signal from the small voxels and long scan times hamper the clinical applicability. Therefore, we introduce a regularization algorithm based on total variation that is applied directly on the entire diffusion tensor. The spatially varying regularization parameter is determined automatically dependent on spatial variations in signal-to-noise ratio thus, avoiding over- or under-regularization. Information about the noise distribution in the diffusion tensor is extracted from the diffusion weighted images by means of complex independent component analysis. Moreover, the combination of those features enables processing of the diffusion data absolutely user independent. Tractography from in vivo data and from a software phantom demonstrate the advantage of the spatially varying regularization compared to un-regularized data with respect to parameters relevant for fiber-tracking such as Mean Fiber Length, Track Count, Volume and Voxel Count. Specifically, for in vivo data findings suggest that tractography results from the regularized diffusion tensor based on one measurement (16 min generates results comparable to the un-regularized data with three averages (48 min. This significant reduction in scan time renders high resolution (1 × 1 × 2.5 mm(3 diffusion tensor imaging of the entire brain applicable in a clinical context.

  6. Diffusion tensor imaging fiber tracking with reliable tracking orientation and flexible step size☆

    Science.gov (United States)

    Yao, Xufeng; Wang, Manning; Chen, Xinrong; Nie, Shengdong; Li, Zhexu; Xu, Xiaoping; Zhang, Xuelong; Song, Zhijian

    2013-01-01

    We propose a method of reliable tracking orientation and flexible step size fiber tracking. A new directional strategy was defined to select one optimal tracking orientation from each directional set, which was based on the single-tensor model and the two-tensor model. The directional set of planar voxels contained three tracking directions: two from the two-tensor model and one from the single-tensor model. The directional set of linear voxels contained only one principal vector. In addition, a flexible step size, rather than fixable step sizes, was implemented to improve the accuracy of fiber tracking. We used two sets of human data to assess the performance of our method; one was from a healthy volunteer and the other from a patient with low-grade glioma. Results verified that our method was superior to the single-tensor Fiber Assignment by Continuous Tracking and the two-tensor eXtended Streamline Tractography for showing detailed images of fiber bundles. PMID:25206444

  7. Analyses of disruption of cerebral white matter integrity in schizophrenia with MR diffusion tensor fiber tracking method

    International Nuclear Information System (INIS)

    Yamamoto, Utako; Kobayashi, Tetsuo; Kito, Shinsuke; Koga, Yoshihiko

    2010-01-01

    We have analyzed cerebral white matter using magnetic resonance diffusion tensor imaging (MR-DTI) to measure the diffusion anisotropy of water molecules. The goal of this study is the quantitative evaluation of schizophrenia. Diffusion tensor images are acquired for patients with schizophrenia and healthy comparison subjects, group-matched for age, sex, and handedness. Fiber tracking is performed on the superior longitudinal fasciculus for the comparison between the patient and comparison groups. We have analysed and compared the cross-sectional area on the starting coronal plane and the mean and standard deviation of the fractional anisotropy and the apparent diffusion coefficient along fibers in the right and left hemispheres. In the right hemisphere, the cross-sectional areas in patient group are significantly smaller than those in the comparison group. Furthermore, in the comparison group, the cross-sectional areas in the right hemisphere are significantly larger than those in the left hemisphere, whereas there is no significant difference in the patient group. These results suggest that we may evaluate the disruption in white matter integrity in schizophrenic patients quantitatively by comparing the cross-sectional area of the superior longitudinal fasciculus in the right and left hemispheres. (author)

  8. Diffusion tensor imaging in spinal cord compression

    International Nuclear Information System (INIS)

    Wang, Wei; Qin, Wen; Hao, Nanxin; Wang, Yibin; Zong, Genlin

    2012-01-01

    Background Although diffusion tensor imaging has been successfully applied in brain research for decades, several main difficulties have hindered its extended utilization in spinal cord imaging. Purpose To assess the feasibility and clinical value of diffusion tensor imaging and tractography for evaluating chronic spinal cord compression. Material and Methods Single-shot spin-echo echo-planar DT sequences were scanned in 42 spinal cord compression patients and 49 healthy volunteers. The mean values of the apparent diffusion coefficient and fractional anisotropy were measured in region of interest at the cervical and lower thoracic spinal cord. The patients were divided into two groups according to the high signal on T2WI (the SCC-HI group and the SCC-nHI group for with or without high signal). A one-way ANOVA was used. Diffusion tensor tractography was used to visualize the morphological features of normal and impaired white matter. Results There were no statistically significant differences in the apparent diffusion coefficient and fractional anisotropy values between the different spinal cord segments of the normal subjects. All of the patients in the SCC-HI group had increased apparent diffusion coefficient values and decreased fractional anisotropy values at the lesion level compared to the normal controls. However, there were no statistically significant diffusion index differences between the SCC-nHI group and the normal controls. In the diffusion tensor imaging maps, the normal spinal cord sections were depicted as fiber tracts that were color-encoded to a cephalocaudal orientation. The diffusion tensor images were compressed to different degrees in all of the patients. Conclusion Diffusion tensor imaging and tractography are promising methods for visualizing spinal cord tracts and can provide additional information in clinical studies in spinal cord compression

  9. Ultrasound elastic tensor imaging: comparison with MR diffusion tensor imaging in the myocardium

    Science.gov (United States)

    Lee, Wei-Ning; Larrat, Benoît; Pernot, Mathieu; Tanter, Mickaël

    2012-08-01

    We have previously proven the feasibility of ultrasound-based shear wave imaging (SWI) to non-invasively characterize myocardial fiber orientation in both in vitro porcine and in vivo ovine hearts. The SWI-estimated results were in good correlation with histology. In this study, we proposed a new and robust fiber angle estimation method through a tensor-based approach for SWI, coined together as elastic tensor imaging (ETI), and compared it with magnetic resonance diffusion tensor imaging (DTI), a current gold standard and extensively reported non-invasive imaging technique for mapping fiber architecture. Fresh porcine (n = 5) and ovine (n = 5) myocardial samples (20 × 20 × 30 mm3) were studied. ETI was firstly performed to generate shear waves and to acquire the wave events at ultrafast frame rate (8000 fps). A 2.8 MHz phased array probe (pitch = 0.28 mm), connected to a prototype ultrasound scanner, was mounted on a customized MRI-compatible rotation device, which allowed both the rotation of the probe from -90° to 90° at 5° increments and co-registration between two imaging modalities. Transmural shear wave speed at all propagation directions realized was firstly estimated. The fiber angles were determined from the shear wave speed map using the least-squares method and eigen decomposition. The test myocardial sample together with the rotation device was then placed inside a 7T MRI scanner. Diffusion was encoded in six directions. A total of 270 diffusion-weighted images (b = 1000 s mm-2, FOV = 30 mm, matrix size = 60 × 64, TR = 6 s, TE = 19 ms, 24 averages) and 45 B0 images were acquired in 14 h 30 min. The fiber structure was analyzed by the fiber-tracking module in software, MedINRIA. The fiber orientation in the overlapped myocardial region which both ETI and DTI accessed was therefore compared, thanks to the co-registered imaging system. Results from all ten samples showed good correlation (r2 = 0.81, p 0.05, unpaired, one-tailed t-test, N = 10). In

  10. Spinal diffusion tensor imaging: a comprehensive review with emphasis on spinal cord anatomy and clinical applications.

    Science.gov (United States)

    Hendrix, Philipp; Griessenauer, Christoph J; Cohen-Adad, Julien; Rajasekaran, Shanmuganathan; Cauley, Keith A; Shoja, Mohammadali M; Pezeshk, Parham; Tubbs, R Shane

    2015-01-01

    Magnetic resonance imaging technology allows for in vivo visualization of fiber tracts of the central nervous system using diffusion-weighted imaging sequences and data processing referred to as "diffusion tensor imaging" and "diffusion tensor tractography." While protocols for high-fidelity diffusion tensor imaging of the brain are well established, the spinal cord has proven a more difficult target for diffusion tensor methods. Here, we review the current literature on spinal diffusion tensor imaging and tractography with special emphasis on neuroanatomical correlations and clinical applications. © 2014 Wiley Periodicals, Inc.

  11. Two-tensor streamline tractography through white matter intra-voxel fiber crossings

    DEFF Research Database (Denmark)

    Qazi, Arish Asif; Kindlmann, G; O'Donnell, L

    2008-01-01

    An inherent drawback of the traditional diffusion tensor model is its limited ability to provide detailed information about multidirectional fiber architecture within a voxel. This leads to erroneous fiber tractography results in locations where fiber bundles cross each other. In this paper, we p...

  12. Diffusion tensor imaging tensor shape analysis for assessment of regional white matter differences.

    Science.gov (United States)

    Middleton, Dana M; Li, Jonathan Y; Lee, Hui J; Chen, Steven; Dickson, Patricia I; Ellinwood, N Matthew; White, Leonard E; Provenzale, James M

    2017-08-01

    Purpose The purpose of this study was to investigate a novel tensor shape plot analysis technique of diffusion tensor imaging data as a means to assess microstructural differences in brain tissue. We hypothesized that this technique could distinguish white matter regions with different microstructural compositions. Methods Three normal canines were euthanized at seven weeks old. Their brains were imaged using identical diffusion tensor imaging protocols on a 7T small-animal magnetic resonance imaging system. We examined two white matter regions, the internal capsule and the centrum semiovale, each subdivided into an anterior and posterior region. We placed 100 regions of interest in each of the four brain regions. Eigenvalues for each region of interest triangulated onto tensor shape plots as the weighted average of three shape metrics at the plot's vertices: CS, CL, and CP. Results The distribution of data on the plots for the internal capsule differed markedly from the centrum semiovale data, thus confirming our hypothesis. Furthermore, data for the internal capsule were distributed in a relatively tight cluster, possibly reflecting the compact and parallel nature of its fibers, while data for the centrum semiovale were more widely distributed, consistent with the less compact and often crossing pattern of its fibers. This indicates that the tensor shape plot technique can depict data in similar regions as being alike. Conclusion Tensor shape plots successfully depicted differences in tissue microstructure and reflected the microstructure of individual brain regions. This proof of principle study suggests that if our findings are reproduced in larger samples, including abnormal white matter states, the technique may be useful in assessment of white matter diseases.

  13. FADTTS: functional analysis of diffusion tensor tract statistics.

    Science.gov (United States)

    Zhu, Hongtu; Kong, Linglong; Li, Runze; Styner, Martin; Gerig, Guido; Lin, Weili; Gilmore, John H

    2011-06-01

    The aim of this paper is to present a functional analysis of a diffusion tensor tract statistics (FADTTS) pipeline for delineating the association between multiple diffusion properties along major white matter fiber bundles with a set of covariates of interest, such as age, diagnostic status and gender, and the structure of the variability of these white matter tract properties in various diffusion tensor imaging studies. The FADTTS integrates five statistical tools: (i) a multivariate varying coefficient model for allowing the varying coefficient functions in terms of arc length to characterize the varying associations between fiber bundle diffusion properties and a set of covariates, (ii) a weighted least squares estimation of the varying coefficient functions, (iii) a functional principal component analysis to delineate the structure of the variability in fiber bundle diffusion properties, (iv) a global test statistic to test hypotheses of interest, and (v) a simultaneous confidence band to quantify the uncertainty in the estimated coefficient functions. Simulated data are used to evaluate the finite sample performance of FADTTS. We apply FADTTS to investigate the development of white matter diffusivities along the splenium of the corpus callosum tract and the right internal capsule tract in a clinical study of neurodevelopment. FADTTS can be used to facilitate the understanding of normal brain development, the neural bases of neuropsychiatric disorders, and the joint effects of environmental and genetic factors on white matter fiber bundles. The advantages of FADTTS compared with the other existing approaches are that they are capable of modeling the structured inter-subject variability, testing the joint effects, and constructing their simultaneous confidence bands. However, FADTTS is not crucial for estimation and reduces to the functional analysis method for the single measure. Copyright © 2011 Elsevier Inc. All rights reserved.

  14. Analytical performance bounds for multi-tensor diffusion-MRI.

    Science.gov (United States)

    Ahmed Sid, Farid; Abed-Meraim, Karim; Harba, Rachid; Oulebsir-Boumghar, Fatima

    2017-02-01

    To examine the effects of MR acquisition parameters on brain white matter fiber orientation estimation and parameter of clinical interest in crossing fiber areas based on the Multi-Tensor Model (MTM). We compute the Cramér-Rao Bound (CRB) for the MTM and the parameter of clinical interest such as the Fractional Anisotropy (FA) and the dominant fiber orientations, assuming that the diffusion MRI data are recorded by a multi-coil, multi-shell acquisition system. Considering the sum-of-squares method for the reconstructed magnitude image, we introduce an approximate closed-form formula for Fisher Information Matrix that has the simplicity and easy interpretation advantages. In addition, we propose to generalize the FA and the mean diffusivity to the multi-tensor model. We show the application of the CRB to reduce the scan time while preserving a good estimation precision. We provide results showing how the increase of the number of acquisition coils compensates the decrease of the number of diffusion gradient directions. We analyze the impact of the b-value and the Signal-to-Noise Ratio (SNR). The analysis shows that the estimation error variance decreases with a quadratic rate with the SNR, and that the optimum b-values are not unique but depend on the target parameter, the context, and eventually the target cost function. In this study we highlight the importance of choosing the appropriate acquisition parameters especially when dealing with crossing fiber areas. We also provide a methodology for the optimal tuning of these parameters using the CRB. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Homogeneity based segmentation and enhancement of Diffusion Tensor Images : a white matter processing framework

    OpenAIRE

    Rodrigues, P.R.

    2011-01-01

    In diffusion magnetic resonance imaging (DMRI) the Brownian motion of the water molecules, within biological tissue, is measured through a series of images. In diffusion tensor imaging (DTI) this diffusion is represented using tensors. DTI describes, in a non-invasive way, the local anisotropy pattern enabling the reconstruction of the nervous fibers - dubbed tractography. DMRI constitutes a powerful tool to analyse the structure of the white matter within a voxel, but also to investigate the...

  16. Diffusion tensor analysis with nuclear magnetic resonance in human central nervous system

    International Nuclear Information System (INIS)

    Nakayama, Naoki

    1998-01-01

    Nuclear magnetic resonance has been used to measure the diffusivity of water molecules. In central nervous system, anisotropic diffusion, which is characterized by apparent diffusion tensor D app ξ , is thought to be related to neuronal fiber tract orientation. For precise observation of anisotropic diffusion, it is needed to determine the diagonal and off-diagonal elements of D app ξ . Once D app ξ is estimated from a series of diffusion weighted images, a tissue's orthotropic principal axes and diffusivity of each direction are determined from eigenvalues and eigenvectors of D app ξ . There are several methods to represent anisotropic diffusion with D app ξ . Examples are diffusion ellipsoids constructed in each voxel depicting both these principal axes and the mean diffusion length in these directions, trace invariant values and its mapping image, largest eigenvalue, and ratio of largest eigenvalue to the other eigenvalue. In this study, the author investigated practical procedure to analyze diffusion tensor D app ξ using both of spin-echo end echo-planer diffusion weighted imagings with 3-tesla magnetic resonance machine in human brain. The ellipsoid representation provided particularly useful information about microanatomy including neuronal fiber tract orientation and molecular mobility reflective of microstructure. Furthermore, in the lesion of Wallerian degeneration, the loss of anisotropy of local apparent diffusion was observed. It is suggested that the function of axons can be observed via degree of anisotropy of apparent diffusion. Consequently, diffusion tensor analysis is expected to be a powerful, noninvasive method capable of quantitative and functional evaluation of the central nervous system. (author)

  17. Bayesian regularization of diffusion tensor images

    DEFF Research Database (Denmark)

    Frandsen, Jesper; Hobolth, Asger; Østergaard, Leif

    2007-01-01

    Diffusion tensor imaging (DTI) is a powerful tool in the study of the course of nerve fibre bundles in the human brain. Using DTI, the local fibre orientation in each image voxel can be described by a diffusion tensor which is constructed from local measurements of diffusion coefficients along...... several directions. The measured diffusion coefficients and thereby the diffusion tensors are subject to noise, leading to possibly flawed representations of the three dimensional fibre bundles. In this paper we develop a Bayesian procedure for regularizing the diffusion tensor field, fully utilizing...

  18. Evaluation of glymphatic system activity with the diffusion MR technique: diffusion tensor image analysis along the perivascular space (DTI-ALPS) in Alzheimer's disease cases.

    Science.gov (United States)

    Taoka, Toshiaki; Masutani, Yoshitaka; Kawai, Hisashi; Nakane, Toshiki; Matsuoka, Kiwamu; Yasuno, Fumihiko; Kishimoto, Toshifumi; Naganawa, Shinji

    2017-04-01

    The activity of the glymphatic system is impaired in animal models of Alzheimer's disease (AD). We evaluated the activity of the human glymphatic system in cases of AD with a diffusion-based technique called diffusion tensor image analysis along the perivascular space (DTI-ALPS). Diffusion tensor images were acquired to calculate diffusivities in the x, y, and z axes of the plane of the lateral ventricle body in 31 patients. We evaluated the diffusivity along the perivascular spaces as well as projection fibers and association fibers separately, to acquire an index for diffusivity along the perivascular space (ALPS-index) and correlated them with the mini mental state examinations (MMSE) score. We found a significant negative correlation between diffusivity along the projection fibers and association fibers. We also observed a significant positive correlation between diffusivity along perivascular spaces shown as ALPS-index and the MMSE score, indicating lower water diffusivity along the perivascular space in relation to AD severity. Activity of the glymphatic system may be evaluated with diffusion images. Lower diffusivity along the perivascular space on DTI-APLS seems to reflect impairment of the glymphatic system. This method may be useful for evaluating the activity of the glymphatic system.

  19. Identification of Stria Medullaris Fibers in the Massa Intermedia Using Diffusion Tensor Imaging.

    Science.gov (United States)

    Kochanski, Ryan B; Dawe, Robert; Kocak, Mehmet; Sani, Sepehr

    2018-04-01

    The massa intermedia (MI) or interthalamic adhesion is an inconsistent band spanning between bilateral medial thalami that is absent in up to 20%-30% of individuals. Little is known of its significance, especially in regard to functional pathways. Probabilistic diffusion tensor imaging (DTI) has recently been used to seed the lateral habenula and define its afferent white matter pathway, the stria medullaris thalami (SM). We sought to determine whether the MI serves as a conduit for crossing of limbic fibers such as the SM. Probabilistic DTI was performed on 10 subjects who had presence of a MI as visualized on magnetic resonance imaging. Tractography was also performed on 2 subjects without MI. Manual identification of the lateral habenula on axial T1-weighted magnetic resonance imaging was used for the initial seed region for tractography. In all subjects, the SM was reliably visualized. In 7 of the 10 subjects with MI, there was evidence of SM fibers that crossed to the ipsilateral hemisphere. Three subjects with small diameter MI did not have tractographic evidence of crossing SM fibers. Of the 7 subjects with crossing SM fibers within the MI, 5 showed predilection toward the right orbitofrontal cortex from both the left and right seed regions. Probabilistic DTI provides evidence of SM fibers within the MI. Given its anatomic location as a bridging pathway between thalami, further studies are necessary to assess its role within the limbic functional network. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Diffusion tensor magnetic resonance imaging for hand and foot fibers location at the corona radiata: comparison with two lesion studies

    Directory of Open Access Journals (Sweden)

    Dong-Hoon eLee

    2014-09-01

    Full Text Available The corticospinal tract is the motor pathway in the human brain, and corona radiata is an important location to diagnose stroke. We detected hand and foot motor fiber tracts in the corona radiata to investigate accurate locations using diffusion tensor imaging and functional imaging. Ten right-handed normal volunteers participated in this study. We used a probabilistic tracking algorithm, a brain normalization method, and functional imaging results to set out ROIs. Moreover, our results were compared to previous results of lesion studies to confirm their accuracy and usefulness. The location measurements were performed in two index types; anteriority index on the basis of the anterior and posterior location of lateral ventricle, laterality index on the basis of the left and right location. The anteriority indices were 56.40/43.2 (hand/foot at the upper CR and lower CR 40.72/30.90 at the lower CR. The measurements of anteriority and laterality of motor fibers were represented as anteriority index 0.40/0.31 and laterality index 0.60/0.47 (hand/foot. Our results showed that the hand and foot fibers were in good agreements with previous lesion studies. This study and approaches can be used as a standard for diffusion tensor image combined with lesion location studies in patients who need rehabilitation or follow up.

  1. Diffusion tensor imaging and fiber tractography in cervical compressive myelopathy: preliminary results

    International Nuclear Information System (INIS)

    Lee, Joon Woo; Kim, Jae Hyoung; Park, Jong Bin; Lee, Guen Young; Kang, Heung Sik; Park, Kun Woo; Yeom, Jin S.

    2011-01-01

    To assess diffusion tensor imaging (DTI) parameters in cervical compressive myelopathy (CCM) patients compared to normal volunteers, to relate them with myelopathy severity, and to relate tractography patterns with postoperative neurologic improvement. Twenty patients suffering from CCM were prospectively enrolled (M:F = 13:7, mean age, 49.6 years; range 22-67 years) from September 2009 to March 2010. Sensitivity encoding (SENSE) single-shot echo-planar imaging (EPI) was used for the sagittal DTI. Twenty sex- and age-matched normal volunteers underwent the same scanning procedure. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values in the spinal cord were compared between the patients and normal volunteers and were related to myelopathy severity based on Japanese Orthopedic Association (JOA) scores. Tractography patterns were related to myelopathy severity and postoperative improvement. There were significant differences between patients and normal volunteers in terms of FA (0.498 ± 0.114 vs. 0.604 ± 0.057; p = 0.001) and ADC (1.442 ± 0.389 vs. 1.169 ± 0.098; p = 0.001). DTI parameters and tractography patterns were not related to myelopathy severity. In ten patients in the neurologically worse group, postoperative neurologic improvement was seen in four of five patients with intact fiber tracts, but only one of five patients with interrupted fiber tracts exhibited neurologic improvement. DTI parameters in CCM patients were significantly different from those in normal volunteers but were not significantly related to myelopathy severity. The patterns of tractography appear to correlate with postoperative neurologic improvement. (orig.)

  2. Relationship between timed 25-foot walk and diffusion tensor imaging in multiple sclerosis.

    Science.gov (United States)

    Klineova, Sylvia; Farber, Rebecca; Saiote, Catarina; Farrell, Colleen; Delman, Bradley N; Tanenbaum, Lawrence N; Friedman, Joshua; Inglese, Matilde; Lublin, Fred D; Krieger, Stephen

    2016-01-01

    The majority of multiple sclerosis patients experience impaired walking ability, which impacts quality of life. Timed 25-foot walk is commonly used to gauge gait impairment but results can be broadly variable. Objective biological markers that correlate closely with patients' disability are needed. Diffusion tensor imaging, quantifying fiber tract integrity, might provide such information. In this project we analyzed relationships between timed 25-foot walk, conventional and diffusion tensor imaging magnetic resonance imaging markers. A cohort of gait impaired multiple sclerosis patients underwent brain and cervical spinal cord magnetic resonance imaging. Diffusion tensor imaging mean diffusivity and fractional anisotropy were measured on the brain corticospinal tracts and spinal restricted field of vision at C2/3. We analyzed relationships between baseline timed 25-foot walk, conventional and diffusion tensor imaging magnetic resonance imaging markers. Multivariate linear regression analysis showed a statistically significant association between several magnetic resonance imaging and diffusion tensor imaging metrics and timed 25-foot walk: brain mean diffusivity corticospinal tracts (p = 0.004), brain corticospinal tracts axial and radial diffusivity (P = 0.004 and 0.02), grey matter volume (p = 0.05), white matter volume (p = 0.03) and normalized brain volume (P = 0.01). The linear regression model containing mean diffusivity corticospinal tracts and controlled for gait assistance was the best fit model (p = 0.004). Our results suggest an association between diffusion tensor imaging metrics and gait impairment, evidenced by brain mean diffusivity corticospinal tracts and timed 25-foot walk.

  3. The direct tensor solution and higher-order acquisition schemes for generalized diffusion tensor imaging

    NARCIS (Netherlands)

    Akkerman, Erik M.

    2010-01-01

    Both in diffusion tensor imaging (DTI) and in generalized diffusion tensor imaging (GDTI) the relation between the diffusion tensor and the measured apparent diffusion coefficients is given by a tensorial equation, which needs to be inverted in order to solve the diffusion tensor. The traditional

  4. Volume illustration of muscle from diffusion tensor images.

    Science.gov (United States)

    Chen, Wei; Yan, Zhicheng; Zhang, Song; Crow, John Allen; Ebert, David S; McLaughlin, Ronald M; Mullins, Katie B; Cooper, Robert; Ding, Zi'ang; Liao, Jun

    2009-01-01

    Medical illustration has demonstrated its effectiveness to depict salient anatomical features while hiding the irrelevant details. Current solutions are ineffective for visualizing fibrous structures such as muscle, because typical datasets (CT or MRI) do not contain directional details. In this paper, we introduce a new muscle illustration approach that leverages diffusion tensor imaging (DTI) data and example-based texture synthesis techniques. Beginning with a volumetric diffusion tensor image, we reformulate it into a scalar field and an auxiliary guidance vector field to represent the structure and orientation of a muscle bundle. A muscle mask derived from the input diffusion tensor image is used to classify the muscle structure. The guidance vector field is further refined to remove noise and clarify structure. To simulate the internal appearance of the muscle, we propose a new two-dimensional example based solid texture synthesis algorithm that builds a solid texture constrained by the guidance vector field. Illustrating the constructed scalar field and solid texture efficiently highlights the global appearance of the muscle as well as the local shape and structure of the muscle fibers in an illustrative fashion. We have applied the proposed approach to five example datasets (four pig hearts and a pig leg), demonstrating plausible illustration and expressiveness.

  5. Reliable Dual Tensor Model Estimation in Single and Crossing Fibers Based on Jeffreys Prior

    Science.gov (United States)

    Yang, Jianfei; Poot, Dirk H. J.; Caan, Matthan W. A.; Su, Tanja; Majoie, Charles B. L. M.; van Vliet, Lucas J.; Vos, Frans M.

    2016-01-01

    Purpose This paper presents and studies a framework for reliable modeling of diffusion MRI using a data-acquisition adaptive prior. Methods Automated relevance determination estimates the mean of the posterior distribution of a rank-2 dual tensor model exploiting Jeffreys prior (JARD). This data-acquisition prior is based on the Fisher information matrix and enables the assessment whether two tensors are mandatory to describe the data. The method is compared to Maximum Likelihood Estimation (MLE) of the dual tensor model and to FSL’s ball-and-stick approach. Results Monte Carlo experiments demonstrated that JARD’s volume fractions correlated well with the ground truth for single and crossing fiber configurations. In single fiber configurations JARD automatically reduced the volume fraction of one compartment to (almost) zero. The variance in fractional anisotropy (FA) of the main tensor component was thereby reduced compared to MLE. JARD and MLE gave a comparable outcome in data simulating crossing fibers. On brain data, JARD yielded a smaller spread in FA along the corpus callosum compared to MLE. Tract-based spatial statistics demonstrated a higher sensitivity in detecting age-related white matter atrophy using JARD compared to both MLE and the ball-and-stick approach. Conclusions The proposed framework offers accurate and precise estimation of diffusion properties in single and dual fiber regions. PMID:27760166

  6. Diffusion tensor imaging and three-dimensional brain fiber tracking for the diagnosis of multiple sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Bing, Hu; Hong, Shan; Mingyue, Luo; Shaoqiong, Chen; Wang, Kang; Bingjun, He; Yan, Zou [Department of Radiology, the 3rd Affiliated Hospital of Sun Yat-sen Univ., Guangzhou (China); Binbin, Ye

    2007-02-15

    Objective: To demonstrate the diffusion tensor imaging (DTI) characteristics of multiple sclerosis (MS) plaques, periplaque white matter regions and normal appearing white matter (NAWM) regions in patients with MS, and to evaluate the clinical values of DTI and three-dimensional brain fiber tracking for the diagnosis of MS. Methods: Conventional MRI and DTI were performed in 32 patients with MS and 32 age-matched control subjects. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were generated and coregistered with T{sub 2}-weighted MR images. FA and ADC values were calculated in regions of interest in plaques, periplaque white matter regions, NAWM regions and white matter regions in control subjects. And three-dimensional brain fiber tracking maps were generated by using the DTI. Results: The ADC was (1.233 {+-} 0.119) x 10{sup -3} mm{sup 2}/s in MS plaques, (0.973 {+-} 0.098) x 10{sup -3} mm{sup 2}/s in periplaque white matter regions, (0.748 {+-} 0.089) x 10{sup -3} mm{sup 2}/s in NAWM, and (0.620 {+-} 0.094) x 10{sup -3} mm{sup 2}/s in control subjects. The FA was 0.225 {+-} 0.052 in MS plaques, 0.311 {+-} 0.050 in periplaque white matter regions, 0.421 {+-} 0.070 in NAWM, and 0.476 {+-} 0.069 in control subjects. Significant differences in FA and ADC values were observed among all white matter regions (P<0.01). MS plaques were demonstrated in three-dimensional brain fiber tracking maps. Conclusion: FA and ADC maps are helpful for the evaluation of all white matter changes of MS. The abnormalities of white matter fiber tracts in MS plaques could be demonstrated in three-dimensional brain fiber tracking maps. (authors)

  7. Diffusion tensor imaging and three-dimensional brain fiber tracking for the diagnosis of multiple sclerosis

    International Nuclear Information System (INIS)

    Hu Bing; Shan Hong; Luo Mingyue; Chen Shaoqiong; Kang Wang; He Bingjun; Zou Yan; Ye Binbin

    2007-01-01

    Objective: To demonstrate the diffusion tensor imaging (DTI) characteristics of multiple sclerosis (MS) plaques, periplaque white matter regions and normal appearing white matter (NAWM) regions in patients with MS, and to evaluate the clinical values of DTI and three-dimensional brain fiber tracking for the diagnosis of MS. Methods: Conventional MRI and DTI were performed in 32 patients with MS and 32 age-matched control subjects. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) maps were generated and coregistered with T 2 -weighted MR images. FA and ADC values were calculated in regions of interest in plaques, periplaque white matter regions, NAWM regions and white matter regions in control subjects. And three-dimensional brain fiber tracking maps were generated by using the DTI. Results: The ADC was (1.233 ± 0.119) x 10 -3 mm 2 /s in MS plaques, (0.973 ± 0.098) x 10 -3 mm 2 /s in periplaque white matter regions, (0.748 ± 0.089) x 10 -3 mm 2 /s in NAWM, and (0.620 ± 0.094) x 10 -3 mm 2 /s in control subjects. The FA was 0.225 ± 0.052 in MS plaques, 0.311 ± 0.050 in periplaque white matter regions, 0.421 ± 0.070 in NAWM, and 0.476 ± 0.069 in control subjects. Significant differences in FA and ADC values were observed among all white matter regions (P<0.01). MS plaques were demonstrated in three-dimensional brain fiber tracking maps. Conclusion: FA and ADC maps are helpful for the evaluation of all white matter changes of MS. The abnormalities of white matter fiber tracts in MS plaques could be demonstrated in three-dimensional brain fiber tracking maps. (authors)

  8. Automated segmentation of white matter fiber bundles using diffusion tensor imaging data and a new density based clustering algorithm.

    Science.gov (United States)

    Kamali, Tahereh; Stashuk, Daniel

    2016-10-01

    Robust and accurate segmentation of brain white matter (WM) fiber bundles assists in diagnosing and assessing progression or remission of neuropsychiatric diseases such as schizophrenia, autism and depression. Supervised segmentation methods are infeasible in most applications since generating gold standards is too costly. Hence, there is a growing interest in designing unsupervised methods. However, most conventional unsupervised methods require the number of clusters be known in advance which is not possible in most applications. The purpose of this study is to design an unsupervised segmentation algorithm for brain white matter fiber bundles which can automatically segment fiber bundles using intrinsic diffusion tensor imaging data information without considering any prior information or assumption about data distributions. Here, a new density based clustering algorithm called neighborhood distance entropy consistency (NDEC), is proposed which discovers natural clusters within data by simultaneously utilizing both local and global density information. The performance of NDEC is compared with other state of the art clustering algorithms including chameleon, spectral clustering, DBSCAN and k-means using Johns Hopkins University publicly available diffusion tensor imaging data. The performance of NDEC and other employed clustering algorithms were evaluated using dice ratio as an external evaluation criteria and density based clustering validation (DBCV) index as an internal evaluation metric. Across all employed clustering algorithms, NDEC obtained the highest average dice ratio (0.94) and DBCV value (0.71). NDEC can find clusters with arbitrary shapes and densities and consequently can be used for WM fiber bundle segmentation where there is no distinct boundary between various bundles. NDEC may also be used as an effective tool in other pattern recognition and medical diagnostic systems in which discovering natural clusters within data is a necessity. Copyright

  9. Microstructural changes in thickened corpus callosum in children: contribution of magnetic resonance diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Merlini, Laura; Anooshiravani, Mehrak; Kanavaki, Aikaterini; Hanquinet, Sylviane [University of Geneva Children' s Hospital, Pediatric Radiology Unit, Geneva (Switzerland)

    2015-06-15

    Thickened corpus callosum is a rare finding and its pathophysiology is not well known. An anomalous supracallosal bundle has been depicted by fiber tracking in some cases but no diffusion tensor imaging metrics of thickened corpus callosum have been reported. To use diffusion tensor imaging (DTI) in cases of thickened corpus callosum to help in understanding its clinical significance. During a 7-year period five children (ages 6 months to 15 years) with thickened corpus callosum were studied. We determined DTI metrics of fractional anisotropy (FA), mean diffusivity, and axial (λ1) and radial (λ2, λ3) diffusivity and performed 3-D fiber tracking reconstruction of the thickened corpus callosum. We compared our results with data from the literature and 24 age-matched controls. Brain abnormalities were seen in all cases. All children had at least three measurements of corpus callosum thickness above the 97th percentile according to age. In all children 3-D fiber tracking showed an anomalous supracallosal bundle and statistically significant decrease in FA (P = 0.003) and λ1 (P = 0.001) of the corpus callosum compared with controls, but no significant difference in mean diffusivity and radial diffusivity. Thickened corpus callosum was associated with abnormal bundles, suggesting underlying axonal guidance abnormality. DTI metrics suggested abnormal fiber compactness and density, which may be associated with alterations in cognition. (orig.)

  10. Diffusion tensor imaging. Theory, sequence optimization and application in Alzheimer's disease

    International Nuclear Information System (INIS)

    Stieltjes, B.; Schlueter, M.; Hahn, H.K.; Wilhelm, T.; Essig, M.

    2003-01-01

    Diffusion tensor imaging (DTI) offers an in vivo view into the microarchitecture of the brain. Furthermore it allows a three-dimensional reconstruction of fiber tracts. We will discuss the principles of DTI and possibilities for sequence optimization. Finally we will give an overview of DTI and its application in Alzheimer's disease. (orig.) [de

  11. 4.7-T diffusion tensor imaging of acute traumatic peripheral nerve injury.

    Science.gov (United States)

    Boyer, Richard B; Kelm, Nathaniel D; Riley, D Colton; Sexton, Kevin W; Pollins, Alonda C; Shack, R Bruce; Dortch, Richard D; Nanney, Lillian B; Does, Mark D; Thayer, Wesley P

    2015-09-01

    Diagnosis and management of peripheral nerve injury is complicated by the inability to assess microstructural features of injured nerve fibers via clinical examination and electrophysiology. Diffusion tensor imaging (DTI) has been shown to accurately detect nerve injury and regeneration in crush models of peripheral nerve injury, but no prior studies have been conducted on nerve transection, a surgical emergency that can lead to permanent weakness or paralysis. Acute sciatic nerve injuries were performed microsurgically to produce multiple grades of nerve transection in rats that were harvested 1 hour after surgery. High-resolution diffusion tensor images from ex vivo sciatic nerves were obtained using diffusion-weighted spin-echo acquisitions at 4.7 T. Fractional anisotropy was significantly reduced at the injury sites of transected rats compared with sham rats. Additionally, minor eigenvalues and radial diffusivity were profoundly elevated at all injury sites and were negatively correlated to the degree of injury. Diffusion tensor tractography showed discontinuities at all injury sites and significantly reduced continuous tract counts. These findings demonstrate that high-resolution DTI is a promising tool for acute diagnosis and grading of traumatic peripheral nerve injuries.

  12. Detection of Crossing White Matter Fibers with High-Order Tensors and Rank-k Decompositions

    KAUST Repository

    Jiao, Fangxiang; Gur, Yaniv; Johnson, Chris R.; Joshi, Sarang

    2011-01-01

    Fundamental to high angular resolution diffusion imaging (HARDI), is the estimation of a positive-semidefinite orientation distribution function (ODF) and extracting the diffusion properties (e.g., fiber directions). In this work we show that these two goals can be achieved efficiently by using homogeneous polynomials to represent the ODF in the spherical deconvolution approach, as was proposed in the Cartesian Tensor-ODF (CT-ODF) formulation. Based on this formulation we first suggest an estimation method for positive-semidefinite ODF by solving a linear programming problem that does not require special parameterization of the ODF. We also propose a rank-k tensor decomposition, known as CP decomposition, to extract the fibers information from the estimated ODF. We show that this decomposition is superior to the fiber direction estimation via ODF maxima detection as it enables one to reach the full fiber separation resolution of the estimation technique. We assess the accuracy of this new framework by applying it to synthetic and experimentally obtained HARDI data. © 2011 Springer-Verlag.

  13. Determination of mouse skeletal muscle architecture using three dimensional diffusion tensor imaging

    NARCIS (Netherlands)

    Heemskerk, A.M.; Strijkers, G.J.; Vilanova, A.; Drost, M.R.; Nicolaij, K.

    2005-01-01

    Muscle architecture is the main determinant of the mechanical behavior of skeletal muscles. This study explored the feasibility of diffusion tensor imaging (DTI) and fiber tracking to noninvasively determine the in vivo three-dimensional (3D) architecture of skeletal muscle in mouse hind leg. In six

  14. Determination of mouse skeletal muscle architecture using three-dimensional diffusion tensor imaging

    NARCIS (Netherlands)

    Heemskerk, Anneriet M.; Strijkers, Gustav J.; Vilanova, Anna; Drost, Maarten R.; Nicolay, Klaas

    2005-01-01

    Muscle architecture is the main determinant of the mechanical behavior of skeletal muscles. This study explored the feasibility of diffusion tensor imaging (DTI) and fiber tracking to noninvasively determine the in vivo three-dimensional (3D) architecture of skeletal muscle in mouse hind leg. In six

  15. Longitudinal study on diffusion tensor imaging and diffusion tensor tractography following spinal cord contusion injury in rats.

    Science.gov (United States)

    Zhao, Can; Rao, Jia-Sheng; Pei, Xiao-Jiao; Lei, Jian-Feng; Wang, Zhan-Jing; Yang, Zhao-Yang; Li, Xiao-Guang

    2016-06-01

    Diffusion tensor imaging (DTI) as a potential technology has been used in spinal cord injury (SCI) studies, but the longitudinal evaluation of DTI parameters after SCI, and the correlation between DTI parameters and locomotor outcomes need to be defined. Adult Wistar rats (n = 6) underwent traumatic thoracic cord contusion by an NYU impactor. DTI and Basso-Beattie-Bresnahan datasets were collected pre-SCI and 1, 3, 7, 14, and 84 days post-SCI. Diffusion tensor tractography (DTT) of the spinal cord was also generated. Fractional anisotropy (FA) and connection rate of fibers at the injury epicenter and at 5 mm rostral/caudal to the epicenter were calculated. The variations of these parameters after SCI were observed by one-way analysis of variance and the correlations between these parameters and motor function were explored by Pearson's correlation. FA at the epicenter decreased most remarkably on day 1 post-SCI (from 0.780 ± 0.012 to 0.330 ± 0.015), and continued to decrease slightly by day 3 post-SCI (0.313 ± 0.015), while other parameters decreased significantly over the first 3 days after SCI. DTT showed residual fibers concentrated on ventral and ventrolateral sides of the cord. Moreover, FA at the epicenter exhibited the strongest correlation (r = 0.887, p = 0.000) with the locomotion performance. FA was sensitive to degeneration in white matter and DTT could directly reflect the distribution of the residual white matter. Moreover, days 1 to 3 post-SCI may be the optimal time window for SCI examination and therapy.

  16. Evaluation of the differences of myocardial fibers between acute and chronic myocardial infarction: Application of diffusion tensor magnetic resonance imaging INA Rhesus monkey model

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu Qing; Cai, Wei; Wang, Lei; Xia, Rui; Chen, Wei; Zheng, Jie [Dept. of Radiology, West China Hospital, Sichuan University, Sichuan (China); Gao, Fabao [Mallinckrodt Institute of Radiology, School of Medicine, Washington University, St. Louis (United States)

    2016-09-15

    To understand microstructural changes after myocardial infarction (MI), we evaluated myocardial fibers of rhesus monkeys during acute or chronic MI, and identified the differences of myocardial fibers between acute and chronic MI. Six fixed hearts of rhesus monkeys with left anterior descending coronary artery ligation for 1 hour or 84 days were scanned by diffusion tensor magnetic resonance imaging (MRI) to measure apparent diffusion coefficient (ADC), fractional anisotropy (FA) and helix angle (HA). Comparing with acute MI monkeys (FA: 0.59 ± 0.02; ADC: 5.0 ± 0.6 × 10{sup -4} mm{sup 2}/s; HA: 94.5 ± 4.4°), chronic MI monkeys showed remarkably decreased FA value (0.26 ± 0.03), increased ADC value (7.8 ± 0.8 × 10{sup -4} mm{sup 2}/s), decreased HA transmural range (49.5 ± 4.6°) and serious defects on endocardium in infarcted regions. The HA in infarcted regions shifted to more components of negative left-handed helix in chronic MI monkeys (-38.3 ± 5.0°–11.2 ± 4.3°) than in acute MI monkeys (-41.4 ± 5.1°–53.1 ± 3.7°), but the HA in remote regions shifted to more components of positive right-handed helix in chronic MI monkeys (-43.8 ± 2.7°–66.5 ± 4.9°) than in acute MI monkeys (-59.5 ± 3.4°–64.9 ± 4.3°). Diffusion tensor MRI method helps to quantify differences of mechanical microstructure and water diffusion of myocardial fibers between acute and chronic MI monkey's models.

  17. Evaluation of the differences of myocardial fibers between acute and chronic myocardial infarction: Application of diffusion tensor magnetic resonance imaging INA Rhesus monkey model

    International Nuclear Information System (INIS)

    Wang, Yu Qing; Cai, Wei; Wang, Lei; Xia, Rui; Chen, Wei; Zheng, Jie; Gao, Fabao

    2016-01-01

    To understand microstructural changes after myocardial infarction (MI), we evaluated myocardial fibers of rhesus monkeys during acute or chronic MI, and identified the differences of myocardial fibers between acute and chronic MI. Six fixed hearts of rhesus monkeys with left anterior descending coronary artery ligation for 1 hour or 84 days were scanned by diffusion tensor magnetic resonance imaging (MRI) to measure apparent diffusion coefficient (ADC), fractional anisotropy (FA) and helix angle (HA). Comparing with acute MI monkeys (FA: 0.59 ± 0.02; ADC: 5.0 ± 0.6 × 10 -4 mm 2 /s; HA: 94.5 ± 4.4°), chronic MI monkeys showed remarkably decreased FA value (0.26 ± 0.03), increased ADC value (7.8 ± 0.8 × 10 -4 mm 2 /s), decreased HA transmural range (49.5 ± 4.6°) and serious defects on endocardium in infarcted regions. The HA in infarcted regions shifted to more components of negative left-handed helix in chronic MI monkeys (-38.3 ± 5.0°–11.2 ± 4.3°) than in acute MI monkeys (-41.4 ± 5.1°–53.1 ± 3.7°), but the HA in remote regions shifted to more components of positive right-handed helix in chronic MI monkeys (-43.8 ± 2.7°–66.5 ± 4.9°) than in acute MI monkeys (-59.5 ± 3.4°–64.9 ± 4.3°). Diffusion tensor MRI method helps to quantify differences of mechanical microstructure and water diffusion of myocardial fibers between acute and chronic MI monkey's models

  18. Diffusion tensor optical coherence tomography

    Science.gov (United States)

    Marks, Daniel L.; Blackmon, Richard L.; Oldenburg, Amy L.

    2018-01-01

    In situ measurements of diffusive particle transport provide insight into tissue architecture, drug delivery, and cellular function. Analogous to diffusion-tensor magnetic resonance imaging (DT-MRI), where the anisotropic diffusion of water molecules is mapped on the millimeter scale to elucidate the fibrous structure of tissue, here we propose diffusion-tensor optical coherence tomography (DT-OCT) for measuring directional diffusivity and flow of optically scattering particles within tissue. Because DT-OCT is sensitive to the sub-resolution motion of Brownian particles as they are constrained by tissue macromolecules, it has the potential to quantify nanoporous anisotropic tissue structure at micrometer resolution as relevant to extracellular matrices, neurons, and capillaries. Here we derive the principles of DT-OCT, relating the detected optical signal from a minimum of six probe beams with the six unique diffusion tensor and three flow vector components. The optimal geometry of the probe beams is determined given a finite numerical aperture, and a high-speed hardware implementation is proposed. Finally, Monte Carlo simulations are employed to assess the ability of the proposed DT-OCT system to quantify anisotropic diffusion of nanoparticles in a collagen matrix, an extracellular constituent that is known to become highly aligned during tumor development.

  19. Diffusion tensor MRI: clinical applications

    International Nuclear Information System (INIS)

    Meli, Francisco; Romero, Carlos; Carpintiero, Silvina; Salvatico, Rosana; Lambre, Hector; Vila, Jose

    2005-01-01

    Purpose: To evaluate the usefulness of diffusion-tensor imaging (DTI) on different neurological diseases, and to know if this technique shows additional information than conventional Magnetic Resonance Imaging (MRI). Materials and method: Eight patients, with neurological diseases (five patients with brain tumors, one with multiple sclerosis (MS), one with variant Creutzfeldt-Jakob disease (vCJD) and the other with delayed CO intoxication were evaluated. A MR scanner of 1.5 T was used and conventional sequences and DTI with twenty-five directions were done. Quantitative maps were gotten, where the fractional anisotropy (FA) through regions of interest (ROIs) in specific anatomic area were quantified (i.e.: internal and external capsules, frontal and temporal bundles, corpus fibers). Results: In the patients with brain tumors, there was a decrease of FA on intra and peritumoral fibers. Some of them had a disruption in their pattern. In patients with MS and CO intoxication, partial interruption along white matter bundles was demonstrated. However, a 'mismatch' between the findings of FLAIR, Diffusion-weighted images (DWI) and DTI, in the case of CO intoxication, was seen. Conclusions: DTI gave more information compared to conventional sequences about ultrastructural brain tissue in almost all the diseases above mentioned. Therefore, there is a work in progress about DTI acquisition, to evaluate a new technique, called tractography. (author)

  20. Reproducibility of corticospinal diffusion tensor tractography in normal subjects and hemiparetic stroke patients

    International Nuclear Information System (INIS)

    Lin, Chao-Chun; Tsai, Miao-Yu; Lo, Yu-Chien; Liu, Yi-Jui; Tsai, Po-Pang; Wu, Chiao-Ying; Lin, Chia-Wei; Shen, Wu-Chung; Chung, Hsiao-Wen

    2013-01-01

    Purpose: The reproducibility of corticospinal diffusion tensor tractography (DTT) for a guideline is important before longitudinal monitoring of the therapy effects in stroke patients. This study aimed to establish the reproducibility of corticospinal DTT indices in healthy subjects and chronic hemiparetic stroke patients. Materials and methods: Written informed consents were obtained from 10 healthy subjects (mean age 25.8 ± 6.8 years), who underwent two scans in one session plus the third scan one week later, and from 15 patients (mean age 47.5 ± 9.1 years, 6–60 months after the onset of stroke, NIHSS scores between 9 and 20) who were scanned thrice on separate days within one month. Diffusion-tensor imaging was performed at 3 T with 25 diffusion directions. Corticospinal tracts were reconstructed using fiber assignment by continuous tracking without and with motion/eddy-current corrections. Intra- and inter-rater as well as intra- and inter-session variations of the DTT derived indices (fiber number, apparent diffusion coefficient (ADC), and fractional anisotropy (FA)) were assessed. Results: Intra-session and inter-session coefficients of variations (CVs) are small for FA (1.13–2.09%) and ADC (0.45–1.64%), but much larger for fiber number (8.05–22.4%). Inter-session CVs in the stroke side of patients (22.4%) are higher than those in the normal sides (18.0%) and in the normal subjects (14.7%). Motion/eddy-current correction improved inter-session reproducibility only for the fiber number of the infarcted corticospinal tract (CV reduced from 22.4% to 14.1%). Conclusion: The fiber number derived from corticospinal DTT shows substantially lower precision than ADC and FA, with infarcted tracts showing lower reproducibility than the healthy tissues

  1. Evaluation of the Differences of Myocardial Fibers between Acute and Chronic Myocardial Infarction: Application of Diffusion Tensor Magnetic Resonance Imaging in a Rhesus Monkey Model

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuqing [Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041 (China); CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience and Technology of China, Beijing 100190 (China); Cai, Wei [Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041 (China); Department of Radiology, Beijing Jishuitan Hospital, 4th Clinical Medical College of Peking University, Beijing 100035 (China); Wang, Lei [Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041 (China); Xia, Rui [Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041 (China); Department of Radiology, The First Affiliated Hospital, Chongqing Medical University, Chongqing 400016 (China); Chen, Wei [Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041 (China); Department of Radiology, The First Affiliated Hospital of Kunming Medical University, Yunnan 650032 (China); Zheng, Jie [Mallinckrodt Institute of Radiology, School of Medicine, Washington University, St. Louis, MO 63110 (United States); Gao, Fabao [Department of Radiology, West China Hospital, Sichuan University, Sichuan 610041 (China)

    2016-11-01

    To understand microstructural changes after myocardial infarction (MI), we evaluated myocardial fibers of rhesus monkeys during acute or chronic MI, and identified the differences of myocardial fibers between acute and chronic MI. Six fixed hearts of rhesus monkeys with left anterior descending coronary artery ligation for 1 hour or 84 days were scanned by diffusion tensor magnetic resonance imaging (MRI) to measure apparent diffusion coefficient (ADC), fractional anisotropy (FA) and helix angle (HA). Comparing with acute MI monkeys (FA: 0.59 ± 0.02; ADC: 5.0 ± 0.6 × 10{sup -4} mm{sup 2}/s; HA: 94.5 ± 4.4°), chronic MI monkeys showed remarkably decreased FA value (0.26 ± 0.03), increased ADC value (7.8 ± 0.8 × 10{sup -4}mm{sup 2}/s), decreased HA transmural range (49.5 ± 4.6°) and serious defects on endocardium in infarcted regions. The HA in infarcted regions shifted to more components of negative left-handed helix in chronic MI monkeys (-38.3 ± 5.0°–11.2 ± 4.3°) than in acute MI monkeys (-41.4 ± 5.1°–53.1 ± 3.7°), but the HA in remote regions shifted to more components of positive right-handed helix in chronic MI monkeys (-43.8 ± 2.7°–66.5 ± 4.9°) than in acute MI monkeys (-59.5 ± 3.4°–64.9 ± 4.3°). Diffusion tensor MRI method helps to quantify differences of mechanical microstructure and water diffusion of myocardial fibers between acute and chronic MI monkey's models.

  2. Multi-component fiber track modelling of diffusion-weighted magnetic resonance imaging data

    Directory of Open Access Journals (Sweden)

    Yasser M. Kadah

    2010-01-01

    Full Text Available In conventional diffusion tensor imaging (DTI based on magnetic resonance data, each voxel is assumed to contain a single component having diffusion properties that can be fully represented by a single tensor. Even though this assumption can be valid in some cases, the general case involves the mixing of components, resulting in significant deviation from the single tensor model. Hence, a strategy that allows the decomposition of data based on a mixture model has the potential of enhancing the diagnostic value of DTI. This project aims to work towards the development and experimental verification of a robust method for solving the problem of multi-component modelling of diffusion tensor imaging data. The new method demonstrates significant error reduction from the single-component model while maintaining practicality for clinical applications, obtaining more accurate Fiber tracking results.

  3. Diffusion tensor tract-specific analysis of the uncinate fasciculus in patients with amyotrophic lateral sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Kanako; Masutani, Yoshitaka; Watadani, Takeyuki; Nakata, Yasuhiro; Yoshida, Mariko; Abe, Osamu; Ohtomo, Kuni [University of Tokyo, Department of Radiology, Graduate School of Medicine, Bunkyo, Tokyo (Japan); Aoki, Shigeki [Juntendo University, Department of Radiology, Bunkyo, Tokyo (Japan); Iwata, Nobue K.; Terao, Yasuo; Tsuji, Shoji [University of Tokyo, Department of Neurology, Graduate School of Medicine, Bunkyo, Tokyo (Japan)

    2010-08-15

    The uncinate fasciculus (UF) consists of core fibers connecting the frontal and temporal lobes and is considered to be related to cognitive/behavioral function. Using diffusion tensor tractography, we quantitatively evaluated changes in fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the UF by tract-specific analysis to evaluate the damage of the UF in patients with amyotrophic lateral sclerosis (ALS). We obtained diffusion tensor images of 15 patients with ALS and 9 age-matched volunteers. Patients with ALS showed significantly lower mean FA (P = 0.029) compared with controls. No significant difference was seen in mean ADC. The results suggest that damage of the UF in patients with ALS can be quantitatively evaluated with FA. (orig.)

  4. Effect of the Maximum Dose on White Matter Fiber Bundles Using Longitudinal Diffusion Tensor Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Tong; Chapman, Christopher H. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Tsien, Christina [Department of Radiation Oncology, Washington University at St Louis, St Louis, Missouri (United States); Kim, Michelle; Spratt, Daniel E.; Lawrence, Theodore S. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Cao, Yue, E-mail: yuecao@umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan (United States)

    2016-11-01

    Purpose: Previous efforts to decrease neurocognitive effects of radiation focused on sparing isolated cortical structures. We hypothesize that understanding temporal, spatial, and dosimetric patterns of radiation damage to whole-brain white matter (WM) after partial-brain irradiation might also be important. Therefore, we carried out a study to develop the methodology to assess radiation therapy (RT)–induced damage to whole-brain WM bundles. Methods and Materials: An atlas-based, automated WM tractography analysis was implemented to quantify longitudinal changes in indices of diffusion tensor imaging (DTI) of 22 major WM fibers in 33 patients with predominantly low-grade or benign brain tumors treated by RT. Six DTI scans per patient were performed from before RT to 18 months after RT. The DTI indices and planned doses (maximum and mean doses) were mapped onto profiles of each of 22 WM bundles. A multivariate linear regression was performed to determine the main dose effect as well as the influence of other clinical factors on longitudinal percentage changes in axial diffusivity (AD) and radial diffusivity (RD) from before RT. Results: Among 22 fiber bundles, AD or RD changes in 12 bundles were affected significantly by doses (P<.05), as the effect was progressive over time. In 9 elongated tracts, decreased AD or RD was significantly related to maximum doses received, consistent with a serial structure. In individual bundles, AD changes were up to 11.5% at the maximum dose locations 18 months after RT. The dose effect on WM was greater in older female patients than younger male patients. Conclusions: Our study demonstrates for the first time that the maximum dose to the elongated WM bundles causes post-RT damage in WM. Validation and correlative studies are necessary to determine the ability and impact of sparing these bundles on preserving neurocognitive function after RT.

  5. Characterization of short white matter fiber bundles in the central area from diffusion tensor MRI

    Energy Technology Data Exchange (ETDEWEB)

    Magro, Elsa [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Cavale Blanche, Service de Neurochirurgie, Pole Neurolocomoteur, Brest (France); Moreau, Tristan; Gibaud, Bernard [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); Seizeur, Romuald [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Cavale Blanche, Service de Neurochirurgie, Pole Neurolocomoteur, Brest (France); INSERM UMR 1101 LaTIM, Brest (France); Morandi, Xavier [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Pontchaillou, Service de Neurochirurgie, Rennes (France)

    2012-11-15

    Diffusion tensor imaging and tractography allow studying white matter fiber bundles in the human brain in vivo. Electrophysiological studies and postmortem dissections permit improving our knowledge about the short association fibers connecting the pre- and postcentral gyri. The aim of this study was first to extract and analyze the features of these short fiber bundles and secondly to analyze their asymmetry according to the subjects' handedness. Ten right-handed and ten left-handed healthy subjects were included. White matter fiber bundles were extracted using a streamline tractography approach, with two seed regions of interest (ROI) taken from a parcellation of the pre- and postcentral gyri. This parcellation was achieved using T1 magnetic resonance images (MRI) and semi-automatically generated three ROIs within each gyrus. MRI tracks were reconstructed between all pairs of ROIs connecting the adjacent pre- and postcentral gyri. A quantitative analysis was performed on the number of tracks connecting each ROI pair. A statistical analysis studied the repartition of these MRI tracks in the right and left hemispheres and as a function of the subjects' handedness. The quantitative analysis showed an increased density of MRI tracks in the middle part of the central area in each hemisphere of the 20 subjects. The statistical analysis showed significantly more MRI tracks for the left hemisphere, when we consider the whole population, and this difference was presumably driven by the left-handers. These results raise questions about the functional role of these MRI tracks and their relation with laterality. (orig.)

  6. Characterization of short white matter fiber bundles in the central area from diffusion tensor MRI

    International Nuclear Information System (INIS)

    Magro, Elsa; Moreau, Tristan; Gibaud, Bernard; Seizeur, Romuald; Morandi, Xavier

    2012-01-01

    Diffusion tensor imaging and tractography allow studying white matter fiber bundles in the human brain in vivo. Electrophysiological studies and postmortem dissections permit improving our knowledge about the short association fibers connecting the pre- and postcentral gyri. The aim of this study was first to extract and analyze the features of these short fiber bundles and secondly to analyze their asymmetry according to the subjects' handedness. Ten right-handed and ten left-handed healthy subjects were included. White matter fiber bundles were extracted using a streamline tractography approach, with two seed regions of interest (ROI) taken from a parcellation of the pre- and postcentral gyri. This parcellation was achieved using T1 magnetic resonance images (MRI) and semi-automatically generated three ROIs within each gyrus. MRI tracks were reconstructed between all pairs of ROIs connecting the adjacent pre- and postcentral gyri. A quantitative analysis was performed on the number of tracks connecting each ROI pair. A statistical analysis studied the repartition of these MRI tracks in the right and left hemispheres and as a function of the subjects' handedness. The quantitative analysis showed an increased density of MRI tracks in the middle part of the central area in each hemisphere of the 20 subjects. The statistical analysis showed significantly more MRI tracks for the left hemisphere, when we consider the whole population, and this difference was presumably driven by the left-handers. These results raise questions about the functional role of these MRI tracks and their relation with laterality. (orig.)

  7. Linear Invariant Tensor Interpolation Applied to Cardiac Diffusion Tensor MRI

    Science.gov (United States)

    Gahm, Jin Kyu; Wisniewski, Nicholas; Kindlmann, Gordon; Kung, Geoffrey L.; Klug, William S.; Garfinkel, Alan; Ennis, Daniel B.

    2015-01-01

    Purpose Various methods exist for interpolating diffusion tensor fields, but none of them linearly interpolate tensor shape attributes. Linear interpolation is expected not to introduce spurious changes in tensor shape. Methods Herein we define a new linear invariant (LI) tensor interpolation method that linearly interpolates components of tensor shape (tensor invariants) and recapitulates the interpolated tensor from the linearly interpolated tensor invariants and the eigenvectors of a linearly interpolated tensor. The LI tensor interpolation method is compared to the Euclidean (EU), affine-invariant Riemannian (AI), log-Euclidean (LE) and geodesic-loxodrome (GL) interpolation methods using both a synthetic tensor field and three experimentally measured cardiac DT-MRI datasets. Results EU, AI, and LE introduce significant microstructural bias, which can be avoided through the use of GL or LI. Conclusion GL introduces the least microstructural bias, but LI tensor interpolation performs very similarly and at substantially reduced computational cost. PMID:23286085

  8. Prediction of motor outcomes and activities of daily living function using diffusion tensor tractography in acute hemiparetic stroke patients.

    Science.gov (United States)

    Imura, Takeshi; Nagasawa, Yuki; Inagawa, Tetsuji; Imada, Naoki; Izumi, Hiroaki; Emoto, Katsuya; Tani, Itaru; Yamasaki, Hiroyuki; Ota, Yuichiro; Oki, Shuichi; Maeda, Tadanori; Araki, Osamu

    2015-05-01

    [Purpose] The efficacy of diffusion tensor imaging in the prediction of motor outcomes and activities of daily living function remains unclear. We evaluated the most appropriate diffusion tensor parameters and methodology to determine whether the region of interest- or tractography-based method was more useful for predicting motor outcomes and activities of daily living function in stroke patients. [Subjects and Methods] Diffusion tensor imaging data within 10 days after stroke onset were collected and analyzed for 25 patients. The corticospinal tract was analyzed. Fractional anisotropy, number of fibers, and apparent diffusion coefficient were used as diffusion tensor parameters. Motor outcomes and activities of daily living function were evaluated on the same day as diffusion tensor imaging and at 1 month post-onset. [Results] The fractional anisotropy value of the affected corticospinal tract significantly correlated with the motor outcome and activities of daily living function within 10 days post-onset and at 1 month post-onset. Tthere were no significant correlations between other diffusion tensor parameters and motor outcomes or activities of daily living function. [Conclusion] The fractional anisotropy value of the affected corticospinal tract obtained using the tractography-based method was useful for predicting motor outcomes and activities of daily living function in stroke patients.

  9. Diffusion tensor tractography as a supplementary tool to conventional MRI for evaluating patients with myelopathy

    Directory of Open Access Journals (Sweden)

    Amal Amin A. El Maati

    2014-12-01

    Conclusion: Diffusion tensor imaging is a reliable method for the evaluation of the diffusion properties of normal and compressed spinal cords. Furthermore, this technique can be used as an important supplementary tool to conventional MRI for the quantification of fiber damage in spinal cord compression, thus has the potential to be of great utility for treatment planning and follow up.

  10. Glyph-Based Comparative Visualization for Diffusion Tensor Fields.

    Science.gov (United States)

    Zhang, Changgong; Schultz, Thomas; Lawonn, Kai; Eisemann, Elmar; Vilanova, Anna

    2016-01-01

    Diffusion Tensor Imaging (DTI) is a magnetic resonance imaging modality that enables the in-vivo reconstruction and visualization of fibrous structures. To inspect the local and individual diffusion tensors, glyph-based visualizations are commonly used since they are able to effectively convey full aspects of the diffusion tensor. For several applications it is necessary to compare tensor fields, e.g., to study the effects of acquisition parameters, or to investigate the influence of pathologies on white matter structures. This comparison is commonly done by extracting scalar information out of the tensor fields and then comparing these scalar fields, which leads to a loss of information. If the glyph representation is kept, simple juxtaposition or superposition can be used. However, neither facilitates the identification and interpretation of the differences between the tensor fields. Inspired by the checkerboard style visualization and the superquadric tensor glyph, we design a new glyph to locally visualize differences between two diffusion tensors by combining juxtaposition and explicit encoding. Because tensor scale, anisotropy type, and orientation are related to anatomical information relevant for DTI applications, we focus on visualizing tensor differences in these three aspects. As demonstrated in a user study, our new glyph design allows users to efficiently and effectively identify the tensor differences. We also apply our new glyphs to investigate the differences between DTI datasets of the human brain in two different contexts using different b-values, and to compare datasets from a healthy and HIV-infected subject.

  11. Axon diameter mapping in crossing fibers with diffusion MRI

    DEFF Research Database (Denmark)

    Zhang, Hui; Dyrby, Tim B; Alexander, Daniel C

    2011-01-01

    This paper proposes a technique for a previously unaddressed problem, namely, mapping axon diameter in crossing fiber regions, using diffusion MRI. Direct measurement of tissue microstructure of this kind using diffusion MRI offers a new class of biomarkers that give more specific information about...... tissue than measures derived from diffusion tensor imaging. Most existing techniques for axon diameter mapping assume a single axon orientation in the tissue model, which limits their application to only the most coherently oriented brain white matter, such as the corpus callosum, where the single...... model to enable axon diameter mapping in voxels with crossing fibers. We show in simulation that the technique can provide robust axon diameter estimates in a two-fiber crossing with the crossing angle as small as 45 degrees. Using ex vivo imaging data, we further demonstrate the feasibility...

  12. Identification of the Occipito-Pontine Tract Using Diffusion-Tensor Fiber Tracking in Adult-Onset Adrenoleukodystrophy with Topographic Disorientation

    Directory of Open Access Journals (Sweden)

    Yuji Uchida

    2011-05-01

    Full Text Available X-linked adrenoleukodystrophy is a severe and progressive neurodegenerative disease caused by the peroxisomal transporter ATP-binding cassette, subfamily D, member 1 gene mutations. The defect of this gene product results in accumulation of very-long-chain fatty acids in organs and serum, central demyelination, and peripheral axonopathy. Although there are different magnetic resonance (MR findings which reflect various phenotypes in adrenoleukodystrophy, some cases present with specific symmetrical occipital white-matter lesions. We describe a patient with adult-onset X-linked adrenoleukodystrophy with topographic disorientation, whose brain MR images revealed T2-signal hyperintensity along the occipito-pontine tract and lateral lemnisci, but not in the cortico-spinal tract in the brainstem. The occipito-pontine tract and lateral lemnisci were clearly detected using diffusion-tensor fiber tracking, suggesting that the topographic disorientation of this patient might be related to the occipito-pontine tract. MR tractography can effectively identify the occipito-pontine tract and may help to localize the fibers associated with clinical symptoms.

  13. Studying Dynamic Myofiber Aggregate Reorientation in Dilated Cardiomyopathy Using In Vivo Magnetic Resonance Diffusion Tensor Imaging.

    Science.gov (United States)

    von Deuster, Constantin; Sammut, Eva; Asner, Liya; Nordsletten, David; Lamata, Pablo; Stoeck, Christian T; Kozerke, Sebastian; Razavi, Reza

    2016-10-01

    The objective of this study is to assess the dynamic alterations of myocardial microstructure and strain between diastole and systole in patients with dilated cardiomyopathy relative to healthy controls using the magnetic resonance diffusion tensor imaging, myocardial tagging, and biomechanical modeling. Dual heart-phase diffusion tensor imaging was successfully performed in 9 patients and 9 controls. Tagging data were acquired for the diffusion tensor strain correction and cardiac motion analysis. Mean diffusivity, fractional anisotropy, and myocyte aggregate orientations were compared between both cohorts. Cardiac function was assessed by left ventricular ejection fraction, torsion, and strain. Computational modeling was used to study the impact of cardiac shape on fiber reorientation and how fiber orientations affect strain. In patients with dilated cardiomyopathy, a more longitudinal orientation of diastolic myofiber aggregates was measured compared with controls. Although a significant steepening of helix angles (HAs) during contraction was found in the controls, consistent change in HAs during contraction was absent in patients. Left ventricular ejection fraction, cardiac torsion, and strain were significantly lower in the patients compared with controls. Computational modeling revealed that the dilated heart results in reduced HA changes compared with a normal heart. Reduced torsion was found to be exacerbated by steeper HAs. Diffusion tensor imaging revealed reduced reorientation of myofiber aggregates during cardiac contraction in patients with dilated cardiomyopathy relative to controls. Left ventricular remodeling seems to be an important factor in the changes to myocyte orientation. Steeper HAs are coupled with a worsening in strain and torsion. Overall, the findings provide new insights into the structural alterations in patients with dilated cardiomyopathy. © 2016 The Authors.

  14. 3D reconstruction of tensors and vectors

    International Nuclear Information System (INIS)

    Defrise, Michel; Gullberg, Grant T.

    2005-01-01

    Here we have developed formulations for the reconstruction of 3D tensor fields from planar (Radon) and line-integral (X-ray) projections of 3D vector and tensor fields. Much of the motivation for this work is the potential application of MRI to perform diffusion tensor tomography. The goal is to develop a theory for the reconstruction of both Radon planar and X-ray or line-integral projections because of the flexibility of MRI to obtain both of these type of projections in 3D. The development presented here for the linear tensor tomography problem provides insight into the structure of the nonlinear MRI diffusion tensor inverse problem. A particular application of tensor imaging in MRI is the potential application of cardiac diffusion tensor tomography for determining in vivo cardiac fiber structure. One difficulty in the cardiac application is the motion of the heart. This presents a need for developing future theory for tensor tomography in a motion field. This means developing a better understanding of the MRI signal for diffusion processes in a deforming media. The techniques developed may allow the application of MRI tensor tomography for the study of structure of fiber tracts in the brain, atherosclerotic plaque, and spine in addition to fiber structure in the heart. However, the relations presented are also applicable to other fields in medical imaging such as diffraction tomography using ultrasound. The mathematics presented can also be extended to exponential Radon transform of tensor fields and to other geometric acquisitions such as cone beam tomography of tensor fields

  15. A new study on diffusion tensor imaging of the whole visual pathway fiber bundle and clinical application

    Institute of Scientific and Technical Information of China (English)

    TAO Xiao-feng; WANG Zhong-qiu; GONG Wan-qing; JIANG Qing-jun; SHI Zeng-ru

    2009-01-01

    Background With conventional imaging methods only the morphous of the visual nerve fiber bundles can be demonstrated, while the earlier period functional changes can not be demonstrated. We hypothesized that diffusion tensor imaging (DTI) would demonstrated the whole optic never fiber bundle and visual pathway and the earlier period functional changes. The purpose of the present study was to evaluate the application of DTI technique in the demonstration of the whole optic never fiber bundle and visual pathway, and the influence of orbital tumors on them. Methods GE 1.5T signa HD MR System, and the software package DTV2 were adopted. The total 45 subjects were enrolled, including 15 volunteers and 30 patients. All patients had ocular proptosis from minor to major. Seven patients had visual acuity decrescence. Results The nerve fiber bundles, e.g. optic chiasma, optic tract and optic radiation in posterior visual pathway were well demonstrated in all cases. Wherein, the intact whole visual pathway fiber bundles were clearly revealed in 10 volunteers and 17 patients, and optic nerve was not wholly revealed in the rest of the subjects. Shift of optic nerve caused by compression and partial deformation were seen in 7 patients with orbital tumor. In 6 of 7 patients, DTI displayed significant abscise and deformation of visual nerve. Chi-square test indicated significant correlation between visual acuity decrescence and DTI visual nerve non-display. Conclusions Visual nerve fiber bundles and the whole visual pathway were visualized in most of patients with DTI. It might be an effective method of providing imaging evidence for visual nerve fiber earlier period functional changes, and laid a foundation for the study in other cranial nerves.

  16. FADTTSter: accelerating hypothesis testing with functional analysis of diffusion tensor tract statistics

    Science.gov (United States)

    Noel, Jean; Prieto, Juan C.; Styner, Martin

    2017-03-01

    Functional Analysis of Diffusion Tensor Tract Statistics (FADTTS) is a toolbox for analysis of white matter (WM) fiber tracts. It allows associating diffusion properties along major WM bundles with a set of covariates of interest, such as age, diagnostic status and gender, and the structure of the variability of these WM tract properties. However, to use this toolbox, a user must have an intermediate knowledge in scripting languages (MATLAB). FADTTSter was created to overcome this issue and make the statistical analysis accessible to any non-technical researcher. FADTTSter is actively being used by researchers at the University of North Carolina. FADTTSter guides non-technical users through a series of steps including quality control of subjects and fibers in order to setup the necessary parameters to run FADTTS. Additionally, FADTTSter implements interactive charts for FADTTS' outputs. This interactive chart enhances the researcher experience and facilitates the analysis of the results. FADTTSter's motivation is to improve usability and provide a new analysis tool to the community that complements FADTTS. Ultimately, by enabling FADTTS to a broader audience, FADTTSter seeks to accelerate hypothesis testing in neuroimaging studies involving heterogeneous clinical data and diffusion tensor imaging. This work is submitted to the Biomedical Applications in Molecular, Structural, and Functional Imaging conference. The source code of this application is available in NITRC.

  17. Interactive Volume Rendering of Diffusion Tensor Data

    Energy Technology Data Exchange (ETDEWEB)

    Hlawitschka, Mario; Weber, Gunther; Anwander, Alfred; Carmichael, Owen; Hamann, Bernd; Scheuermann, Gerik

    2007-03-30

    As 3D volumetric images of the human body become an increasingly crucial source of information for the diagnosis and treatment of a broad variety of medical conditions, advanced techniques that allow clinicians to efficiently and clearly visualize volumetric images become increasingly important. Interaction has proven to be a key concept in analysis of medical images because static images of 3D data are prone to artifacts and misunderstanding of depth. Furthermore, fading out clinically irrelevant aspects of the image while preserving contextual anatomical landmarks helps medical doctors to focus on important parts of the images without becoming disoriented. Our goal was to develop a tool that unifies interactive manipulation and context preserving visualization of medical images with a special focus on diffusion tensor imaging (DTI) data. At each image voxel, DTI provides a 3 x 3 tensor whose entries represent the 3D statistical properties of water diffusion locally. Water motion that is preferential to specific spatial directions suggests structural organization of the underlying biological tissue; in particular, in the human brain, the naturally occuring diffusion of water in the axon portion of neurons is predominantly anisotropic along the longitudinal direction of the elongated, fiber-like axons [MMM+02]. This property has made DTI an emerging source of information about the structural integrity of axons and axonal connectivity between brain regions, both of which are thought to be disrupted in a broad range of medical disorders including multiple sclerosis, cerebrovascular disease, and autism [Mos02, FCI+01, JLH+99, BGKM+04, BJB+03].

  18. Diffusion tensor smoothing through weighted Karcher means

    Science.gov (United States)

    Carmichael, Owen; Chen, Jun; Paul, Debashis; Peng, Jie

    2014-01-01

    Diffusion tensor magnetic resonance imaging (MRI) quantifies the spatial distribution of water Diffusion at each voxel on a regular grid of locations in a biological specimen by Diffusion tensors– 3 × 3 positive definite matrices. Removal of noise from DTI is an important problem due to the high scientific relevance of DTI and relatively low signal to noise ratio it provides. Leading approaches to this problem amount to estimation of weighted Karcher means of Diffusion tensors within spatial neighborhoods, under various metrics imposed on the space of tensors. However, it is unclear how the behavior of these estimators varies with the magnitude of DTI sensor noise (the noise resulting from the thermal e!ects of MRI scanning) as well as the geometric structure of the underlying Diffusion tensor neighborhoods. In this paper, we combine theoretical analysis, empirical analysis of simulated DTI data, and empirical analysis of real DTI scans to compare the noise removal performance of three kernel-based DTI smoothers that are based on Euclidean, log-Euclidean, and affine-invariant metrics. The results suggest, contrary to conventional wisdom, that imposing a simplistic Euclidean metric may in fact provide comparable or superior noise removal, especially in relatively unstructured regions and/or in the presence of moderate to high levels of sensor noise. On the contrary, log-Euclidean and affine-invariant metrics may lead to better noise removal in highly structured anatomical regions, especially when the sensor noise is of low magnitude. These findings emphasize the importance of considering the interplay of sensor noise magnitude and tensor field geometric structure when assessing Diffusion tensor smoothing options. They also point to the necessity for continued development of smoothing methods that perform well across a large range of scenarios. PMID:25419264

  19. Mean magnetic susceptibility regularized susceptibility tensor imaging (MMSR-STI) for estimating orientations of white matter fibers in human brain.

    Science.gov (United States)

    Li, Xu; van Zijl, Peter C M

    2014-09-01

    An increasing number of studies show that magnetic susceptibility in white matter fibers is anisotropic and may be described by a tensor. However, the limited head rotation possible for in vivo human studies leads to an ill-conditioned inverse problem in susceptibility tensor imaging (STI). Here we suggest the combined use of limiting the susceptibility anisotropy to white matter and imposing morphology constraints on the mean magnetic susceptibility (MMS) for regularizing the STI inverse problem. The proposed MMS regularized STI (MMSR-STI) method was tested using computer simulations and in vivo human data collected at 3T. The fiber orientation estimated from both the STI and MMSR-STI methods was compared to that from diffusion tensor imaging (DTI). Computer simulations show that the MMSR-STI method provides a more accurate estimation of the susceptibility tensor than the conventional STI approach. Similarly, in vivo data show that use of the MMSR-STI method leads to a smaller difference between the fiber orientation estimated from STI and DTI for most selected white matter fibers. The proposed regularization strategy for STI can improve estimation of the susceptibility tensor in white matter. © 2014 Wiley Periodicals, Inc.

  20. [An Improved Spectral Quaternion Interpolation Method of Diffusion Tensor Imaging].

    Science.gov (United States)

    Xu, Yonghong; Gao, Shangce; Hao, Xiaofei

    2016-04-01

    Diffusion tensor imaging(DTI)is a rapid development technology in recent years of magnetic resonance imaging.The diffusion tensor interpolation is a very important procedure in DTI image processing.The traditional spectral quaternion interpolation method revises the direction of the interpolation tensor and can preserve tensors anisotropy,but the method does not revise the size of tensors.The present study puts forward an improved spectral quaternion interpolation method on the basis of traditional spectral quaternion interpolation.Firstly,we decomposed diffusion tensors with the direction of tensors being represented by quaternion.Then we revised the size and direction of the tensor respectively according to different situations.Finally,we acquired the tensor of interpolation point by calculating the weighted average.We compared the improved method with the spectral quaternion method and the Log-Euclidean method by the simulation data and the real data.The results showed that the improved method could not only keep the monotonicity of the fractional anisotropy(FA)and the determinant of tensors,but also preserve the tensor anisotropy at the same time.In conclusion,the improved method provides a kind of important interpolation method for diffusion tensor image processing.

  1. Microsurgical anatomy of the ventral callosal radiations: new destination, correlations with diffusion tensor imaging fiber-tracking, and clinical relevance.

    Science.gov (United States)

    Peltier, Johann; Verclytte, Sébastien; Delmaire, Christine; Deramond, Hervé; Pruvo, Jean-Pierre; Le Gars, Daniel; Godefroy, Olivier

    2010-03-01

    In the current literature, there is a lack of a detailed map of the origin, course, and connections of the ventral callosal radiations of the human brain. The authors used an older dissection technique based on a freezing process as well as diffusion tensor imaging to investigate this area of the human brain. The authors demonstrated interconnections between areas 11, 12, and 25 for the callosal radiations of the trunk and rostrum of the corpus callosum; between areas 9, 10, and 32 for the genu; and between areas 6, 8, and 9 for the ventral third of the body. The authors identified new ventral callosal connections crossing the rostrum between both temporal poles and coursing within the temporal stem, and they named these connections the "callosal radiations of Peltier." They found that the breadth of the callosal radiations slightly increases along their course from the rostrum to the first third of the body of the corpus callosum. The fiber dissection and diffusion tensor imaging techniques are complementary not only in their application to the study of the commissural system in the human brain, but also in their practical use for diagnosis and surgical planning. Further investigations, neurocognitive tests, and other contributions will permit elucidation of the functional relevance of the newly identified callosal radiations in patients with disease involving the ventral corpus callosum.

  2. Voxel-wise comparisons of the morphology of diffusion tensors across groups of experimental subjects

    DEFF Research Database (Denmark)

    Bansal, Ravi; Staib, Lawrence H; Plessen, Kerstin J

    2007-01-01

    method to compute their approximate covariance matrices. Our results show that the theoretically computed mean tensor (MT) eigenvectors and eigenvalues match well with their respective true values. Furthermore, a comparison of synthetically generated groups of DTs highlights the limitations of using FA...... to detect group differences. Finally, analyses of in vivo DT data using our method reveal significant between-group differences in diffusivity along fiber tracts within white matter, whereas analyses based on FA values failed to detect some of these differences....... neuropsychiatric illnesses. Comparisons of tensor morphology across groups have typically been performed on scalar measures of diffusivity, such as Fractional Anisotropy (FA) rather than directly on the complex 3D morphologies of DTs. Scalar measures, however, are related in nonlinear ways to the eigenvalues...

  3. Determination of mouse skeletal muscle architecture using three-dimensional diffusion tensor imaging.

    Science.gov (United States)

    Heemskerk, Anneriet M; Strijkers, Gustav J; Vilanova, Anna; Drost, Maarten R; Nicolay, Klaas

    2005-06-01

    Muscle architecture is the main determinant of the mechanical behavior of skeletal muscles. This study explored the feasibility of diffusion tensor imaging (DTI) and fiber tracking to noninvasively determine the in vivo three-dimensional (3D) architecture of skeletal muscle in mouse hind leg. In six mice, the hindlimb was imaged with a diffusion-weighted (DW) 3D fast spin-echo (FSE) sequence followed by the acquisition of an exercise-induced, T(2)-enhanced data set. The data showed the expected fiber organization, from which the physiological cross-sectional area (PCSA), fiber length, and pennation angle for the tibialis anterior (TA) were obtained. The values of these parameters ranged from 5.4-9.1 mm(2), 5.8-7.8 mm, and 21-24 degrees , respectively, which is in agreement with values obtained previously with the use of invasive methods. This study shows that 3D DT acquisition and fiber tracking is feasible for the skeletal muscle of mice, and thus enables the quantitative determination of muscle architecture.

  4. The tensor distribution function.

    Science.gov (United States)

    Leow, A D; Zhu, S; Zhan, L; McMahon, K; de Zubicaray, G I; Meredith, M; Wright, M J; Toga, A W; Thompson, P M

    2009-01-01

    Diffusion weighted magnetic resonance imaging is a powerful tool that can be employed to study white matter microstructure by examining the 3D displacement profile of water molecules in brain tissue. By applying diffusion-sensitized gradients along a minimum of six directions, second-order tensors (represented by three-by-three positive definite matrices) can be computed to model dominant diffusion processes. However, conventional DTI is not sufficient to resolve more complicated white matter configurations, e.g., crossing fiber tracts. Recently, a number of high-angular resolution schemes with more than six gradient directions have been employed to address this issue. In this article, we introduce the tensor distribution function (TDF), a probability function defined on the space of symmetric positive definite matrices. Using the calculus of variations, we solve the TDF that optimally describes the observed data. Here, fiber crossing is modeled as an ensemble of Gaussian diffusion processes with weights specified by the TDF. Once this optimal TDF is determined, the orientation distribution function (ODF) can easily be computed by analytic integration of the resulting displacement probability function. Moreover, a tensor orientation distribution function (TOD) may also be derived from the TDF, allowing for the estimation of principal fiber directions and their corresponding eigenvalues.

  5. Fiber density estimation from single q-shell diffusion imaging by tensor divergence.

    Science.gov (United States)

    Reisert, Marco; Mader, Irina; Umarova, Roza; Maier, Simon; Tebartz van Elst, Ludger; Kiselev, Valerij G

    2013-08-15

    Diffusion-weighted magnetic resonance imaging provides information about the nerve fiber bundle geometry of the human brain. While the inference of the underlying fiber bundle orientation only requires single q-shell measurements, the absolute determination of their volume fractions is much more challenging with respect to measurement techniques and analysis. Unfortunately, the usually employed multi-compartment models cannot be applied to single q-shell measurements, because the compartment's diffusivities cannot be resolved. This work proposes an equation for fiber orientation densities that can infer the absolute fraction up to a global factor. This equation, which is inspired by the classical mass preservation law in fluid dynamics, expresses the fiber conservation associated with the assumption that fibers do not terminate in white matter. Simulations on synthetic phantoms show that the approach is able to derive the densities correctly for various configurations. Experiments with a pseudo ground truth phantom show that even for complex, brain-like geometries the method is able to infer the densities correctly. In-vivo results with 81 healthy volunteers are plausible and consistent. A group analysis with respect to age and gender show significant differences, such that the proposed maps can be used as a quantitative measure for group and longitudinal analysis. Copyright © 2013 Elsevier Inc. All rights reserved.

  6. Segmentation of the canine corpus callosum using diffusion-tensor imaging tractography.

    Science.gov (United States)

    Pierce, Theodore T; Calabrese, Evan; White, Leonard E; Chen, Steven D; Platt, Simon R; Provenzale, James M

    2014-01-01

    We set out to determine functional white matter (WM) connections passing through the canine corpus callosum; these WM connections would be useful for subsequent studies of canine brains that serve as models for human WM pathway disease. Based on prior studies, we anticipated that the anterior corpus callosum would send projections to the anterior cerebral cortex whereas progressively posterior segments would send projections to more posterior cortex. A postmortem canine brain was imaged using a 7-T MRI system producing 100-μm-isotropic-resolution diffusion-tensor imaging analyzed by tractography. Using regions of interest (ROIs) within cortical locations, which were confirmed by a Nissl stain that identified distinct cortical architecture, we successfully identified six important WM pathways. We also compared fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity, and axial diffusivity in tracts passing through the genu and splenium. Callosal fibers were organized on the basis of cortical destination (e.g., fibers from the genu project to the frontal cortex). Histologic results identified the motor cortex on the basis of cytoarchitectonic criteria that allowed placement of ROIs to discriminate between frontal and parietal lobes. We also identified cytoarchitecture typical of the orbital frontal, anterior frontal, and occipital regions and placed ROIs accordingly. FA, ADC, radial diffusivity, and axial diffusivity values were all higher in posterior corpus callosum fiber tracts. Using six cortical ROIs, we identified six major WM tracts that reflect major functional divisions of the cerebral hemispheres, and we derived quantitative values that can be used for study of canine models of human WM pathologic states.

  7. Diffusion tensor image registration using hybrid connectivity and tensor features.

    Science.gov (United States)

    Wang, Qian; Yap, Pew-Thian; Wu, Guorong; Shen, Dinggang

    2014-07-01

    Most existing diffusion tensor imaging (DTI) registration methods estimate structural correspondences based on voxelwise matching of tensors. The rich connectivity information that is given by DTI, however, is often neglected. In this article, we propose to integrate complementary information given by connectivity features and tensor features for improved registration accuracy. To utilize connectivity information, we place multiple anchors representing different brain anatomies in the image space, and define the connectivity features for each voxel as the geodesic distances from all anchors to the voxel under consideration. The geodesic distance, which is computed in relation to the tensor field, encapsulates information of brain connectivity. We also extract tensor features for every voxel to reflect the local statistics of tensors in its neighborhood. We then combine both connectivity features and tensor features for registration of tensor images. From the images, landmarks are selected automatically and their correspondences are determined based on their connectivity and tensor feature vectors. The deformation field that deforms one tensor image to the other is iteratively estimated and optimized according to the landmarks and their associated correspondences. Experimental results show that, by using connectivity features and tensor features simultaneously, registration accuracy is increased substantially compared with the cases using either type of features alone. Copyright © 2013 Wiley Periodicals, Inc.

  8. Diffusion tensor MR microscopy of tissues with low diffusional anisotropy.

    Science.gov (United States)

    Bajd, Franci; Mattea, Carlos; Stapf, Siegfried; Sersa, Igor

    2016-06-01

    Diffusion tensor imaging exploits preferential diffusional motion of water molecules residing within tissue compartments for assessment of tissue structural anisotropy. However, instrumentation and post-processing errors play an important role in determination of diffusion tensor elements. In the study, several experimental factors affecting accuracy of diffusion tensor determination were analyzed. Effects of signal-to-noise ratio and configuration of the applied diffusion-sensitizing gradients on fractional anisotropy bias were analyzed by means of numerical simulations. In addition, diffusion tensor magnetic resonance microscopy experiments were performed on a tap water phantom and bovine articular cartilage-on-bone samples to verify the simulation results. In both, the simulations and the experiments, the multivariate linear regression of the diffusion-tensor analysis yielded overestimated fractional anisotropy with low SNRs and with low numbers of applied diffusion-sensitizing gradients. An increase of the apparent fractional anisotropy due to unfavorable experimental conditions can be overcome by applying a larger number of diffusion sensitizing gradients with small values of the condition number of the transformation matrix. This is in particular relevant in magnetic resonance microscopy, where imaging gradients are high and the signal-to-noise ratio is low.

  9. Traumatic brain injury and the post-concussion syndrome: A diffusion tensor tractography study

    International Nuclear Information System (INIS)

    D’souza, Maria M; Trivedi, Richa; Singh, Kavita; Grover, Hemal; Choudhury, Ajay; Kaur, Prabhjot; Kumar, Pawan; Tripathi, Rajendra Prashad

    2015-01-01

    The aim of the present study is to evaluate diffusion tensor tractography (DTT) as a tool for detecting diffuse axonal injury in patients of acute, mild, and moderate traumatic brain injury (TBI), using two diffusion variables: Fractional anisotropy (FA) and mean diffusivity (MD). The correlation of these indices with the severity of post-concussive symptoms was also assessed. Nineteen patients with acute, mild, or moderate TBI and twelve age- and sex-matched healthy controls were recruited. Following Magnetic Resonance Imaging (MRI) on a 3.0-T scanner, DTT was performed using the ‘fiber assignment by continuous tracking’ (FACT) algorithm for fiber reconstruction. Appropriate statistical tools were used to see the difference in FA and MD values between the control and patient groups. In the latter group, the severity of post-concussive symptoms was assessed six months following trauma, using the Rivermead Postconcussion Symptoms Questionnaire (RPSQ). The patients displayed significant reduction in FA compared to the controls (P < 0.05) in several tracts, notably the corpus callosum, fornix, bilateral uncinate fasciculus, and bilateral superior thalamic radiations. Changes in MD were statistically significant in the left uncinate, inferior longitudinal fasciculus, and left posterior thalamic radiation. A strong correlation between these indices and the RPSQ scores was observed in several white matter tracts. Diffusion tensor imaging (DTI)-based quantitative analysis in acute, mild, and moderate TBI can identify axonal injury neuropathology, over and above that visualized on conventional MRI scans. Furthermore, the significant correlation observed between FA and MD indices and the severity of post-concussive symptoms could make it a useful predictor of the long-term outcome

  10. X-linked adrenoleukodystrophy: correlation between Loes score and diffusion tensor imaging parameters.

    Science.gov (United States)

    Ono, Sergio Eiji; de Carvalho Neto, Arnolfo; Gasparetto, Emerson Leandro; Coelho, Luiz Otávio de Mattos; Escuissato, Dante Luiz; Bonfim, Carmem Maria Sales; Ribeiro, Lisandro Lima

    2014-01-01

    The present study was aimed at evaluating the correlation between diffusion tensor imaging parameters and Loes score as well as whether those parameters could indicate early structural alterations. Diffusion tensor imaging measurements were obtained in 30 studies of 14 patients with X-linked adrenoleukodystrophy and were correlated with Loes scores. A control group including 28 male patients was created to establish agematched diffusion tensor imaging measurements. Inter- and intraobserver statistical analyses were undertaken. Diffusion tensor imaging measurements presented strong Pearson correlation coefficients (r) of -0.86, 0.89, 0.89 and 0.84 for fractional anisotropy and mean, radial and axial diffusivities (p tensor measurements at early stage of the disease indicates that mean and radial diffusivities might be useful to predict the disease progression. Measurements of diffusion tensor parameters can be used as an adjunct to the Loes score, aiding in the monitoring of the disease and alerting for possible Loes score progression in the range of interest for therapeutic decisions.

  11. Imaging Arterial Fibres Using Diffusion Tensor Imaging—Feasibility Study and Preliminary Results

    Directory of Open Access Journals (Sweden)

    Kerskens Christian

    2010-01-01

    Full Text Available Abstract MR diffusion tensor imaging (DTI was used to analyze the fibrous structure of aortic tissue. A fresh porcine aorta was imaged at 7T using a spin echo sequence with the following parameters: matrix 128 128 pixel; slice thickness 0.5 mm; interslice spacing 0.1 mm; number of slices 16; echo time 20.3 s; field of view 28 mm 28 mm. Eigenvectors from the diffusion tensor images were calculated for the central image slice and the averaged tensors and the eigenvector corresponding to the largest eigenvalue showed two distinct angles corresponding to near and to the transverse plane of the aorta. Fibre tractography within the aortic volume imaged confirmed that fibre angles were oriented helically with lead angles of and . The findings correspond to current histological and microscopy data on the fibrous structure of aortic tissue, and therefore the eigenvector maps and fibre tractography appear to reflect the alignment of the fibers in the aorta. In view of current efforts to develop noninvasive diagnostic tools for cardiovascular diseases, DTI may offer a technique to assess the structural properties of arterial tissue and hence any changes or degradation in arterial tissue.

  12. Distribution of collateral fibers in the monkey cervical spinal cord detected with diffusion-weighted magnetic resonance imaging

    DEFF Research Database (Denmark)

    Lundell, Henrik; Nielsen, Jens Bo; Ptito, Maurice

    2011-01-01

    techniques. We calculate the diffusion tensor and the persistent angular structure (PAS), a multi-fiber reconstruction technique, from high quality post mortem data of a perfusion-fixed vervet monkey cervical spinal cord sample and simulated crossing fiber data. Our results show that (i) cylindrical geometry...

  13. Higher-order tensors in diffusion imaging

    NARCIS (Netherlands)

    Schultz, T.; Fuster, A.; Ghosh, A.; Deriche, R.; Florack, L.M.J.; Lim, L.H.; Westin, C.-F.; Vilanova, A.; Burgeth, B.

    2014-01-01

    Diffusion imaging is a noninvasive tool for probing the microstructure of fibrous nerve and muscle tissue. Higher-order tensors provide a powerful mathematical language to model and analyze the large and complex data that is generated by its modern variants such as High Angular Resolution Diffusion

  14. Radiation-Induced Changes in Normal-Appearing White Matter in Patients With Cerebral Tumors: A Diffusion Tensor Imaging Study

    International Nuclear Information System (INIS)

    Nagesh, Vijaya; Tsien, Christina I.; Chenevert, Thomas L.; Ross, Brian D.; Lawrence, Theodore S.; Junick, Larry; Cao Yue

    2008-01-01

    Purpose: To quantify the radiation-induced changes in normal-appearing white matter before, during, and after radiotherapy (RT) in cerebral tumor patients. Methods and Materials: Twenty-five patients with low-grade glioma, high-grade glioma, or benign tumor treated with RT were studied using diffusion tensor magnetic resonance imaging. The biologically corrected doses ranged from 50 to 81 Gy. The temporal changes were assessed before, during, and to 45 weeks after the start of RT. The mean diffusivity of water ( ), fractional anisotropy of diffusion, diffusivity perpendicular (λ perpendicular ) and parallel (λ parallel ) to white matter fibers were calculated in normal-appearing genu and splenium of the corpus callosum. Results: In the genu and splenium, fractional anisotropy decreased and , λ parallel , λ -perpendicular increased linearly and significantly with time (p -perpendicular had increased ∼30% in the genu and splenium, and λ parallel had increased 5% in the genu and 9% in the splenium, suggesting that demyelination is predominant. The increases in λ perpendicular and λ parallel were dose dependent, starting at 3 weeks and continuing to 32 weeks from the start of RT. The dose-dependent increase in λ perpendicular and λ parallel was not sustained after 32 weeks, indicating the transition from focal to diffuse effects. Conclusion: The acute and subacute changes in normal-appearing white matter fibers indicate radiation-induced demyelination and mild structural degradation of axonal fibers. The structural changes after RT are progressive, with early dose-dependent demyelination and subsequent diffuse dose-independent demyelination and mild axonal degradation. Diffusion tensor magnetic resonance imaging is potentially a biomarker for the assessment of radiation-induced white matter injury

  15. Diffusion tensor tractography reveals muscle reconnection during axolotl limb regeneration.

    Directory of Open Access Journals (Sweden)

    Cheng-Han Wu

    Full Text Available Axolotls have amazing ability to regenerate their lost limbs. Our previous works showed that after amputation the remnant muscle ends remained at their original location whilst sending satellite cells into the regenerating parts to develop into early muscle fibers in the late differentiation stage. The parental and the newly formed muscle fibers were not connected until very late stage. The present study used non-invasive diffusion tensor imaging (DTI to monitor weekly axolotl upper arm muscles after amputation of their upper arms. DTI tractography showed that the regenerating muscle fibers became visible at 9-wpa (weeks post amputation, but a gap was observed between the regenerating and parental muscles. The gap was filled at 10-wpa, indicating reconnection of the fibers of both muscles. This was confirmed by histology. The DTI results indicate that 23% of the muscle fibers were reconnected at 10-wpa. In conclusion, DTI can be used to visualize axolotls' skeletal muscles and the results of muscle reconnection were in accordance with our previous findings. This non-invasive technique will allow researchers to identify the timeframe in which muscle fiber reconnection takes place and thus enable the study of the mechanisms underlying this reconnection.

  16. Shape anisotropy: tensor distance to anisotropy measure

    Science.gov (United States)

    Weldeselassie, Yonas T.; El-Hilo, Saba; Atkins, M. S.

    2011-03-01

    Fractional anisotropy, defined as the distance of a diffusion tensor from its closest isotropic tensor, has been extensively studied as quantitative anisotropy measure for diffusion tensor magnetic resonance images (DT-MRI). It has been used to reveal the white matter profile of brain images, as guiding feature for seeding and stopping in fiber tractography and for the diagnosis and assessment of degenerative brain diseases. Despite its extensive use in DT-MRI community, however, not much attention has been given to the mathematical correctness of its derivation from diffusion tensors which is achieved using Euclidean dot product in 9D space. But, recent progress in DT-MRI has shown that the space of diffusion tensors does not form a Euclidean vector space and thus Euclidean dot product is not appropriate for tensors. In this paper, we propose a novel and robust rotationally invariant diffusion anisotropy measure derived using the recently proposed Log-Euclidean and J-divergence tensor distance measures. An interesting finding of our work is that given a diffusion tensor, its closest isotropic tensor is different for different tensor distance metrics used. We demonstrate qualitatively that our new anisotropy measure reveals superior white matter profile of DT-MR brain images and analytically show that it has a higher signal to noise ratio than fractional anisotropy.

  17. A diffusion tensor imaging tractography algorithm based on Navier-Stokes fluid mechanics.

    Science.gov (United States)

    Hageman, Nathan S; Toga, Arthur W; Narr, Katherine L; Shattuck, David W

    2009-03-01

    We introduce a fluid mechanics based tractography method for estimating the most likely connection paths between points in diffusion tensor imaging (DTI) volumes. We customize the Navier-Stokes equations to include information from the diffusion tensor and simulate an artificial fluid flow through the DTI image volume. We then estimate the most likely connection paths between points in the DTI volume using a metric derived from the fluid velocity vector field. We validate our algorithm using digital DTI phantoms based on a helical shape. Our method segmented the structure of the phantom with less distortion than was produced using implementations of heat-based partial differential equation (PDE) and streamline based methods. In addition, our method was able to successfully segment divergent and crossing fiber geometries, closely following the ideal path through a digital helical phantom in the presence of multiple crossing tracts. To assess the performance of our algorithm on anatomical data, we applied our method to DTI volumes from normal human subjects. Our method produced paths that were consistent with both known anatomy and directionally encoded color images of the DTI dataset.

  18. Performances of diffusion kurtosis imaging and diffusion tensor imaging in detecting white matter abnormality in schizophrenia

    Directory of Open Access Journals (Sweden)

    Jiajia Zhu

    2015-01-01

    Full Text Available Diffusion kurtosis imaging (DKI is an extension of diffusion tensor imaging (DTI, exhibiting improved sensitivity and specificity in detecting developmental and pathological changes in neural tissues. However, little attention was paid to the performances of DKI and DTI in detecting white matter abnormality in schizophrenia. In this study, DKI and DTI were performed in 94 schizophrenia patients and 91 sex- and age-matched healthy controls. White matter integrity was assessed by fractional anisotropy (FA, mean diffusivity (MD, axial diffusivity (AD, radial diffusivity (RD, mean kurtosis (MK, axial kurtosis (AK and radial kurtosis (RK of DKI and FA, MD, AD and RD of DTI. Group differences in these parameters were compared using tract-based spatial statistics (TBSS (P  AK (20% > RK (3% and RD (37% > FA (24% > MD (21% for DKI, and RD (43% > FA (30% > MD (21% for DTI. DKI-derived diffusion parameters (RD, FA and MD were sensitive to detect abnormality in white matter regions (the corpus callosum and anterior limb of internal capsule with coherent fiber arrangement; however, the kurtosis parameters (MK and AK were sensitive to reveal abnormality in white matter regions (the juxtacortical white matter and corona radiata with complex fiber arrangement. In schizophrenia, the decreased AK suggests axonal damage; however, the increased RD indicates myelin impairment. These findings suggest that diffusion and kurtosis parameters could provide complementary information and they should be jointly used to reveal pathological changes in schizophrenia.

  19. Diffusion tensor analysis of corpus callosum in progressive supranuclear palsy

    International Nuclear Information System (INIS)

    Ito, Shoichi; Makino, Takahiro; Shirai, Wakako; Hattori, Takamichi

    2008-01-01

    Progressive supranuclear palsy (PSP) is a neurodegenerative disease featuring parkinsonism, supranuclear ophthalmoplegia, dysphagia, and frontal lobe dysfunction. The corpus callosum which consists of many commissure fibers probably reflects cerebral cortical function. Several previous reports showed atrophy or diffusion abnormalities of anterior corpus callosum in PSP patients, but partitioning method used in these studies was based on data obtained in nonhuman primates. In this study, we performed a diffusion tensor analysis using a new partitioning method for the human corpus callosum. Seven consecutive patients with PSP were compared with 29 age-matched patients with Parkinson's Disease (PD) and 19 age-matched healthy control subjects. All subjects underwent diffusion tensor magnetic resonance imaging, and the corpus callosum was partitioned into five areas on the mid-sagittal plane according to a recently established topography of human corpus callosum (CC1-prefrontal area, CC2-premotor and supplementary motor area, CC3-motor area, CC4-sensory area, CC5-parietal, temporal, and occipital area). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in each area and differences between groups were analyzed. In the PSP group, FA values were significantly decreased in CC1 and CC2, and ADC values were significantly increased in CC1 and CC2. Receiver operating characteristic analysis showed excellent reliability of FA and ADC analyses of CC1 for differentiating PSP from PD. The anterior corpus callosum corresponding to the prefrontal, premotor, and supplementary motor cortices is affected in PSP patients. This analysis can be an additional test for further confirmation of the diagnosis of PSP

  20. Diffusion tensor analysis of corpus callosum in progressive supranuclear palsy

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Shoichi; Makino, Takahiro; Shirai, Wakako; Hattori, Takamichi [Department of Neurology, Graduate School of Medicine, Chiba University (Japan)

    2008-11-15

    Progressive supranuclear palsy (PSP) is a neurodegenerative disease featuring parkinsonism, supranuclear ophthalmoplegia, dysphagia, and frontal lobe dysfunction. The corpus callosum which consists of many commissure fibers probably reflects cerebral cortical function. Several previous reports showed atrophy or diffusion abnormalities of anterior corpus callosum in PSP patients, but partitioning method used in these studies was based on data obtained in nonhuman primates. In this study, we performed a diffusion tensor analysis using a new partitioning method for the human corpus callosum. Seven consecutive patients with PSP were compared with 29 age-matched patients with Parkinson's Disease (PD) and 19 age-matched healthy control subjects. All subjects underwent diffusion tensor magnetic resonance imaging, and the corpus callosum was partitioned into five areas on the mid-sagittal plane according to a recently established topography of human corpus callosum (CC1-prefrontal area, CC2-premotor and supplementary motor area, CC3-motor area, CC4-sensory area, CC5-parietal, temporal, and occipital area). Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured in each area and differences between groups were analyzed. In the PSP group, FA values were significantly decreased in CC1 and CC2, and ADC values were significantly increased in CC1 and CC2. Receiver operating characteristic analysis showed excellent reliability of FA and ADC analyses of CC1 for differentiating PSP from PD. The anterior corpus callosum corresponding to the prefrontal, premotor, and supplementary motor cortices is affected in PSP patients. This analysis can be an additional test for further confirmation of the diagnosis of PSP.

  1. Extracting the diffusion tensor from molecular dynamics simulation with Milestoning

    International Nuclear Information System (INIS)

    Mugnai, Mauro L.; Elber, Ron

    2015-01-01

    We propose an algorithm to extract the diffusion tensor from Molecular Dynamics simulations with Milestoning. A Kramers-Moyal expansion of a discrete master equation, which is the Markovian limit of the Milestoning theory, determines the diffusion tensor. To test the algorithm, we analyze overdamped Langevin trajectories and recover a multidimensional Fokker-Planck equation. The recovery process determines the flux through a mesh and estimates local kinetic parameters. Rate coefficients are converted to the derivatives of the potential of mean force and to coordinate dependent diffusion tensor. We illustrate the computation on simple models and on an atomically detailed system—the diffusion along the backbone torsions of a solvated alanine dipeptide

  2. Voxel-based clustered imaging by multiparameter diffusion tensor images for glioma grading.

    Science.gov (United States)

    Inano, Rika; Oishi, Naoya; Kunieda, Takeharu; Arakawa, Yoshiki; Yamao, Yukihiro; Shibata, Sumiya; Kikuchi, Takayuki; Fukuyama, Hidenao; Miyamoto, Susumu

    2014-01-01

    Gliomas are the most common intra-axial primary brain tumour; therefore, predicting glioma grade would influence therapeutic strategies. Although several methods based on single or multiple parameters from diagnostic images exist, a definitive method for pre-operatively determining glioma grade remains unknown. We aimed to develop an unsupervised method using multiple parameters from pre-operative diffusion tensor images for obtaining a clustered image that could enable visual grading of gliomas. Fourteen patients with low-grade gliomas and 19 with high-grade gliomas underwent diffusion tensor imaging and three-dimensional T1-weighted magnetic resonance imaging before tumour resection. Seven features including diffusion-weighted imaging, fractional anisotropy, first eigenvalue, second eigenvalue, third eigenvalue, mean diffusivity and raw T2 signal with no diffusion weighting, were extracted as multiple parameters from diffusion tensor imaging. We developed a two-level clustering approach for a self-organizing map followed by the K-means algorithm to enable unsupervised clustering of a large number of input vectors with the seven features for the whole brain. The vectors were grouped by the self-organizing map as protoclusters, which were classified into the smaller number of clusters by K-means to make a voxel-based diffusion tensor-based clustered image. Furthermore, we also determined if the diffusion tensor-based clustered image was really helpful for predicting pre-operative glioma grade in a supervised manner. The ratio of each class in the diffusion tensor-based clustered images was calculated from the regions of interest manually traced on the diffusion tensor imaging space, and the common logarithmic ratio scales were calculated. We then applied support vector machine as a classifier for distinguishing between low- and high-grade gliomas. Consequently, the sensitivity, specificity, accuracy and area under the curve of receiver operating characteristic

  3. Combined Tensor Fitting and TV Regularization in Diffusion Tensor Imaging Based on a Riemannian Manifold Approach.

    Science.gov (United States)

    Baust, Maximilian; Weinmann, Andreas; Wieczorek, Matthias; Lasser, Tobias; Storath, Martin; Navab, Nassir

    2016-08-01

    In this paper, we consider combined TV denoising and diffusion tensor fitting in DTI using the affine-invariant Riemannian metric on the space of diffusion tensors. Instead of first fitting the diffusion tensors, and then denoising them, we define a suitable TV type energy functional which incorporates the measured DWIs (using an inverse problem setup) and which measures the nearness of neighboring tensors in the manifold. To approach this functional, we propose generalized forward- backward splitting algorithms which combine an explicit and several implicit steps performed on a decomposition of the functional. We validate the performance of the derived algorithms on synthetic and real DTI data. In particular, we work on real 3D data. To our knowledge, the present paper describes the first approach to TV regularization in a combined manifold and inverse problem setup.

  4. Principles and implementation of diffusion-weighted and diffusion tensor imaging

    International Nuclear Information System (INIS)

    Roberts, Timothy P.L.; Schwartz, E.S.

    2007-01-01

    We review the physiological basis of diffusion-weighted imaging and discuss the implementation of diffusion-weighted imaging pulse sequences and the subsequent postprocessing to yield quantitative estimations of diffusion parameters. We also introduce the concept of directionality of ''apparent'' diffusion in vivo and the means of assessing such anisotropy quantitatively. This in turn leads to the methodological application of diffusion tensor imaging and the subsequent postprocessing, known as tractography. The following articles deal with the clinical applications enabled by such methodologies. (orig.)

  5. Tensor Based Representation and Analysis of Diffusion-Weighted Magnetic Resonance Images

    Science.gov (United States)

    Barmpoutis, Angelos

    2009-01-01

    Cartesian tensor bases have been widely used to model spherical functions. In medical imaging, tensors of various orders can approximate the diffusivity function at each voxel of a diffusion-weighted MRI data set. This approximation produces tensor-valued datasets that contain information about the underlying local structure of the scanned tissue.…

  6. Outcomes of Diffusion Tensor Tractography-Integrated Stereotactic Radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Koga, Tomoyuki, E-mail: kouga-tky@umin.ac.jp [Department of Neurosurgery, University of Tokyo Hospital, Tokyo (Japan); Maruyama, Keisuke; Kamada, Kyousuke; Ota, Takahiro; Shin, Masahiro [Department of Neurosurgery, University of Tokyo Hospital, Tokyo (Japan); Itoh, Daisuke [Department of Radiology, University of Tokyo Hospital, Tokyo (Japan); Kunii, Naoto [Department of Neurosurgery, University of Tokyo Hospital, Tokyo (Japan); Ino, Kenji; Terahara, Atsuro; Aoki, Shigeki; Masutani, Yoshitaka [Department of Radiology, University of Tokyo Hospital, Tokyo (Japan); Saito, Nobuhito [Department of Neurosurgery, University of Tokyo Hospital, Tokyo (Japan)

    2012-02-01

    Purpose: To analyze the effect of use of tractography of the critical brain white matter fibers created from diffusion tensor magnetic resonance imaging on reduction of morbidity associated with radiosurgery. Methods and Materials: Tractography of the pyramidal tract has been integrated since February 2004 if lesions are adjacent to it, the optic radiation since May 2006, and the arcuate fasciculus since October 2007. By visually confirming the precise location of these fibers, the dose to these fiber tracts was optimized. One hundred forty-four consecutive patients with cerebral arteriovenous malformations who underwent radiosurgery with this technique between February 2004 and December 2009 were analyzed. Results: Tractography was prospectively integrated in 71 of 155 treatments for 144 patients. The pyramidal tract was visualized in 45, the optic radiation in 22, and the arcuate fasciculus in 13 (two tracts in 9). During the follow-up period of 3 to 72 months (median, 23 months) after the procedure, 1 patient showed permanent worsening of pre-existing dysesthesia, and another patient exhibited mild transient hemiparesis 12 months later but fully recovered after oral administration of corticosteroid agents. Two patients had transient speech disturbance before starting integration of the arcuate fasciculus tractography, but no patient thereafter. Conclusion: Integrating tractography helped prevent morbidity of radiosurgery in patients with brain arteriovenous malformations.

  7. Imaging Arterial Fibres Using Diffusion Tensor Imaging—Feasibility Study and Preliminary Results

    Directory of Open Access Journals (Sweden)

    Ciaran K. Simms

    2010-01-01

    Full Text Available MR diffusion tensor imaging (DTI was used to analyze the fibrous structure of aortic tissue. A fresh porcine aorta was imaged at 7T using a spin echo sequence with the following parameters: matrix 128 × 128 pixel; slice thickness 0.5 mm; interslice spacing 0.1 mm; number of slices 16; echo time 20.3 s; field of view 28 mm × 28 mm. Eigenvectors from the diffusion tensor images were calculated for the central image slice and the averaged tensors and the eigenvector corresponding to the largest eigenvalue showed two distinct angles corresponding to near 0∘ and 180∘ to the transverse plane of the aorta. Fibre tractography within the aortic volume imaged confirmed that fibre angles were oriented helically with lead angles of 15±2.5∘ and 175±2.5∘. The findings correspond to current histological and microscopy data on the fibrous structure of aortic tissue, and therefore the eigenvector maps and fibre tractography appear to reflect the alignment of the fibers in the aorta. In view of current efforts to develop noninvasive diagnostic tools for cardiovascular diseases, DTI may offer a technique to assess the structural properties of arterial tissue and hence any changes or degradation in arterial tissue.

  8. Adaptive distance learning scheme for diffusion tensor imaging using kernel target alignment

    NARCIS (Netherlands)

    Rodrigues, P.R.; Vilanova, A.; Twellmann, T.; Haar Romenij, ter B.M.; Alexander, D.; Gee, J.; Whitaker, R.

    2008-01-01

    In segmentation techniques for Diffusion Tensor Imaging (DTI) data, the similarity of diffusion tensors must be assessed for partitioning data into regions which are homogeneous in terms of tensor characteristics. Various distance measures have been proposed in literature for analysing the

  9. Oculomotor nerve palsy evaluated by diffusion-tensor tractography

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, Kei; Kizu, Osamu; Ito, Hirotoshi; Nishimura, Tsunehiko [Kyoto Prefectural University of Medicine, Department of Radiology, Kyoto (Japan); Shiga, Kensuke; Akiyama, Katsuhisa; Nakagawa, Masanori [Kyoto Prefectural University of Medicine, Department of Neurology, Kyoto (Japan)

    2006-06-15

    The aim of the study was to test the feasibility of the tractography technique based on diffusion-tensor imaging (DTI) for the assessment of small infarcts involving the brainstem. A patient who presented with an isolated left third cranial nerve palsy underwent magnetic resonance examination. Images were obtained by use of a whole-body, 1.5-T imager. Data were transferred to an off-line workstation for fiber tracking. The conventional diffusion-weighted imaging (DWI) performed using a 5 mm slice thickness could only depict an equivocal hyperintensity lesion located at the left paramedian midbrain. An additional thin-slice DTI was performed immediately after the initial DWI using a 3 mm slice thickness and was able to delineate the lesion more clearly. Image postprocessing of thin-slice DTI data revealed that the lesion location involved the course of the third cranial nerve tract, corresponding with the patient's clinical symptoms. The tractography technique can be applied to assess fine neuronal structures of the brainstem, enabling direct clinicoradiological correlation of small infarcts involving this region. (orig.)

  10. Oculomotor nerve palsy evaluated by diffusion-tensor tractography

    International Nuclear Information System (INIS)

    Yamada, Kei; Kizu, Osamu; Ito, Hirotoshi; Nishimura, Tsunehiko; Shiga, Kensuke; Akiyama, Katsuhisa; Nakagawa, Masanori

    2006-01-01

    The aim of the study was to test the feasibility of the tractography technique based on diffusion-tensor imaging (DTI) for the assessment of small infarcts involving the brainstem. A patient who presented with an isolated left third cranial nerve palsy underwent magnetic resonance examination. Images were obtained by use of a whole-body, 1.5-T imager. Data were transferred to an off-line workstation for fiber tracking. The conventional diffusion-weighted imaging (DWI) performed using a 5 mm slice thickness could only depict an equivocal hyperintensity lesion located at the left paramedian midbrain. An additional thin-slice DTI was performed immediately after the initial DWI using a 3 mm slice thickness and was able to delineate the lesion more clearly. Image postprocessing of thin-slice DTI data revealed that the lesion location involved the course of the third cranial nerve tract, corresponding with the patient's clinical symptoms. The tractography technique can be applied to assess fine neuronal structures of the brainstem, enabling direct clinicoradiological correlation of small infarcts involving this region. (orig.)

  11. Anisotropic conductivity tensor imaging in MREIT using directional diffusion rate of water molecules

    International Nuclear Information System (INIS)

    Kwon, Oh In; Jeong, Woo Chul; Sajib, Saurav Z K; Kim, Hyung Joong; Woo, Eung Je

    2014-01-01

    Magnetic resonance electrical impedance tomography (MREIT) is an emerging method to visualize electrical conductivity and/or current density images at low frequencies (below 1 KHz). Injecting currents into an imaging object, one component of the induced magnetic flux density is acquired using an MRI scanner for isotropic conductivity image reconstructions. Diffusion tensor MRI (DT-MRI) measures the intrinsic three-dimensional diffusion property of water molecules within a tissue. It characterizes the anisotropic water transport by the effective diffusion tensor. Combining the DT-MRI and MREIT techniques, we propose a novel direct method for absolute conductivity tensor image reconstructions based on a linear relationship between the water diffusion tensor and the electrical conductivity tensor. We first recover the projected current density, which is the best approximation of the internal current density one can obtain from the measured single component of the induced magnetic flux density. This enables us to estimate a scale factor between the diffusion tensor and the conductivity tensor. Combining these values at all pixels with the acquired diffusion tensor map, we can quantitatively recover the anisotropic conductivity tensor map. From numerical simulations and experimental verifications using a biological tissue phantom, we found that the new method overcomes the limitations of each method and successfully reconstructs both the direction and magnitude of the conductivity tensor for both the anisotropic and isotropic regions. (paper)

  12. White matter microstructure in transsexuals and controls investigated by diffusion tensor imaging.

    Science.gov (United States)

    Kranz, Georg S; Hahn, Andreas; Kaufmann, Ulrike; Küblböck, Martin; Hummer, Allan; Ganger, Sebastian; Seiger, Rene; Winkler, Dietmar; Swaab, Dick F; Windischberger, Christian; Kasper, Siegfried; Lanzenberger, Rupert

    2014-11-12

    Biological causes underpinning the well known gender dimorphisms in human behavior, cognition, and emotion have received increased attention in recent years. The advent of diffusion-weighted magnetic resonance imaging has permitted the investigation of the white matter microstructure in unprecedented detail. Here, we aimed to study the potential influences of biological sex, gender identity, sex hormones, and sexual orientation on white matter microstructure by investigating transsexuals and healthy controls using diffusion tensor imaging (DTI). Twenty-three female-to-male (FtM) and 21 male-to-female (MtF) transsexuals, as well as 23 female (FC) and 22 male (MC) controls underwent DTI at 3 tesla. Fractional anisotropy, axial, radial, and mean diffusivity were calculated using tract-based spatial statistics (TBSS) and fiber tractography. Results showed widespread significant differences in mean diffusivity between groups in almost all white matter tracts. FCs had highest mean diffusivities, followed by FtM transsexuals with lower values, MtF transsexuals with further reduced values, and MCs with lowest values. Investigating axial and radial diffusivities showed that a transition in axial diffusivity accounted for mean diffusivity results. No significant differences in fractional anisotropy maps were found between groups. Plasma testosterone levels were strongly correlated with mean, axial, and radial diffusivities. However, controlling for individual estradiol, testosterone, or progesterone plasma levels or for subjects' sexual orientation did not change group differences. Our data harmonize with the hypothesis that fiber tract development is influenced by the hormonal environment during late prenatal and early postnatal brain development. Copyright © 2014 the authors 0270-6474/14/3415466-10$15.00/0.

  13. White Matter Microstructure in Transsexuals and Controls Investigated by Diffusion Tensor Imaging

    Science.gov (United States)

    Kranz, Georg S.; Hahn, Andreas; Kaufmann, Ulrike; Küblböck, Martin; Hummer, Allan; Ganger, Sebastian; Seiger, Rene; Winkler, Dietmar; Swaab, Dick F.; Windischberger, Christian; Kasper, Siegfried; Lanzenberger, Rupert

    2015-01-01

    Biological causes underpinning the well known gender dimorphisms in human behavior, cognition, and emotion have received increased attention in recent years. The advent of diffusion-weighted magnetic resonance imaging has permitted the investigation of the white matter microstructure in unprecedented detail. Here, we aimed to study the potential influences of biological sex, gender identity, sex hormones, and sexual orientation on white matter microstructure by investigating transsexuals and healthy controls using diffusion tensor imaging (DTI). Twenty-three female-to-male (FtM) and 21 male-to-female (MtF) transsexuals, as well as 23 female (FC) and 22 male (MC) controls underwent DTI at 3 tesla. Fractional anisotropy, axial, radial, and mean diffusivity were calculated using tract-based spatial statistics (TBSS) and fiber tractography. Results showed widespread significant differences in mean diffusivity between groups in almost all white matter tracts. FCs had highest mean diffusivities, followed by FtM transsexuals with lower values, MtF transsexuals with further reduced values, and MCs with lowest values. Investigating axial and radial diffusivities showed that a transition in axial diffusivity accounted for mean diffusivity results. No significant differences in fractional anisotropy maps were found between groups. Plasma testosterone levels were strongly correlated with mean, axial, and radial diffusivities. However, controlling for individual estradiol, testosterone, or progesterone plasma levels or for subjects’ sexual orientation did not change group differences. Our data harmonize with the hypothesis that fiber tract development is influenced by the hormonal environment during late prenatal and early postnatal brain development. PMID:25392513

  14. Review of diffusion tensor imaging and its application in children

    Energy Technology Data Exchange (ETDEWEB)

    Vorona, Gregory A. [Children' s Hospital of Richmond at Virginia Commonwealth University, Department of Radiology, Richmond, VA (United States); Berman, Jeffrey I. [Children' s Hospital of Philadelphia, Department of Radiology, Philadelphia, PA (United States)

    2015-09-15

    Diffusion MRI is an imaging technique that uses the random motion of water to probe tissue microstructure. Diffusion tensor imaging (DTI) can quantitatively depict the organization and connectivity of white matter. Given the non-invasiveness of the technique, DTI has become a widely used tool for researchers and clinicians to examine the white matter of children. This review covers the basics of diffusion-weighted imaging and diffusion tensor imaging and discusses examples of their clinical application in children. (orig.)

  15. Diffusion tensor imaging of the human calf: Variation of inter- and intramuscle-specific diffusion parameters.

    Science.gov (United States)

    Schlaffke, Lara; Rehmann, Robert; Froeling, Martijn; Kley, Rudolf; Tegenthoff, Martin; Vorgerd, Matthias; Schmidt-Wilcke, Tobias

    2017-10-01

    To investigate to what extent inter- and intramuscular variations of diffusion parameters of human calf muscles can be explained by age, gender, muscle location, and body mass index (BMI) in a specific age group (20-35 years). Whole calf muscles of 18 healthy volunteers were evaluated. Magnetic resonance imaging (MRI) was performed using a 3T scanner and a 16-channel Torso XL coil. Diffusion-weighted images were acquired to perform fiber tractography and diffusion tensor imaging (DTI) analysis for each muscle of both legs. Fiber tractography was used to separate seven lower leg muscles. Associations between DTI parameters and confounds were evaluated. All muscles were additionally separated in seven identical segments along the z-axis to evaluate intramuscular differences in diffusion parameters. Fractional anisotropy (FA) and mean diffusivity (MD) were obtained for each muscle with low standard deviations (SDs) (SD FA : 0.01-0.02; SD MD : 0.07-0.14(10 -3 )). We found significant differences in FA values of the tibialis anterior muscle (AT) and extensor digitorum longus (EDL) muscles between men and women for whole muscle FA (two-sample t-tests; AT: P = 0.0014; EDL: P = 0.0004). We showed significant intramuscular differences in diffusion parameters between adjacent segments in most calf muscles (P < 0.001). Whereas muscle insertions showed higher (SD 0.03-0.06) than muscle bellies (SD 0.01-0.03), no relationships between FA or MD with age or BMI were found. Inter- and intramuscular variations in diffusion parameters of the calf were shown, which are not related to age or BMI in this age group. Differences between muscle belly and insertion should be considered when interpreting datasets not including whole muscles. 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1137-1148. © 2017 International Society for Magnetic Resonance in Medicine.

  16. A GENERALIZED DIFFUSION TENSOR FOR FULLY ANISOTROPIC DIFFUSION OF ENERGETIC PARTICLES IN THE HELIOSPHERIC MAGNETIC FIELD

    International Nuclear Information System (INIS)

    Effenberger, F.; Fichtner, H.; Scherer, K.; Barra, S.; Kleimann, J.; Strauss, R. D.

    2012-01-01

    The spatial diffusion of cosmic rays in turbulent magnetic fields can, in the most general case, be fully anisotropic, i.e., one has to distinguish three diffusion axes in a local, field-aligned frame. We reexamine the transformation for the diffusion tensor from this local to a global frame, in which the Parker transport equation for energetic particles is usually formulated and solved. Particularly, we generalize the transformation formulae to allow for an explicit choice of two principal local perpendicular diffusion axes. This generalization includes the 'traditional' diffusion tensor in the special case of isotropic perpendicular diffusion. For the local frame, we describe the motivation for the choice of the Frenet-Serret trihedron, which is related to the intrinsic magnetic field geometry. We directly compare the old and the new tensor elements for two heliospheric magnetic field configurations, namely the hybrid Fisk and Parker fields. Subsequently, we examine the significance of the different formulations for the diffusion tensor in a standard three-dimensional model for the modulation of galactic protons. For this, we utilize a numerical code to evaluate a system of stochastic differential equations equivalent to the Parker transport equation and present the resulting modulated spectra. The computed differential fluxes based on the new tensor formulation deviate from those obtained with the 'traditional' one (only valid for isotropic perpendicular diffusion) by up to 60% for energies below a few hundred MeV depending on heliocentric distance.

  17. Diffusion tensor tractography of the brainstem pyramidal tract; A study on the optimal reduction factor in parallel imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Yun Jung; Park, Jong Bin; Kim, Jae Hyoung; Choi, Byung Se; Jung, Cheol Kyu [Dept. of of Radiology, Seoul National University College of Medicine, Seoul National University Bundang Hospital, Seongnam (Korea, Republic of)

    2016-08-15

    Parallel imaging mitigates susceptibility artifacts that can adversely affect diffusion tensor tractography (DTT) of the pons depending on the reduction (R) factor. We aimed to find the optimal R factor for DTT of the pons that would allow us to visualize the largest possible number of pyramidal tract fibers. Diffusion tensor imaging was performed on 10 healthy subjects at 3 Tesla based on single-shot echo-planar imaging using the following parameters: b value, 1000 s/mm{sup 2}; gradient direction, 15; voxel size, 2 × 2 × 2 mm{sup 3}; and R factors, 1, 2, 3, 4, and 5. DTT of the right and left pyramidal tracts in the pons was conducted in all subjects. Signal-to-noise ratio (SNR), image distortion, and the number of fibers in the tracts were compared across R factors. SNR, image distortion, and fiber number were significantly different according to R factor. Maximal SNR was achieved with an R factor of 2. Image distortion was minimal with an R factor of 5. The number of visible fibers was greatest with an R factor of 3. R factor 3 is optimal for DTT of the pontine pyramidal tract. A balanced consideration of SNR and image distortion, which do not have the same dependence on the R factor, is necessary for DTT of the pons.

  18. Tract-specific analysis of white matter pathways in healthy subjects: a pilot study using diffusion tensor MRI

    Energy Technology Data Exchange (ETDEWEB)

    Yasmin, Hasina; Abe, Osamu; Nakata, Yasuhiro; Hayashi, Naoto; Masutani, Yoshitaka; Goto, Masami; Ohtomo, Kuni [University of Tokyo, Department of Radiology, Bunkyo-ku, Tokyo (Japan); Aoki, Shigeki [Juntendo University, Department of Radiology, Bunkyo-ku, Tokyo (Japan)

    2009-12-15

    To date, very scant data is available regarding normal diffusion properties of white matter (WM) fibers. The present study aimed to initiate the establishment of a database of normal diffusion tensor metrics of cerebral WM fibers, including the uncinate fasciculus (UF), posterior cingulum (PC), fornix, and corticospinal tract (CST) for healthy adults using tract-specific analysis by diffusion tensor tractography (DTT). We also attempted to clarify whether age and laterality exerted any effects on this study group. DTT of WM fibers were generated for 100 healthy subjects, then mean diffusivity (MD) and fractional anisotropy (FA) of the tracts were measured. Pearson correlation analysis was used to evaluate age relationships. Paired t testing was used to compare hemispheric asymmetry. Interobserver correlation tests were also performed. Our results showed FA values for UF (right, 0.42 {+-} 0.03; left, 0.40{+-}0.03), PC (0.51 {+-} 0.06, 0.52 {+-} 0.06), fornix (0.37 {+-} 0.06, 0.38 {+-} 0.06), CST (0.70 {+-} 0.06, 0.69 {+-} 0.07), and MD values for UF (0.81 {+-} 0.03, 0.82 {+-} 0.04), PC (0.72 {+-} 0.03, 0.72 {+-} 0.04), fornix (1.86 {+-} 0.32, 1.94 {+-} 0.37), and CST (0.72 {+-} 0.03, 0.74 {+-} 0.04). We identified a significant positive correlation between age and MD in the right UF and bilateral fornices, and a negative correlation between age and FA in bilateral fornices. Hemispheric asymmetry was observed in FA of UF (right > left) and MD of CST (left > right). The results constitute a normative dataset for diffusion parameters of four WM tracts that can be used to identify, characterize, and establish the significance of changes in diseases affecting specific tracts. (orig.)

  19. Diffusion tensor and diffusion weighted imaging. Pictorial mathematics

    Energy Technology Data Exchange (ETDEWEB)

    Nakada, Tsutomu [California Univ., Davis, CA (United States)

    1995-06-01

    A new imaging algorithm for the treatment of a second order apparent diffusion tensor, D{sub app}{sup {xi}} is described. The method calls for only mathematics of images (pictorial mathematics) without necessity of eigenvalues/eigenvectors estimation. Nevertheless, it is capable of extracting properties of D{sub app}{sup {xi}} invariant to observation axes. While trace image is an example of images weighted by invariance of the tensor matrix, three dimensional anisotropy (3DAC) contrast represents the imaging method making use to anisotropic direction of tensor ellipsoid producing color coded contrast of exceptionally high anatomic resolution. Contrary to intuition, the processes require only a simple algorithm directly applicable to clinical magnetic resonance imaging (MRI). As a contrast method which precisely represents physical characteristics of a target tissue, invariant D{sub app}{sup {xi}} images produced by pictorial mathematics possess significant potential for a number of biological and clinical applications. (author).

  20. Preliminary diffusion tensor imaging studies in limb-girdle muscular dystrophies

    Science.gov (United States)

    Hidalgo-Tobon, S.; Hernandez-Salazar, G.; Vargas-Cañas, S.; Marrufo-Melendez, O.; Solis-Najera, S.; Taboada-Barajas, J.; Rodriguez, A. O.; Delgado-Hernandez, R.

    2012-10-01

    Limb-girdle muscular dystrophies (LGMD) are a group of autosomal dominantly or recessively inherited muscular dystrophies that also present with primary proximal (limb-girdle) muscle weakness. This type of dystrophy involves the shoulder and pelvic girdles, distinct phenotypic or clinical characteristics are recognized. Imaging experiments were conducted on a 1.5T GE scanner (General Electric Medical Systems. Milwaukee. USA), using a combination of two eight-channel coil array. Diffusion Tensor Imaging (DTI) data were acquired using a SE-EPI sequence, diffusion weighted gradients were applied along 30 non-collinear directions with a b-value=550 s/mm2. The connective tissue content does not appear to have a significant effect on the directionality of the diffusion, as assessed by fractional anisotropy. The fibers of the Sartorius muscle and gracilis showed decreased number of tracts, secondary to fatty infiltration and replacement of connective tissue and muscle mass loss characteristic of the underlying pathology. Our results demonstrated the utility of non-invasive MRI techniques to characterize the muscle pathology, through quantitative and qualitative methods such as the FA values and tractrography.

  1. Assessment of damage to cerebral white matter fiber in the subacute phase after carbon monoxide poisoning using fractional anisotropy in diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Beppu, Takaaki [Iwate Medical University, Departments of Neurosurgery, Morioka (Japan); Iwate Medical University, Department of Hyperbaric Medicine, Morioka (Japan); Nishimoto, Hideaki; Ishigaki, Daiya [Iwate Medical University, Departments of Neurosurgery, Morioka (Japan); Iwate Medical University, Advanced Medical Research Center, Morioka (Japan); Fujiwara, Shunrou; Sasaki, Makoto [Iwate Medical University, Advanced Medical Research Center, Morioka (Japan); Yoshida, Tomoyuki [Iwate Medical University, Department of Psychiatry, Morioka (Japan); Oikawa, Hirotaka [Iwate Prefectural Advanced Critical Care and Emergency, Morioka (Japan); Kamada, Katsura [Iwate Medical University, Department of Hyperbaric Medicine, Morioka (Japan); Ogasawara, Kuniaki [Iwate Medical University, Departments of Neurosurgery, Morioka (Japan)

    2010-08-15

    Chronic neuropsychiatric symptoms after carbon monoxide (CO) poisoning are caused by demyelination of cerebral white matter fibers. We examined whether diffusion tensor imaging can sensitively represent damage to fibers of the centrum semiovale in the subacute phase after CO intoxication. Subjects comprised 13 adult patients with CO poisoning, classified into three groups according to clinical behaviors: group A, patients with transit acute symptoms only; group P, patients with persistent neurological symptoms; and group D, patients with ''delayed neuropsychiatric sequelae'' occurring after a lucid interval. Median fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the centrum semiovale bilaterally at 2 weeks were compared between these groups and a control group of ten healthy volunteers. Myelin basic protein (MBP) concentration in cerebrospinal fluid was examined at 2 weeks to evaluate the degree of demyelination in patients. MBP concentration was abnormal or detectable for all group P and group D patients but was undetectable for all patients assigned to group A. Low FA values in groups P and D displaying chronic neurological symptoms clearly differed from those in controls and group A without chronic neurological symptoms, but ADC showed no significant differences between patient groups. MBP concentration at 2 weeks after CO inhalation confirmed a certain extent of demyelination in the central nervous system of patients who would develop chronic neurological symptoms. In these patients, FA sensitively represented damage to white matter fibers in the centrum semiovale in the subacute phase after CO intoxication. (orig.)

  2. Assessment of damage to cerebral white matter fiber in the subacute phase after carbon monoxide poisoning using fractional anisotropy in diffusion tensor imaging

    International Nuclear Information System (INIS)

    Beppu, Takaaki; Nishimoto, Hideaki; Ishigaki, Daiya; Fujiwara, Shunrou; Sasaki, Makoto; Yoshida, Tomoyuki; Oikawa, Hirotaka; Kamada, Katsura; Ogasawara, Kuniaki

    2010-01-01

    Chronic neuropsychiatric symptoms after carbon monoxide (CO) poisoning are caused by demyelination of cerebral white matter fibers. We examined whether diffusion tensor imaging can sensitively represent damage to fibers of the centrum semiovale in the subacute phase after CO intoxication. Subjects comprised 13 adult patients with CO poisoning, classified into three groups according to clinical behaviors: group A, patients with transit acute symptoms only; group P, patients with persistent neurological symptoms; and group D, patients with ''delayed neuropsychiatric sequelae'' occurring after a lucid interval. Median fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the centrum semiovale bilaterally at 2 weeks were compared between these groups and a control group of ten healthy volunteers. Myelin basic protein (MBP) concentration in cerebrospinal fluid was examined at 2 weeks to evaluate the degree of demyelination in patients. MBP concentration was abnormal or detectable for all group P and group D patients but was undetectable for all patients assigned to group A. Low FA values in groups P and D displaying chronic neurological symptoms clearly differed from those in controls and group A without chronic neurological symptoms, but ADC showed no significant differences between patient groups. MBP concentration at 2 weeks after CO inhalation confirmed a certain extent of demyelination in the central nervous system of patients who would develop chronic neurological symptoms. In these patients, FA sensitively represented damage to white matter fibers in the centrum semiovale in the subacute phase after CO intoxication. (orig.)

  3. Evaluation of diffusion-tensor imaging-based global search and tractography for tumor surgery close to the language system.

    Directory of Open Access Journals (Sweden)

    Mirco Richter

    Full Text Available Pre-operative planning and intra-operative guidance in neurosurgery require detailed information about the location of functional areas and their anatomo-functional connectivity. In particular, regarding the language system, post-operative deficits such as aphasia can be avoided. By combining functional magnetic resonance imaging and diffusion tensor imaging, the connectivity between functional areas can be reconstructed by tractography techniques that need to cope with limitations such as limited resolution and low anisotropic diffusion close to functional areas. Tumors pose particular challenges because of edema, displacement effects on brain tissue and infiltration of white matter. Under these conditions, standard fiber tracking methods reconstruct pathways of insufficient quality. Therefore, robust global or probabilistic approaches are required. In this study, two commonly used standard fiber tracking algorithms, streamline propagation and tensor deflection, were compared with a previously published global search, Gibbs tracking and a connection-oriented probabilistic tractography approach. All methods were applied to reconstruct neuronal pathways of the language system of patients undergoing brain tumor surgery, and control subjects. Connections between Broca and Wernicke areas via the arcuate fasciculus (AF and the inferior fronto-occipital fasciculus (IFOF were validated by a clinical expert to ensure anatomical feasibility, and compared using distance- and diffusion-based similarity metrics to evaluate their agreement on pathway locations. For both patients and controls, a strong agreement between all methods was observed regarding the location of the AF. In case of the IFOF however, standard fiber tracking and Gibbs tracking predominantly identified the inferior longitudinal fasciculus that plays a secondary role in semantic language processing. In contrast, global search resolved connections in almost every case via the IFOF which

  4. Joint eigenvector estimation from mutually anisotropic tensors improves susceptibility tensor imaging of the brain, kidney, and heart.

    Science.gov (United States)

    Dibb, Russell; Liu, Chunlei

    2017-06-01

    To develop a susceptibility-based MRI technique for probing microstructure and fiber architecture of magnetically anisotropic tissues-such as central nervous system white matter, renal tubules, and myocardial fibers-in three dimensions using susceptibility tensor imaging (STI) tools. STI can probe tissue microstructure, but is limited by reconstruction artifacts because of absent phase information outside the tissue and noise. STI accuracy may be improved by estimating a joint eigenvector from mutually anisotropic susceptibility and relaxation tensors. Gradient-recalled echo image data were simulated using a numerical phantom and acquired from the ex vivo mouse brain, kidney, and heart. Susceptibility tensor data were reconstructed using STI, regularized STI, and the proposed algorithm of mutually anisotropic and joint eigenvector STI (MAJESTI). Fiber map and tractography results from each technique were compared with diffusion tensor data. MAJESTI reduced the estimated susceptibility tensor orientation error by 30% in the phantom, 36% in brain white matter, 40% in the inner medulla of the kidney, and 45% in myocardium. This improved the continuity and consistency of susceptibility-based fiber tractography in each tissue. MAJESTI estimation of the susceptibility tensors yields lower orientation errors for susceptibility-based fiber mapping and tractography in the intact brain, kidney, and heart. Magn Reson Med 77:2331-2346, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  5. Differences in Gaussian diffusion tensor imaging and non-Gaussian diffusion kurtosis imaging model-based estimates of diffusion tensor invariants in the human brain.

    Science.gov (United States)

    Lanzafame, S; Giannelli, M; Garaci, F; Floris, R; Duggento, A; Guerrisi, M; Toschi, N

    2016-05-01

    An increasing number of studies have aimed to compare diffusion tensor imaging (DTI)-related parameters [e.g., mean diffusivity (MD), fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (AD)] to complementary new indexes [e.g., mean kurtosis (MK)/radial kurtosis (RK)/axial kurtosis (AK)] derived through diffusion kurtosis imaging (DKI) in terms of their discriminative potential about tissue disease-related microstructural alterations. Given that the DTI and DKI models provide conceptually and quantitatively different estimates of the diffusion tensor, which can also depend on fitting routine, the aim of this study was to investigate model- and algorithm-dependent differences in MD/FA/RD/AD and anisotropy mode (MO) estimates in diffusion-weighted imaging of human brain white matter. The authors employed (a) data collected from 33 healthy subjects (20-59 yr, F: 15, M: 18) within the Human Connectome Project (HCP) on a customized 3 T scanner, and (b) data from 34 healthy subjects (26-61 yr, F: 5, M: 29) acquired on a clinical 3 T scanner. The DTI model was fitted to b-value =0 and b-value =1000 s/mm(2) data while the DKI model was fitted to data comprising b-value =0, 1000 and 3000/2500 s/mm(2) [for dataset (a)/(b), respectively] through nonlinear and weighted linear least squares algorithms. In addition to MK/RK/AK maps, MD/FA/MO/RD/AD maps were estimated from both models and both algorithms. Using tract-based spatial statistics, the authors tested the null hypothesis of zero difference between the two MD/FA/MO/RD/AD estimates in brain white matter for both datasets and both algorithms. DKI-derived MD/FA/RD/AD and MO estimates were significantly higher and lower, respectively, than corresponding DTI-derived estimates. All voxelwise differences extended over most of the white matter skeleton. Fractional differences between the two estimates [(DKI - DTI)/DTI] of most invariants were seen to vary with the invariant value itself as well as with MK

  6. Analysis of normal-appearing white matter of multiple sclerosis by tensor-based two-compartment model of water diffusion

    International Nuclear Information System (INIS)

    Tachibana, Yasuhiko; Obata, Takayuki; Yoshida, Mariko; Hori, Masaaki; Kamagata, Koji; Suzuki, Michimasa; Fukunaga, Issei; Kamiya, Kouhei; Aoki, Shigeki; Yokoyama, Kazumasa; Hattori, Nobutaka; Inoue, Tomio

    2015-01-01

    To compare the significance of the two-compartment model, considering diffusional anisotropy with conventional diffusion analyzing methods regarding the detection of occult changes in normal-appearing white matter (NAWM) of multiple sclerosis (MS). Diffusion-weighted images (nine b-values with six directions) were acquired from 12 healthy female volunteers (22-52 years old, median 33 years) and 13 female MS patients (24-48 years old, median 37 years). Diffusion parameters based on the two-compartment model of water diffusion considering diffusional anisotropy was calculated by a proposed method. Other parameters including diffusion tensor imaging and conventional apparent diffusion coefficient (ADC) were also obtained. They were compared statistically between the control and MS groups. Diffusion of the slow diffusion compartment in the radial direction of neuron fibers was elevated in MS patients (0.121 x 10 -3 mm 2 /s) in comparison to control (0.100 x 10 -3 mm 2 /s), the difference being significant (P = 0.001). The difference between the groups was not significant in other comparisons, including conventional ADC and fractional anisotropy (FA) of diffusion tensor imaging. The proposed method was applicable to clinically acceptable small data. The parameters obtained by this method improved the detectability of occult changes in NAWM compared to the conventional methods. (orig.)

  7. Analysis of normal-appearing white matter of multiple sclerosis by tensor-based two-compartment model of water diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Tachibana, Yasuhiko [National Institute of Radiological Sciences, Research Center for Charged Particle Therapy, Chiba (Japan); Yokohama City University Graduate School of Medicine, Department of Radiology, Yokohama (Japan); Juntendo University School of Medicine, Department of Radiology, Tokyo (Japan); Obata, Takayuki [National Institute of Radiological Sciences, Research Center for Charged Particle Therapy, Chiba (Japan); Yoshida, Mariko; Hori, Masaaki; Kamagata, Koji; Suzuki, Michimasa; Fukunaga, Issei; Kamiya, Kouhei; Aoki, Shigeki [Juntendo University School of Medicine, Department of Radiology, Tokyo (Japan); Yokoyama, Kazumasa; Hattori, Nobutaka [Juntendo University School of Medicine, Department of Neurology, Tokyo (Japan); Inoue, Tomio [Yokohama City University Graduate School of Medicine, Department of Radiology, Yokohama (Japan)

    2015-06-01

    To compare the significance of the two-compartment model, considering diffusional anisotropy with conventional diffusion analyzing methods regarding the detection of occult changes in normal-appearing white matter (NAWM) of multiple sclerosis (MS). Diffusion-weighted images (nine b-values with six directions) were acquired from 12 healthy female volunteers (22-52 years old, median 33 years) and 13 female MS patients (24-48 years old, median 37 years). Diffusion parameters based on the two-compartment model of water diffusion considering diffusional anisotropy was calculated by a proposed method. Other parameters including diffusion tensor imaging and conventional apparent diffusion coefficient (ADC) were also obtained. They were compared statistically between the control and MS groups. Diffusion of the slow diffusion compartment in the radial direction of neuron fibers was elevated in MS patients (0.121 x 10{sup -3} mm{sup 2}/s) in comparison to control (0.100 x 10{sup -3} mm{sup 2}/s), the difference being significant (P = 0.001). The difference between the groups was not significant in other comparisons, including conventional ADC and fractional anisotropy (FA) of diffusion tensor imaging. The proposed method was applicable to clinically acceptable small data. The parameters obtained by this method improved the detectability of occult changes in NAWM compared to the conventional methods. (orig.)

  8. Diffusion tensor tractography of normal and compressed spinal cord: a preliminary study at 3.0 T MR

    International Nuclear Information System (INIS)

    Wang Wei; Chang Shixin; Hao Nanxin; Du Yushan; Wang Yibin; Zong Genlin; Cao Kaiming; Lu Jianping; Zhao Cheng; Qin Wen

    2007-01-01

    Objective: To study the feasibility and clinical values of diffusion tensor tractography (DTT) in the spinal cord at 3.0 T MR. Methods: Forty patients with spinal cord compression including cervical cord herniation and cervical spondylosis (30 cases), tumors in spinal canal (9 cases) and old injury in cervical vertebrae (1 cases) and 20 healthy volunteers participated in this study. Single-shot spin- echo echo-planar diffusion tensor sequence for tractography of the spinal cord was performed. The fibers of spinal cord were visualized by using fiber tracking software. Results: On the DTT maps, the normal spinal cord was depicted as a fiber tract showing color-encoded cephalocaudally, which indicated anisotropy in the cephalocaudal direction. By setting two ROI, the main spinal cord fiber tracts, such as corticospinal or spinothalamic tract, were visualized. The tracts from two sides of the brain did not completely cross. It was asymmetric in the number of tracts on the two sides in most normal subjects (8/10). The tracts of all patients with cord compression were seen oppressed or damaged in different degrees. The DTT in patients with cervical spondylosis and extramedullary-intradural neurolemmoma demonstrated that tracts were oppressed but not damaged. The DTT in one ependymoma showed that tract was markedly compressed and slightly damaged. Conclusion: DTT is a promising tool for demonstrating the spinal cord tracts and abnormalities, can provide useful information for the localization of compression and evaluation of the impairment extent on the white matter tracts of the spinal cord. (authors)

  9. Diffusion tensor imaging and tractography in clinical neuro sciences

    International Nuclear Information System (INIS)

    Zarei, M.; Johansen-Berg, H.; Matthews, P.M.

    2003-01-01

    Rapidly evolving MR technology has allowed better understanding of structure and function of the human brain. Diffusion weighted MRI was developed two decades ago and it is now well established in diagnosis of acute ischaemia in patients with stroke. Diffusion tensor MRI uses the same principles but takes a step further allowing US to measure magnitude of the diffusion along different directions. This lead to the development of diffusion tensor tractography, a technique by which major neural pathways in the living brain can be visualized. There is a growing interest in exploring possible use of these techniques in clinical neurology and psychiatry. This article aims to review the principles of this technique and recent discoveries which may help US to better understand neurological and psychiatric disorders

  10. Real-time MR diffusion tensor and Q-ball imaging using Kalman filtering

    International Nuclear Information System (INIS)

    Poupon, C.; Roche, A.; Dubois, J.; Mangin, J.F.; Poupon, F.

    2008-01-01

    Diffusion magnetic resonance imaging (dMRI) has become an established research tool for the investigation of tissue structure and orientation. In this paper, we present a method for real-time processing of diffusion tensor and Q-ball imaging. The basic idea is to use Kalman filtering framework to fit either the linear tensor or Q-ball model. Because the Kalman filter is designed to be an incremental algorithm, it naturally enables updating the model estimate after the acquisition of any new diffusion-weighted volume. Processing diffusion models and maps during ongoing scans provides a new useful tool for clinicians, especially when it is not possible to predict how long a subject may remain still in the magnet. First, we introduce the general linear models corresponding to the two diffusion tensor and analytical Q-ball models of interest. Then, we present the Kalman filtering framework and we focus on the optimization of the diffusion orientation sets in order to speed up the convergence of the online processing. Last, we give some results on a healthy volunteer for the online tensor and the Q-ball model, and we make some comparisons with the conventional offline techniques used in the literature. We could achieve full real-time for diffusion tensor imaging and deferred time for Q-ball imaging, using a single workstation. (authors)

  11. The arbitrary order mimetic finite difference method for a diffusion equation with a non-symmetric diffusion tensor

    Science.gov (United States)

    Gyrya, V.; Lipnikov, K.

    2017-11-01

    We present the arbitrary order mimetic finite difference (MFD) discretization for the diffusion equation with non-symmetric tensorial diffusion coefficient in a mixed formulation on general polygonal meshes. The diffusion tensor is assumed to be positive definite. The asymmetry of the diffusion tensor requires changes to the standard MFD construction. We present new approach for the construction that guarantees positive definiteness of the non-symmetric mass matrix in the space of discrete velocities. The numerically observed convergence rate for the scalar quantity matches the predicted one in the case of the lowest order mimetic scheme. For higher orders schemes, we observed super-convergence by one order for the scalar variable which is consistent with the previously published result for a symmetric diffusion tensor. The new scheme was also tested on a time-dependent problem modeling the Hall effect in the resistive magnetohydrodynamics.

  12. Automatic extraction of the cingulum bundle in diffusion tensor tract-specific analysis. Feasibility study in Parkinson's disease with and without dementia

    International Nuclear Information System (INIS)

    Ito, Kenji; Masutani, Yoshitaka; Suzuki, Yuichi; Ino, Kenji; Kunimatsu, Akira; Ohtomo, Kuni; Kamagata, Koji; Yasmin, Hasina; Aoki, Shigeki

    2013-01-01

    Tract-specific analysis (TSA) measures diffusion parameters along a specific fiber that has been extracted by fiber tracking using manual regions of interest (ROIs), but TSA is limited by its requirement for manual operation, poor reproducibility, and high time consumption. We aimed to develop a fully automated extraction method for the cingulum bundle (CB) and to apply the method to TSA in neurobehavioral disorders such as Parkinson's disease (PD). We introduce the voxel classification (VC) and auto diffusion tensor fiber-tracking (AFT) methods of extraction. The VC method directly extracts the CB, skipping the fiber-tracking step, whereas the AFT method uses fiber tracking from automatically selected ROIs. We compared the results of VC and AFT to those obtained by manual diffusion tensor fiber tracking (MFT) performed by 3 operators. We quantified the Jaccard similarity index among the 3 methods in data from 20 subjects (10 normal controls [NC] and 10 patients with Parkinson's disease dementia [PDD]). We used all 3 extraction methods (VC, AFT, and MFT) to calculate the fractional anisotropy (FA) values of the anterior and posterior CB for 15 NC subjects, 15 with PD, and 15 with PDD. The Jaccard index between results of AFT and MFT, 0.72, was similar to the inter-operator Jaccard index of MFT. However, the Jaccard indices between VC and MFT and between VC and AFT were lower. Consequently, the VC method classified among 3 different groups (NC, PD, and PDD), whereas the others classified only 2 different groups (NC, PD or PDD). For TSA in Parkinson's disease, the VC method can be more useful than the AFT and MFT methods for extracting the CB. In addition, the results of patient data analysis suggest that a reduction of FA in the posterior CB may represent a useful biological index for monitoring PD and PDD. (author)

  13. Data quality in diffusion tensor imaging studies of the preterm brain: a systematic review.

    Science.gov (United States)

    Pieterman, Kay; Plaisier, Annemarie; Govaert, Paul; Leemans, Alexander; Lequin, Maarten H; Dudink, Jeroen

    2015-08-01

    To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount. To review the literature to evaluate acquisition and processing methodology in diffusion tensor imaging studies of preterm infants. We searched the Embase, Medline, Web of Science and Cochrane databases for relevant papers published between 2003 and 2013. The following keywords were included in our search: prematurity, neuroimaging, brain, and diffusion tensor imaging. We found 74 diffusion tensor imaging studies in preterm infants meeting our inclusion criteria. There was wide variation in acquisition and processing methodology, and we found incomplete reporting of these settings. Nineteen studies (26%) reported the use of neonatal hardware. Data quality assessment was not reported in 13 (18%) studies. Artefacts-correction and data-exclusion was not reported in 33 (45%) and 18 (24%) studies, respectively. Tensor estimation algorithms were reported in 56 (76%) studies but were often suboptimal. Diffusion tensor imaging acquisition and processing settings are incompletely described in current literature, vary considerably, and frequently do not meet the highest standards.

  14. Predicting patterns of glioma recurrence using diffusion tensor imaging

    International Nuclear Information System (INIS)

    Price, Stephen J.; Pickard, John D.; Jena, Rajesh; Burnet, Neil G.; Carpenter, T.A.; Gillard, Jonathan H.

    2007-01-01

    Although multimodality therapy for high-grade gliomas is making some improvement in outcome, most patients will still die from their disease within a short time. We need tools that allow treatments to be tailored to an individual. In this study we used diffusion tensor imaging (DTI), a technique sensitive to subtle disruption of white-matter tracts due to tumour infiltration, to see if it can be used to predict patterns of glioma recurrence. In this study we imaged 26 patients with gliomas using DTI. Patients were imaged after 2 years or on symptomatic tumour recurrence. The diffusion tensor was split into its isotropic (p) and anisotropic (q) components, and these were plotted on T 2 -weighted images to show the pattern of DTI abnormality. This was compared to the pattern of recurrence. Three DTI patterns could be identified: (a) a diffuse pattern of abnormality where p exceeded q in all directions and was associated with diffuse increase in tumour size; (b) a localised pattern of abnormality where the tumour recurred in one particular direction; and (c) a pattern of minimal abnormality seen in some patients with or without evidence of recurrence. Diffusion tensor imaging is able to predict patterns of tumour recurrence and may allow better individualisation of tumour management and stratification for randomised controlled trials. (orig.)

  15. Predicting patterns of glioma recurrence using diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Price, Stephen J.; Pickard, John D. [University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, Addenbrooke' s Hospital, Academic Neurosurgery Unit (United Kingdom); University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, Addenbrooke' s Hospital, Wolfson Brain Imaging Centre, Department of Clinical Neurosciences (United Kingdom); Jena, Rajesh; Burnet, Neil G. [University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, Addenbrooke' s Hospital, University Department of Oncology (United Kingdom); Carpenter, T.A. [University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, Addenbrooke' s Hospital, Wolfson Brain Imaging Centre, Department of Clinical Neurosciences (United Kingdom); Gillard, Jonathan H. [University of Cambridge and Cambridge University Hospitals NHS Foundation Trust, Addenbrooke' s Hospital, University Department of Radiology (United Kingdom)

    2007-07-15

    Although multimodality therapy for high-grade gliomas is making some improvement in outcome, most patients will still die from their disease within a short time. We need tools that allow treatments to be tailored to an individual. In this study we used diffusion tensor imaging (DTI), a technique sensitive to subtle disruption of white-matter tracts due to tumour infiltration, to see if it can be used to predict patterns of glioma recurrence. In this study we imaged 26 patients with gliomas using DTI. Patients were imaged after 2 years or on symptomatic tumour recurrence. The diffusion tensor was split into its isotropic (p) and anisotropic (q) components, and these were plotted on T{sub 2}-weighted images to show the pattern of DTI abnormality. This was compared to the pattern of recurrence. Three DTI patterns could be identified: (a) a diffuse pattern of abnormality where p exceeded q in all directions and was associated with diffuse increase in tumour size; (b) a localised pattern of abnormality where the tumour recurred in one particular direction; and (c) a pattern of minimal abnormality seen in some patients with or without evidence of recurrence. Diffusion tensor imaging is able to predict patterns of tumour recurrence and may allow better individualisation of tumour management and stratification for randomised controlled trials. (orig.)

  16. White matter correlates of cognitive domains in normal aging with diffusion tensor imaging

    Directory of Open Access Journals (Sweden)

    Efrat eSasson

    2013-03-01

    Full Text Available The ability to perform complex as well as simple cognitive tasks engages a network of brain regions that is mediated by the white matter fiber bundles connecting them. Different cognitive tasks employ distinctive white matter fiber bundles. The temporal lobe and its projections subserve a variety of key functions known to deteriorate during aging. In a cohort of 52 healthy subjects (ages 25-82 years, we performed voxel-wise regression analysis correlating performance in higher-order cognitive domains (executive function, information processing speed, and memory with white matter integrity, as measured by diffusion tensor imaging (DTI fiber tracking in the temporal lobe projections (uncinate fasciculus (UF, fornix, cingulum, inferior longitudinal fasciculus (ILF, and superior longitudinal fasciculus (SLF. The fiber tracts were spatially registered and statistical parametric maps were produced to spatially localize the significant correlations. Results showed that performance in the executive function domain is correlated with DTI parameters in the left SLF and right UF; performance in the information processing speed domain is correlated with fractional anisotropy (FA in the left cingulum, left fornix, right and left ILF and SLF; and the memory domain shows significant correlations with DTI parameters in the right fornix, right cingulum, left ILF, left SLF and right UF. These findings suggest that DTI tractography enables anatomical definition of region of interest for correlation of behavioral parameters with diffusion indices, and functionality can be correlated with white matter integrity.

  17. Diffusion-Weighted Imaging and Diffusion Tensor Imaging of Asymptomatic Lumbar Disc Herniation

    OpenAIRE

    Sakai, Toshinori; Miyagi, Ryo; Yamabe, Eiko; Fujinaga, Yasunari; Bhatia, Nitin N.; Yoshioka, Hiroshi

    2014-01-01

    Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) were performedon a healthy 31-year-old man with asymptomatic lumbar disc herniation. Althoughthe left S1 nerve root was obviously entrapped by a herniated mass, neither DWI nor DTI showed any significant findings for the nerve root. Decreased apparent diffusion coefficient (ADC) values and increased fractional anisotropy (FA) values were found. These results are contrary to those in previously published studies of symptomatic...

  18. Data quality in diffusion tensor imaging studies of the preterm brain: a systematic review

    Energy Technology Data Exchange (ETDEWEB)

    Pieterman, Kay; Plaisier, Annemarie; Dudink, Jeroen [Erasmus Medical Center - Sophia, Division of Neonatology, Department of Pediatrics, dr. Molewaterplein 60, GJ, Rotterdam (Netherlands); Department of Radiology, Erasmus Medical Center, Rotterdam (Netherlands); Govaert, Paul [Erasmus Medical Center - Sophia, Division of Neonatology, Department of Pediatrics, dr. Molewaterplein 60, GJ, Rotterdam (Netherlands); Department of Pediatrics, Koningin Paola Children' s Hospital, Antwerp (Belgium); Leemans, Alexander [University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands); Lequin, Maarten H. [Department of Radiology, Erasmus Medical Center, Rotterdam (Netherlands)

    2015-08-15

    To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount. To review the literature to evaluate acquisition and processing methodology in diffusion tensor imaging studies of preterm infants. We searched the Embase, Medline, Web of Science and Cochrane databases for relevant papers published between 2003 and 2013. The following keywords were included in our search: prematurity, neuroimaging, brain, and diffusion tensor imaging. We found 74 diffusion tensor imaging studies in preterm infants meeting our inclusion criteria. There was wide variation in acquisition and processing methodology, and we found incomplete reporting of these settings. Nineteen studies (26%) reported the use of neonatal hardware. Data quality assessment was not reported in 13 (18%) studies. Artefacts-correction and data-exclusion was not reported in 33 (45%) and 18 (24%) studies, respectively. Tensor estimation algorithms were reported in 56 (76%) studies but were often suboptimal. Diffusion tensor imaging acquisition and processing settings are incompletely described in current literature, vary considerably, and frequently do not meet the highest standards. (orig.)

  19. Data quality in diffusion tensor imaging studies of the preterm brain: a systematic review

    International Nuclear Information System (INIS)

    Pieterman, Kay; Plaisier, Annemarie; Dudink, Jeroen; Govaert, Paul; Leemans, Alexander; Lequin, Maarten H.

    2015-01-01

    To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount. To review the literature to evaluate acquisition and processing methodology in diffusion tensor imaging studies of preterm infants. We searched the Embase, Medline, Web of Science and Cochrane databases for relevant papers published between 2003 and 2013. The following keywords were included in our search: prematurity, neuroimaging, brain, and diffusion tensor imaging. We found 74 diffusion tensor imaging studies in preterm infants meeting our inclusion criteria. There was wide variation in acquisition and processing methodology, and we found incomplete reporting of these settings. Nineteen studies (26%) reported the use of neonatal hardware. Data quality assessment was not reported in 13 (18%) studies. Artefacts-correction and data-exclusion was not reported in 33 (45%) and 18 (24%) studies, respectively. Tensor estimation algorithms were reported in 56 (76%) studies but were often suboptimal. Diffusion tensor imaging acquisition and processing settings are incompletely described in current literature, vary considerably, and frequently do not meet the highest standards. (orig.)

  20. Resolving crossings in the corticospinal tract by two-tensor streamline tractography

    DEFF Research Database (Denmark)

    Qazi, Arish Asif; Radmanesh, Alireza; O'Donnell, Lauren

    2009-01-01

    An inherent drawback of the traditional diffusion tensor model is its limited ability to provide detailed information about multidirectional fiber architecture within a voxel. This leads to erroneous fiber tractography results in locations where fiber bundles cross each other. This may lead to th...

  1. Homogeneity based segmentation and enhancement of Diffusion Tensor Images : a white matter processing framework

    NARCIS (Netherlands)

    Rodrigues, P.R.

    2011-01-01

    In diffusion magnetic resonance imaging (DMRI) the Brownian motion of the water molecules, within biological tissue, is measured through a series of images. In diffusion tensor imaging (DTI) this diffusion is represented using tensors. DTI describes, in a non-invasive way, the local anisotropy

  2. Brain diffusion tensor MRI in systematic lupus erythematosus: A systematic review.

    Science.gov (United States)

    Costallat, Beatriz Lavras; Ferreira, Daniel Miranda; Lapa, Aline Tamires; Rittner, Letícia; Costallat, Lilian Tereza Lavras; Appenzeller, Simone

    2018-01-01

    Diffusion tensor imaging (DTI) maps the brain's microstructure by measuring fractional anisotropy (FA) and mean diffusivity (MD). This systematic review describes brain diffusion tensor Magnetic resonance imaging (MRI) studies in systemic lupus erythematosus (SLE).The literature was reviewed following the PRISMA guidelines and using the terms "lupus", "systemic lupus erythematosus", "SLE", "diffusion tensor imaging", "DTI", "white matter" (WM), "microstructural damage", "tractography", and "fractional anisotropy"; the search included articles published in English from January 2007 to April 2017. The subjects included in the study were selected according to the ACR criteria and included 195 SLE patients with neuropsychiatric manifestation (NPSLE), 299 without neuropsychiatric manifestation (non-NPSLE), and 423 healthy controls (HC). Most studies identified significantly reduced FA and increased MD values in several WM regions of both NPSLE and non-NPSLE patients compared to HC. Subclinical microstructural changes were observed in either regional areas or the entire brain in both the non-NPSLE and NPSLE groups. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Diffusion tensor magnetic resonance imaging driven growth modeling for radiotherapy target definition in glioblastoma

    DEFF Research Database (Denmark)

    Jensen, Morten B; Guldberg, Trine L; Harbøll, Anja

    2017-01-01

    the microscopic tumor cell spread. Gliomas favor spread along the white matter fiber tracts. Tumor growth models incorporating the MRI diffusion tensors (DTI) allow to account more consistently for the glioma growth. The aim of the study was to investigate the potential of a DTI driven growth model to improve...... target definition in glioblastoma (GBM). MATERIAL AND METHODS: Eleven GBM patients were scanned using T1w, T2w FLAIR, T1w + Gd and DTI. The brain was segmented into white matter, gray matter and cerebrospinal fluid. The Fisher-Kolmogorov growth model was used assuming uniform proliferation...

  4. Performance of unscented Kalman filter tractography in edema: Analysis of the two-tensor model.

    Science.gov (United States)

    Liao, Ruizhi; Ning, Lipeng; Chen, Zhenrui; Rigolo, Laura; Gong, Shun; Pasternak, Ofer; Golby, Alexandra J; Rathi, Yogesh; O'Donnell, Lauren J

    2017-01-01

    Diffusion MRI tractography is increasingly used in pre-operative neurosurgical planning to visualize critical fiber tracts. However, a major challenge for conventional tractography, especially in patients with brain tumors, is tracing fiber tracts that are affected by vasogenic edema, which increases water content in the tissue and lowers diffusion anisotropy. One strategy for improving fiber tracking is to use a tractography method that is more sensitive than the traditional single-tensor streamline tractography. We performed experiments to assess the performance of two-tensor unscented Kalman filter (UKF) tractography in edema. UKF tractography fits a diffusion model to the data during fiber tracking, taking advantage of prior information from the previous step along the fiber. We studied UKF performance in a synthetic diffusion MRI digital phantom with simulated edema and in retrospective data from two neurosurgical patients with edema affecting the arcuate fasciculus and corticospinal tracts. We compared the performance of several tractography methods including traditional streamline, UKF single-tensor, and UKF two-tensor. To provide practical guidance on how the UKF method could be employed, we evaluated the impact of using various seed regions both inside and outside the edematous regions, as well as the impact of parameter settings on the tractography sensitivity. We quantified the sensitivity of different methods by measuring the percentage of the patient-specific fMRI activation that was reached by the tractography. We expected that diffusion anisotropy threshold parameters, as well as the inclusion of a free water model, would significantly influence the reconstruction of edematous WM fiber tracts, because edema increases water content in the tissue and lowers anisotropy. Contrary to our initial expectations, varying the fractional anisotropy threshold and including a free water model did not affect the UKF two-tensor tractography output appreciably in

  5. Usefulness of Diffusion Tensor Imaging of White Matter in Alzheimer Disease and Vascular Dementia

    International Nuclear Information System (INIS)

    Sugihara, S.; Kinoshita, T.; Matsusue, E.; Fujii, S.; Ogawa, T.

    2004-01-01

    Purpose: To evaluate the usefulness of diffusion tensor imaging in detecting the water diffusivity caused by neuro pathological change in Alzheimer disease and vascular dementia. Material and Methods: Twenty patients with Alzheimer disease, 20 with vascular dementia, and 10 control subjects were examined. Diffusion tensor imaging applied diffusion gradient encoding in six non-collinear directions. Fractional anisotropy values were compared in the genu and splenium of the corpus callosum, and anterior and posterior white matter among the three groups. Results: In the patients with Alzheimer disease, fractional anisotropy values of the posterior white matter were significantly lower than those of controls. In patients with vascular dementia, fractional anisotropy values of the anterior white matter tended to be lower than those of the posterior white matter (P=0.07). Conclusion: Diffusion tensor imaging reflects the neuro pathological changes in the white matter, and may be useful in the diagnosis of Alzheimer disease and vascular dementia. Keywords: Alzheimer disease, .; diffusion tensor imaging, .; vascular dementia

  6. Diffusion tensor metrics as biomarkers in Alzheimer's disease.

    Directory of Open Access Journals (Sweden)

    Julio Acosta-Cabronero

    Full Text Available Although diffusion tensor imaging has been a major research focus for Alzheimer's disease in recent years, it remains unclear whether it has sufficient stability to have biomarker potential. To date, frequently inconsistent results have been reported, though lack of standardisation in acquisition and analysis make such discrepancies difficult to interpret. There is also, at present, little knowledge of how the biometric properties of diffusion tensor imaging might evolve in the course of Alzheimer's disease.The biomarker question was addressed in this study by adopting a standardised protocol both for the whole brain (tract-based spatial statistics, and for a region of interest: the midline corpus callosum. In order to study the evolution of tensor changes, cross-sectional data from very mild (N = 21 and mild (N = 22 Alzheimer's disease patients were examined as well as a longitudinal cohort (N = 16 that had been rescanned at 12 months.The results revealed that increased axial and mean diffusivity are the first abnormalities to occur and that the first region to develop such significant differences was mesial parietal/splenial white matter; these metrics, however, remained relatively static with advancing disease indicating they are suitable as 'state-specific' markers. In contrast, increased radial diffusivity, and therefore decreased fractional anisotropy-though less detectable early-became increasingly abnormal with disease progression, and, in the splenium of the corpus callosum, correlated significantly with dementia severity; these metrics therefore appear 'stage-specific' and would be ideal for monitoring disease progression. In addition, the cross-sectional and longitudinal analyses showed that the progressive abnormalities in radial diffusivity and fractional anisotropy always occurred in areas that had first shown an increase in axial and mean diffusivity. Given that the former two metrics correlate with dementia severity

  7. Application of diffusion tensor imaging in neurosurgery; Anwendung der Diffusions-Tensor-Bildgebung in der Neurochirurgie

    Energy Technology Data Exchange (ETDEWEB)

    Saur, R. [Sektion fuer Experimentelle Kernspinresonanz des ZNS, Abt. Neuroradiologie, Universitaetsklinikum Tuebingen (Germany); Augenklinik des Universitaetsklinikums Tuebingen (Germany); Klinik fuer Psychiatrie und Psychotherapie des Universitaetsklinikums Tuebingen (Germany); Gharabaghi, A. [Klinik fuer Neurochirurgie des Universitaetsklinikums Tuebingen (Germany); Erb, M. [Sektion fuer Experimentelle Kernspinresonanz des ZNS, Abt. Neuroradiologie, Universitaetsklinikum Tuebingen (Germany)

    2007-07-01

    Knowledge about integrity and location of fibre tracts arising from eloquent cortical areas is important to plan neurosurgical interventions and to allow maximization of resection of pathological tissue while preserving vital white matter tracts. Diffusion Tensor Imaging (DTI) is so far the only method to get preoperatively an impression of the individual complexity of nerve bundles. Thereby nerve fibres are not mapped directly. They are derived indirectly by analysis of the directional distribution of diffusion of water molecules which is influenced mainly by large fibre tracts. From acquisition to reconstruction and visualisation of the fibre tracts many representational stages and working steps have to be passed. Exact knowledge about problems of Diffusion Imaging is important for interpretation of the results. Particularly, brain tumor edema, intraoperative brain shift, MR-artefacts and limitations of the mathematical models and algorithms challenge DTI-developers and applicants. (orig.)

  8. Analysis of the diffusion tensor imaging parameters of a normal cervical spinal cord in a healthy population.

    Science.gov (United States)

    Wei, Liang-Feng; Wang, Shou-Sen; Zheng, Zhao-Cong; Tian, Jun; Xue, Liang

    2017-05-01

    Diffusion tensor imaging (DTI) shows great advantage in the diagnosis of brain diseases, including cervical spinal cord (CSC) disease. This study aims to obtain the normal values of the DTI parameters for a healthy population and to establish a baseline for CSC disease diagnosis using DTI. A total of 36 healthy adults were subjected to magnetic resonance imaging (MRI) for the entire CSC using the Siemens 3.0 T MR System. Sagittal DTI acquisition was carried out with a single-shot spin-echo echo-planar imaging (EPI) sequence along 12 non-collinear directions. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values were determined at different cervical levels using a region of interest (ROI) method, following which they were correlated with parameters, like age and sex. Further, diffusion tensor tracking (DTT) was carried out to reconstruct the white matter fiber bundles of the CSC. The full and complete fiber bundle structure of a normal CSC was confirmed in both the T2-weighted and DTI images. The FA and ADC values were significantly negatively correlated with each other and showed strongly negative and positive correlations with age, respectively, but not with sex. Additionally, there was no significant difference between the FA and the ADC values at different cervical levels. The DTI technique can act as an important supplement to the conventional MRI technique for CSC observation. Moreover, the FA and ADC values can be used as sensitive parameters in the DTI study on the CSC by taking the effects of age into consideration.

  9. An introduction to visualization of diffusion tensor imaging and its applications

    NARCIS (Netherlands)

    Vilanova, A.; Zhang, S.; Kindlmann, G.; Laidlaw, D.H.; Weickert, J.; Hagen, H.

    2005-01-01

    Summary. Water diffusion is anisotropic in organized tissues such as white matter and muscle. Diffusion tensor imaging (DTI), a non-invasive MR technique, measures water self-diffusion rates and thus gives an indication of the underlying tissue microstructure. The diffusion rate is often expressed

  10. Diffusion Capillary Phantom vs. Human Data: Outcomes for Reconstruction Methods Depend on Evaluation Medium

    Directory of Open Access Journals (Sweden)

    Sarah D. Lichenstein

    2016-09-01

    Full Text Available Purpose: Diffusion MRI provides a non-invasive way of estimating structural connectivity in the brain. Many studies have used diffusion phantoms as benchmarks to assess the performance of different tractography reconstruction algorithms and assumed that the results can be applied to in vivo studies. Here we examined whether quality metrics derived from a common, publically available, diffusion phantom can reliably predict tractography performance in human white matter tissue. Material and Methods: We compared estimates of fiber length and fiber crossing among a simple tensor model (diffusion tensor imaging, a more complicated model (ball-and-sticks and model-free (diffusion spectrum imaging, generalized q-sampling imaging reconstruction methods using a capillary phantom and in vivo human data (N=14. Results: Our analysis showed that evaluation outcomes differ depending on whether they were obtained from phantom or human data. Specifically, the diffusion phantom favored a more complicated model over a simple tensor model or model-free methods for resolving crossing fibers. On the other hand, the human studies showed the opposite pattern of results, with the model-free methods being more advantageous than model-based methods or simple tensor models. This performance difference was consistent across several metrics, including estimating fiber length and resolving fiber crossings in established white matter pathways. Conclusions: These findings indicate that the construction of current capillary diffusion phantoms tends to favor complicated reconstruction models over a simple tensor model or model-free methods, whereas the in vivo data tends to produce opposite results. This brings into question the previous phantom-based evaluation approaches and suggests that a more realistic phantom or simulation is necessary to accurately predict the relative performance of different tractography reconstruction methods. Acronyms: BSM: ball-and-sticks model; d

  11. Intramyocellular lipid dependence on skeletal muscle fiber type and orientation characterized by diffusion tensor imaging and 1H-MRS

    Science.gov (United States)

    Valaparla, Sunil K.; Gao, Feng; Abdul-Ghani, Muhammad; Clarke, Geoffrey D.

    2014-03-01

    When muscle fibers are aligned with the B0 field, intramyocellular lipids (IMCL), important for providing energy during physical activity, can be resolved in proton magnetic resonance spectra (1H-MRS). Various muscles of the leg differ significantly in their proportion of fibers and angular distribution. This study determined the influence of muscle fiber type and orientation on IMCL using 1H-MRS and diffusion tensor imaging (DTI). Muscle fiber orientation relative to B0 was estimated by pennation angle (PA) measurements from DTI, providing orientation-specific extramyocellular lipid (EMCL) chemical shift data that were used for subject-specific IMCL quantification. Vastus lateralis (VL), tibialis anterior (TA) and soleus (SO) muscles of 6 healthy subjects (21-40 yrs) were studied on a Siemens 3T MRI system with a flex 4-channel coil. 1H-MRS were acquired using stimulated echo acquisition mode (STEAM, TR=3s, TE=270ms). DTI was performed using single shot EPI (b=600s/mm2, 30 directions, TR=4.5s, TE=82ms, and ten×5mm slices) with center slice indexed to the MRS voxel. The average PA's measured from ROI analysis of primary eigenvectors were PA=19.46+/-5.43 for unipennate VL, 15.65+/-3.73 for multipennate SO, and 7.04+/-3.34 for bipennate TA. Chemical shift (CS) was calculated using [3cos2θ-1] dependence: 0.17+/-0.02 for VL, 0.18+/-0.01 for SO and 0.19+/-0.004 ppm for TA. IMCL-CH2 concentrations from spectral analysis were 12.77+/-6.3 for VL, 3.07+/-1.63 for SO and 0.27+/-0.08 mmol/kg ww for TA. Small PA's were measured in TA and large CS with clear separation between EMCL and IMCL peaks were observed. Larger variations in PA were measured VL and SO resulting in an increased overlap of the EMCL on IMCL peaks.

  12. Diffusion tensor in electron swarm transport

    International Nuclear Information System (INIS)

    Makabe, T.; Mori, T.

    1983-01-01

    Expression for the diffusion tensor of the electron (or light ion) swarm is presented from the higher-order expansion of the velocity distribution in the Boltzmann equation in hydrodynamic stage. Derived diffusion coefficients for the transverse and longitudinal directions include the additional terms representative of the curvature effect under the action of an electric field with the usual-two-term expressions. Numerical analysis is given for the electron swarm in model gases having the momentum transfer cross section Qsub(m)(epsilon)=Q 0 epsilon sup(beta) (β=0, 1/2, 1) using the present theory. As the result, appreciable degree of discrepancy appears between the transverse diffusion coefficient defined here and the conventional expression with increasing of β in Qsub(m). (Author)

  13. Diffusion properties of NAA in human corpus callosum as studied with diffusion tensor spectroscopy.

    Science.gov (United States)

    Upadhyay, Jaymin; Hallock, Kevin; Erb, Kelley; Kim, Dae-Shik; Ronen, Itamar

    2007-11-01

    In diffusion tensor imaging (DTI) the anisotropic movement of water is exploited to characterize microstructure. One confounding issue of DTI is the presence of intra- and extracellular components contributing to the measured diffusivity. This causes an ambiguity in determining the underlying cause of diffusion properties, particularly the fractional anisotropy (FA). In this study an intracellular constituent, N-acetyl aspartate (NAA), was used to probe intracellular diffusion, while water molecules were used to probe the combined intra- and extracellular diffusion. NAA and water diffusion measurements were made in anterior and medial corpus callosum (CC) regions, which are referred to as R1 and R2, respectively. FA(NAA) was found to be greater than FA(Water) in both CC regions, thus indicating a higher degree of anisotropy within the intracellular space in comparison to the combined intra- and extracellular spaces. A decreasing trend in the FA of NAA and water was observed between R1 and R2, while the radial diffusivity (RD) for both molecules increased. The increase in RD(NAA) is particularly significant, thus explaining the more significant decrease in FA(NAA) between the two regions. It is suggested that diffusion tensor spectroscopy of NAA can potentially be used to further characterize microscopic anatomic organization in white matter. Copyright 2007 Wiley-Liss, Inc.

  14. Mid-callosal plane determination using preferred directions from diffusion tensor images

    Science.gov (United States)

    Costa, André L.; Rittner, Letícia; Lotufo, Roberto A.; Appenzeller, Simone

    2015-03-01

    The corpus callosum is the major brain structure responsible for inter{hemispheric communication between neurons. Many studies seek to relate corpus callosum attributes to patient characteristics, cerebral diseases and psychological disorders. Most of those studies rely on 2D analysis of the corpus callosum in the mid-sagittal plane. However, it is common to find conflicting results among studies, once many ignore methodological issues and define the mid-sagittal plane based on precary or invalid criteria with respect to the corpus callosum. In this work we propose a novel method to determine the mid-callosal plane using the corpus callosum internal preferred diffusion directions obtained from diffusion tensor images. This plane is analogous to the mid-sagittal plane, but intended to serve exclusively as the corpus callosum reference. Our method elucidates the great potential the directional information of the corpus callosum fibers have to indicate its own referential. Results from experiments with five image pairs from distinct subjects, obtained under the same conditions, demonstrate the method effectiveness to find the corpus callosum symmetric axis relative to the axial plane.

  15. CUDA-accelerated geodesic ray-tracing for fiber-tracking

    NARCIS (Netherlands)

    van Aart, Evert; Sepasian, N.; Jalba, A.C.; Vilanova, A.

    2011-01-01

    Diffusion Tensor Imaging (DTI) allows to noninvasively measure the diffusion of water in fibrous tissue. By reconstructing the fibers from DTI data using a fiber-tracking algorithm, we can deduce the structure of the tissue. In this paper, we outline an approach to accelerating such a fiber-tracking

  16. Love songs, bird brains and diffusion tensor imaging.

    Science.gov (United States)

    De Groof, Geert; Van der Linden, Annemie

    2010-08-01

    The song control system of songbirds displays a remarkable seasonal neuroplasticity in species in which song output also changes seasonally. Thus far, this song control system has been extensively analyzed by histological and electrophysiological methods. However, these approaches do not provide a global view of the brain and/or do not allow repeated measurements, which are necessary to establish causal correlations between alterations in neural substrate and behavior. Research has primarily been focused on the song nuclei themselves, largely neglecting their interconnections and other brain regions involved in seasonally changing behavior. In this review, we introduce and explore the song control system of songbirds as a natural model for brain plasticity. At the same time, we point out the added value of the songbird brain model for in vivo diffusion tensor techniques and its derivatives. A compilation of the diffusion tensor imaging (DTI) data obtained thus far in this system demonstrates the usefulness of this in vivo method for studying brain plasticity. In particular, it is shown to be a perfect tool for long-term studies of morphological and cellular changes of specific brain circuits in different endocrine/photoperiod conditions. The method has been successfully applied to obtain quantitative measurements of seasonal changes of fiber tracts and nuclei from the song control system. In addition, outside the song control system, changes have been discerned in the optic chiasm and in an interhemispheric connection. DTI allows the detection of seasonal changes in a region analogous to the mammalian secondary auditory cortex and in regions of the 'social behavior network', an interconnected group of structures that controls multiple social behaviors, including aggression and courtship. DTI allows the demonstration, for the first time, that the songbird brain in its entirety exhibits an extreme seasonal plasticity which is not merely limited to the song control

  17. Impact of time-of-day on diffusivity measures of brain tissue derived from diffusion tensor imaging.

    Science.gov (United States)

    Thomas, Cibu; Sadeghi, Neda; Nayak, Amrita; Trefler, Aaron; Sarlls, Joelle; Baker, Chris I; Pierpaoli, Carlo

    2018-06-01

    Diurnal fluctuations in MRI measures of structural and functional properties of the brain have been reported recently. These fluctuations may have a physiological origin, since they have been detected using different MRI modalities, and cannot be explained by factors that are typically known to confound MRI measures. While preliminary evidence suggests that measures of structural properties of the brain based on diffusion tensor imaging (DTI) fluctuate as a function of time-of-day (TOD), the underlying mechanism has not been investigated. Here, we used a longitudinal within-subjects design to investigate the impact of time-of-day on DTI measures. In addition to using the conventional monoexponential tensor model to assess TOD-related fluctuations, we used a dual compartment tensor model that allowed us to directly assess if any change in DTI measures is due to an increase in CSF/free-water volume fraction or due to an increase in water diffusivity within the parenchyma. Our results show that Trace or mean diffusivity, as measured using the conventional monoexponential tensor model tends to increase systematically from morning to afternoon scans at the interface of grey matter/CSF, most prominently in the major fissures and the sulci of the brain. Interestingly, in a recent study of the glymphatic system, these same regions were found to show late enhancement after intrathecal injection of a CSF contrast agent. The increase in Trace also impacts DTI measures of diffusivity such as radial and axial diffusivity, but does not affect fractional anisotropy. The dual compartment analysis revealed that the increase in diffusivity measures from PM to AM was driven by an increase in the volume fraction of CSF-like free-water. Taken together, our findings provide important insight into the likely physiological origins of diurnal fluctuations in MRI measurements of structural properties of the brain. Published by Elsevier Inc.

  18. Diffusion tensor mode in imaging of intracranial epidermoid cysts: one step ahead of fractional anisotropy

    International Nuclear Information System (INIS)

    Jolapara, Milan; Kesavadas, Chandrasekharan; Saini, Jitender; Patro, Satya Narayan; Gupta, Arun Kumar; Kapilamoorthy, Tirur Raman; Bodhey, Narendra; Radhakrishnan, V.V.

    2009-01-01

    The signal characteristics of an epidermoid on T2-weighted imaging have been attributed to the presence of increased water content within the tumor. In this study, we explore the utility of diffusion tensor imaging (DTI) and diffusion tensor metrics (DTM) in knowing the microstructural anatomy of epidermoid cysts. DTI was performed in ten patients with epidermoid cysts. Directionally averaged mean diffusivity (D av ), exponential diffusion, and DTM-like fractional anisotropy (FA), diffusion tensor mode (mode), linear (CL), planar (CP), and spherical (CS) anisotropy were measured from the tumor as well as from the normal-looking white matter. Epidermoid cysts showed high FA. However, D av and exponential diffusion values did not show any restriction of diffusion. Diffusion tensor mode values were near -1, and CP values were high within the tumor. This suggested preferential diffusion of water molecules along a two-dimensional geometry (plane) in epidermoid cysts, which could be attributed to the parallel-layered arrangement of keratin filaments and flakes within these tumors. Thus, advanced imaging modalities like DTI with DTM can provide information regarding the microstructural anatomy of the epidermoid cysts. (orig.)

  19. Direct diffusion tensor estimation using a model-based method with spatial and parametric constraints.

    Science.gov (United States)

    Zhu, Yanjie; Peng, Xi; Wu, Yin; Wu, Ed X; Ying, Leslie; Liu, Xin; Zheng, Hairong; Liang, Dong

    2017-02-01

    To develop a new model-based method with spatial and parametric constraints (MB-SPC) aimed at accelerating diffusion tensor imaging (DTI) by directly estimating the diffusion tensor from highly undersampled k-space data. The MB-SPC method effectively incorporates the prior information on the joint sparsity of different diffusion-weighted images using an L1-L2 norm and the smoothness of the diffusion tensor using a total variation seminorm. The undersampled k-space datasets were obtained from fully sampled DTI datasets of a simulated phantom and an ex-vivo experimental rat heart with acceleration factors ranging from 2 to 4. The diffusion tensor was directly reconstructed by solving a minimization problem with a nonlinear conjugate gradient descent algorithm. The reconstruction performance was quantitatively assessed using the normalized root mean square error (nRMSE) of the DTI indices. The MB-SPC method achieves acceptable DTI measures at an acceleration factor up to 4. Experimental results demonstrate that the proposed method can estimate the diffusion tensor more accurately than most existing methods operating at higher net acceleration factors. The proposed method can significantly reduce artifact, particularly at higher acceleration factors or lower SNRs. This method can easily be adapted to MR relaxometry parameter mapping and is thus useful in the characterization of biological tissue such as nerves, muscle, and heart tissue. © 2016 American Association of Physicists in Medicine.

  20. An exploration into diffusion tensor imaging in the bovine ocular lens

    Directory of Open Access Journals (Sweden)

    Ehsan eVaghefi

    2013-03-01

    Full Text Available We describe our development of the diffusion tensor imaging modality for the bovine ocular lens. Diffusion gradients were added to a spin-echo pulse sequence and the relevant parameters of the sequence were refined to achieve good diffusion weighting in the lens tissue, which demonstrated heterogeneous regions of diffusive signal attenuation. Decay curves for b-value (loosely summarizes the strength of diffusion weighting and TE (determines the amount of MRI-obtained signal were used to estimate apparent diffusion coefficients (ADC and T2 in different lens regions. The ADCs varied by over an order of magnitude and revealed diffusive anisotropy in the lens. Up to 30 diffusion gradient directions, and 8 signal acquisition averages, were applied to lenses in culture in order to improve maps of diffusion tensor eigenvalues, equivalent to ADC, across the lens. From these maps, fractional anisotropy maps were calculated and compared to known spatial distributions of anisotropic molecular fluxes in the lens. This comparison suggested new hypotheses and experiments to quantitatively assess models of circulation in the avascular lens.

  1. Anisotropic diffusion tensor applied to temporal mammograms

    DEFF Research Database (Denmark)

    Karemore, Gopal; Brandt, Sami; Sporring, Jon

    2010-01-01

    changes related to  specific  effects  like  Hormonal  Replacement  Therapy  (HRT) and aging. Given effect-grouped patient data, we demonstrated how  anisotropic  diffusion  tensor  and  its  coherence  features computed in an anatomically oriented breast coordinate system followed by statistical learning...

  2. Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children.

    Science.gov (United States)

    Sreedharan, Ruma Madhu; Menon, Amitha C; James, Jija S; Kesavadas, Chandrasekharan; Thomas, Sanjeev V

    2015-03-01

    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms--visual verb generation and word pair task--were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p laterality in children with a high degree of correlation between the two imaging modalities.

  3. A preliminary diffusional kurtosis imaging study of Parkinson disease: comparison with conventional diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kamagata, Koji; Kamiya, Kouhei; Suzuki, Michimasa; Hori, Masaaki; Yoshida, Mariko; Aoki, Shigeki [Juntendo University School of Medicine, Department of Radiology, Bunkyo-ku, Tokyo (Japan); Tomiyama, Hiroyuki; Hatano, Taku; Motoi, Yumiko; Hattori, Nobutaka [Juntendo University School of Medicine, Department of Neurology, Tokyo (Japan); Abe, Osamu [Nihon University School of Medicine, Department of Radiology, Tokyo (Japan); Shimoji, Keigo [National Center of Neurology and Psychiatry Hospital, Department of Radiology, Tokyo (Japan)

    2014-03-15

    Diffusional kurtosis imaging (DKI) is a more sensitive technique than conventional diffusion tensor imaging (DTI) for assessing tissue microstructure. In particular, it quantifies the microstructural integrity of white matter, even in the presence of crossing fibers. The aim of this preliminary study was to compare how DKI and DTI show white matter alterations in Parkinson disease (PD). DKI scans were obtained with a 3-T magnetic resonance imager from 12 patients with PD and 10 healthy controls matched by age and sex. Tract-based spatial statistics were used to compare the mean kurtosis (MK), mean diffusivity (MD), and fractional anisotropy (FA) maps of the PD patient group and the control group. In addition, a region-of-interest analysis was performed for the area of the posterior corona radiata and superior longitudinal fasciculus (SLF) fiber crossing. FA values in the frontal white matter were significantly lower in PD patients than in healthy controls. Reductions in MK occurred more extensively throughout the brain: in addition to frontal white matter, MK was lower in the parietal, occipital, and right temporal white matter. The MK value of the area of the posterior corona radiata and SLF fiber crossing was also lower in the PD group. DKI detects changes in the cerebral white matter of PD patients more sensitively than conventional DTI. In addition, DKI is useful for evaluating crossing fibers. By providing a sensitive index of brain pathology in PD, DKI may enable improved monitoring of disease progression. (orig.)

  4. Current contribution of diffusion tensor imaging in the evaluation of diffuse axonal injury

    Directory of Open Access Journals (Sweden)

    Daphine Centola Grassi

    Full Text Available ABSTRACT Traumatic brain injury (TBI is the number one cause of death and morbidity among young adults. Moreover, survivors are frequently left with functional disabilities during the most productive years of their lives. One main aspect of TBI pathology is diffuse axonal injury, which is increasingly recognized due to its presence in 40% to 50% of all cases that require hospital admission. Diffuse axonal injury is defined as widespread axonal damage and is characterized by complete axotomy and secondary reactions due to overall axonopathy. These changes can be seen in neuroimaging studies as hemorrhagic focal areas and diffuse edema. However, the diffuse axonal injury findings are frequently under-recognized in conventional neuroimaging studies. In such scenarios, diffuse tensor imaging (DTI plays an important role because it provides further information on white matter integrity that is not obtained with standard magnetic resonance imaging sequences. Extensive reviews concerning the physics of DTI and its use in the context of TBI patients have been published, but these issues are still hazy for many allied-health professionals. Herein, we aim to review the current contribution of diverse state-of-the-art DTI analytical methods to the understanding of diffuse axonal injury pathophysiology and prognosis, to serve as a quick reference for those interested in planning new studies and who are involved in the care of TBI victims. For this purpose, a comprehensive search in Pubmed was performed using the following keywords: “traumatic brain injury”, “diffuse axonal injury”, and “diffusion tensor imaging”.

  5. Magnetic resonance temporal diffusion tensor spectroscopy of disordered anisotropic tissue

    DEFF Research Database (Denmark)

    Nielsen, Jonathan Scharff; Dyrby, Tim Bjørn; Lundell, Henrik

    2018-01-01

    of the oscillating gradient spin echo (OGSE) experiment, giving a basic contrast mechanism closely linked to both the temporal diffusion spectrum and the compartment anisotropy. We demonstrate our new method on post mortem brain tissue and show that we retrieve the correct temporal diffusion tensor spectrum...

  6. Illustrative white matter fiber bundles

    NARCIS (Netherlands)

    Otten, R.J.G.; Vilanova, A.; Wetering, van de H.M.M.

    2010-01-01

    Diffusion Tensor Imaging (DTI) has made feasible the visualization of the fibrous structure of the brain whitematter. In the last decades, several fiber-tracking methods have been developed to reconstruct the fiber tracts fromDTI data. Usually these fiber tracts are shown individually based on some

  7. Image denoising using non linear diffusion tensors

    International Nuclear Information System (INIS)

    Benzarti, F.; Amiri, H.

    2011-01-01

    Image denoising is an important pre-processing step for many image analysis and computer vision system. It refers to the task of recovering a good estimate of the true image from a degraded observation without altering and changing useful structure in the image such as discontinuities and edges. In this paper, we propose a new approach for image denoising based on the combination of two non linear diffusion tensors. One allows diffusion along the orientation of greatest coherences, while the other allows diffusion along orthogonal directions. The idea is to track perfectly the local geometry of the degraded image and applying anisotropic diffusion mainly along the preferred structure direction. To illustrate the effective performance of our model, we present some experimental results on a test and real photographic color images.

  8. Diffusion tensor imaging of the optic tracts in multiple sclerosis: association with retinal thinning and visual disability.

    Science.gov (United States)

    Dasenbrock, Hormuzdiyar H; Smith, Seth A; Ozturk, Arzu; Farrell, Sheena K; Calabresi, Peter A; Reich, Daniel S

    2011-04-01

    Visual disability is common in multiple sclerosis, but its relationship to abnormalities of the optic tracts remains unknown. Because they are only rarely affected by lesions, the optic tracts may represent a good model for assessing the imaging properties of normal-appearing white matter in multiple sclerosis. Whole-brain diffusion tensor imaging was performed on 34 individuals with multiple sclerosis and 26 healthy volunteers. The optic tracts were reconstructed by tractography, and tract-specific diffusion indices were quantified. In the multiple-sclerosis group, peripapillary retinal nerve-fiber-layer thickness and total macular volume were measured by optical coherence tomography, and visual acuity at 100%, 2.5%, and 1.25% contrast was examined. After adjusting for age and sex, optic-tract mean and perpendicular diffusivity were higher (P=.002) in multiple sclerosis. Lower optic-tract fractional anisotropy was correlated with retinal nerve-fiber-layer thinning (r=.51, P=.003) and total-macular-volume reduction (r=.59, P=.002). However, optic-tract diffusion indices were not specifically correlated with visual acuity or with their counterparts in the optic radiation. Optic-tract diffusion abnormalities are associated with retinal damage, suggesting that both may be related to optic-nerve injury, but do not appear to contribute strongly to visual disability in multiple sclerosis. Copyright © 2010 by the American Society of Neuroimaging.

  9. White Matter Compromise of Callosal and Subcortical Fiber Tracts in Children with Autism Spectrum Disorder: A Diffusion Tensor Imaging Study

    Science.gov (United States)

    Shukla, Dinesh K.; Keehn, Brandon; Lincoln, Alan J.; Muller, Ralph-Axel

    2010-01-01

    Objective: Autism spectrum disorder (ASD) is increasingly viewed as a disorder of functional networks, highlighting the importance of investigating white matter and interregional connectivity. We used diffusion tensor imaging (DTI) to examine white matter integrity for the whole brain and for corpus callosum, internal capsule, and middle…

  10. Diffusion Tensor Tractography Reveals Disrupted Structural Connectivity during Brain Aging

    Science.gov (United States)

    Lin, Lan; Tian, Miao; Wang, Qi; Wu, Shuicai

    2017-10-01

    Brain aging is one of the most crucial biological processes that entail many physical, biological, chemical, and psychological changes, and also a major risk factor for most common neurodegenerative diseases. To improve the quality of life for the elderly, it is important to understand how the brain is changed during the normal aging process. We compared diffusion tensor imaging (DTI)-based brain networks in a cohort of 75 healthy old subjects by using graph theory metrics to describe the anatomical networks and connectivity patterns, and network-based statistic (NBS) analysis was used to identify pairs of regions with altered structural connectivity. The NBS analysis revealed a significant network comprising nine distinct fiber bundles linking 10 different brain regions showed altered white matter structures in young-old group compare with middle-aged group (p < .05, family-wise error-corrected). Our results might guide future studies and help to gain a better understanding of brain aging.

  11. Diffusion tensor imaging with direct cytopathological validation: characterisation of decorin treatment in experimental juvenile communicating hydrocephalus.

    Science.gov (United States)

    Aojula, Anuriti; Botfield, Hannah; McAllister, James Patterson; Gonzalez, Ana Maria; Abdullah, Osama; Logan, Ann; Sinclair, Alexandra

    2016-05-31

    In an effort to develop novel treatments for communicating hydrocephalus, we have shown previously that the transforming growth factor-β antagonist, decorin, inhibits subarachnoid fibrosis mediated ventriculomegaly; however decorin's ability to prevent cerebral cytopathology in communicating hydrocephalus has not been fully examined. Furthermore, the capacity for diffusion tensor imaging to act as a proxy measure of cerebral pathology in multiple sclerosis and spinal cord injury has recently been demonstrated. However, the use of diffusion tensor imaging to investigate cytopathological changes in communicating hydrocephalus is yet to occur. Hence, this study aimed to determine whether decorin treatment influences alterations in diffusion tensor imaging parameters and cytopathology in experimental communicating hydrocephalus. Moreover, the study also explored whether diffusion tensor imaging parameters correlate with cellular pathology in communicating hydrocephalus. Accordingly, communicating hydrocephalus was induced by injecting kaolin into the basal cisterns in 3-week old rats followed immediately by 14 days of continuous intraventricular delivery of either human recombinant decorin (n = 5) or vehicle (n = 6). Four rats remained as intact controls and a further four rats served as kaolin only controls. At 14-days post-kaolin, just prior to sacrifice, routine magnetic resonance imaging and magnetic resonance diffusion tensor imaging was conducted and the mean diffusivity, fractional anisotropy, radial and axial diffusivity of seven cerebral regions were assessed by voxel-based analysis in the corpus callosum, periventricular white matter, caudal internal capsule, CA1 hippocampus, and outer and inner parietal cortex. Myelin integrity, gliosis and aquaporin-4 levels were evaluated by post-mortem immunohistochemistry in the CA3 hippocampus and in the caudal brain of the same cerebral structures analysed by diffusion tensor imaging. Decorin significantly

  12. Comparison of Multi-Tensor Diffusion Models' Performance for White Matter Integrity Estimation in Chronic Stroke

    Directory of Open Access Journals (Sweden)

    Olena G. Filatova

    2018-04-01

    Full Text Available Better insight into white matter (WM alterations after stroke onset could help to understand the underlying recovery mechanisms and improve future interventions. MR diffusion imaging enables to assess such changes. Our goal was to investigate the relation of WM diffusion characteristics derived from diffusion models of increasing complexity with the motor function of the upper limb. Moreover, we aimed to evaluate the variation of such characteristics across different WM structures of chronic stroke patients in comparison to healthy subjects. Subjects were scanned with a two b-value diffusion-weighted MRI protocol to exploit multiple diffusion models: single tensor, single tensor with isotropic compartment, bi-tensor model, bi-tensor with isotropic compartment. From each model we derived the mean tract fractional anisotropy (FA, mean (MD, radial (RD and axial (AD diffusivities outside the lesion site based on a WM tracts atlas. Asymmetry of these measures was correlated with the Fugl-Meyer upper extremity assessment (FMA score and compared between patient and control groups. Eighteen chronic stroke patients and eight age-matched healthy individuals participated in the study. Significant correlation of the outcome measures with the clinical scores of stroke recovery was found. The lowest correlation of the corticospinal tract FAasymmetry and FMA was with the single tensor model (r = −0.3, p = 0.2 whereas the other models reported results in the range of r = −0.79 ÷ −0.81 and p = 4E-5 ÷ 8E-5. The corticospinal tract and superior longitudinal fasciculus showed most alterations in our patient group relative to controls. Multiple compartment models yielded superior correlation of the diffusion measures and FMA compared to the single tensor model.

  13. Reconstruction of the arcuate fasciculus for surgical planning in the setting of peritumoral edema using two-tensor unscented Kalman filter tractography.

    Science.gov (United States)

    Chen, Zhenrui; Tie, Yanmei; Olubiyi, Olutayo; Rigolo, Laura; Mehrtash, Alireza; Norton, Isaiah; Pasternak, Ofer; Rathi, Yogesh; Golby, Alexandra J; O'Donnell, Lauren J

    2015-01-01

    Diffusion imaging tractography is increasingly used to trace critical fiber tracts in brain tumor patients to reduce the risk of post-operative neurological deficit. However, the effects of peritumoral edema pose a challenge to conventional tractography using the standard diffusion tensor model. The aim of this study was to present a novel technique using a two-tensor unscented Kalman filter (UKF) algorithm to track the arcuate fasciculus (AF) in brain tumor patients with peritumoral edema. Ten right-handed patients with left-sided brain tumors in the vicinity of language-related cortex and evidence of significant peritumoral edema were retrospectively selected for the study. All patients underwent 3-Tesla magnetic resonance imaging (MRI) including a diffusion-weighted dataset with 31 directions. Fiber tractography was performed using both single-tensor streamline and two-tensor UKF tractography. A two-regions-of-interest approach was applied to perform the delineation of the AF. Results from the two different tractography algorithms were compared visually and quantitatively. Using single-tensor streamline tractography, the AF appeared disrupted in four patients and contained few fibers in the remaining six patients. Two-tensor UKF tractography delineated an AF that traversed edematous brain areas in all patients. The volume of the AF was significantly larger on two-tensor UKF than on single-tensor streamline tractography (p tensor UKF tractography provides the ability to trace a larger volume AF than single-tensor streamline tractography in the setting of peritumoral edema in brain tumor patients.

  14. A Riemannian scalar measure for diffusion tensor images

    NARCIS (Netherlands)

    Astola, L.J.; Fuster, A.; Florack, L.M.J.

    2010-01-01

    We study a well-known scalar quantity in Riemannian geometry, the Ricci scalar, in the context of Diffusion Tensor Imaging (DTI), which is an emerging non-invasive medical imaging modality. We derive a physical interpretation for the Ricci scalar and explore experimentally its significance in DTI.

  15. Fiber orientation measurements by diffusion tensor imaging improve hydrogen-1 magnetic resonance spectroscopy of intramyocellular lipids in human leg muscles.

    Science.gov (United States)

    Valaparla, Sunil K; Gao, Feng; Daniele, Giuseppe; Abdul-Ghani, Muhammad; Clarke, Geoffrey D

    2015-04-01

    Twelve healthy subjects underwent hydrogen-1 magnetic resonance spectroscopy ([Formula: see text]) acquisition ([Formula: see text]), diffusion tensor imaging (DTI) with a [Formula: see text]-value of [Formula: see text], and fat-water magnetic resonance imaging (MRI) using the Dixon method. Subject-specific muscle fiber orientation, derived from DTI, was used to estimate the lipid proton spectral chemical shift. Pennation angles were measured as 23.78 deg in vastus lateralis (VL), 17.06 deg in soleus (SO), and 8.49 deg in tibialis anterior (TA) resulting in a chemical shift between extramyocellular lipids (EMCL) and intramyocellular lipids (IMCL) of 0.15, 0.17, and 0.19 ppm, respectively. IMCL concentrations were [Formula: see text], [Formula: see text], and [Formula: see text] in SO, VL, and TA, respectively. Significant differences were observed in IMCL and EMCL pairwise comparisons in SO, VL, and TA ([Formula: see text]). Strong correlations were observed between total fat fractions from [Formula: see text] and Dixon MRI for VL ([Formula: see text]), SO ([Formula: see text]), and TA ([Formula: see text]). Bland-Altman analysis between fat fractions (FFMRS and FFMRI) showed good agreement with small limits of agreement (LoA): [Formula: see text] (LoA: [Formula: see text] to 0.69%) in VL, [Formula: see text] (LoA: [Formula: see text] to 1.33%) in SO, and [Formula: see text] (LoA: [Formula: see text] to 0.47%) in TA. The results of this study demonstrate the variation in muscle fiber orientation and lipid concentrations in these three skeletal muscle types.

  16. An introduction to diffusion tensor image analysis.

    Science.gov (United States)

    O'Donnell, Lauren J; Westin, Carl-Fredrik

    2011-04-01

    Diffusion tensor magnetic resonance imaging (DTI) is a relatively new technology that is popular for imaging the white matter of the brain. This article provides a basic and broad overview of DTI to enable the reader to develop an intuitive understanding of these types of data, and an awareness of their strengths and weaknesses. Copyright © 2011 Elsevier Inc. All rights reserved.

  17. Retrospective correction of bias in diffusion tensor imaging arising from coil combination mode.

    Science.gov (United States)

    Sakaie, Ken; Lowe, Mark

    2017-04-01

    To quantify and retrospectively correct for systematic differences in diffusion tensor imaging (DTI) measurements due to differences in coil combination mode. Multi-channel coils are now standard among MRI systems. There are several options for combining signal from multiple coils during image reconstruction, including sum-of-squares (SOS) and adaptive combine (AC). This contribution examines the bias between SOS- and AC-derived measures of tissue microstructure and a strategy for limiting that bias. Five healthy subjects were scanned under an institutional review board-approved protocol. Each set of raw image data was reconstructed twice-once with SOS and once with AC. The diffusion tensor was calculated from SOS- and AC-derived data by two algorithms-standard log-linear least squares and an approach that accounts for the impact of coil combination on signal statistics. Systematic differences between SOS and AC in terms of tissue microstructure (axial diffusivity, radial diffusivity, mean diffusivity and fractional anisotropy) were evaluated on a voxel-by-voxel basis. SOS-based tissue microstructure values are systematically lower than AC-based measures throughout the brain in each subject when using the standard tensor calculation method. The difference between SOS and AC can be virtually eliminated by taking into account the signal statistics associated with coil combination. The impact of coil combination mode on diffusion tensor-based measures of tissue microstructure is statistically significant but can be corrected retrospectively. The ability to do so is expected to facilitate pooling of data among imaging protocols. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. White matter injury in newborns with congenital heart disease: a diffusion tensor imaging study.

    Science.gov (United States)

    Mulkey, Sarah B; Ou, Xiawei; Ramakrishnaiah, Raghu H; Glasier, Charles M; Swearingen, Christopher J; Melguizo, Maria S; Yap, Vivien L; Schmitz, Michael L; Bhutta, Adnan T

    2014-09-01

    Brain injury is observed on cranial magnetic resonance imaging preoperatively in up to 50% of newborns with congenital heart disease. Newer imaging techniques such as diffusion tensor imaging provide sensitive measures of the white matter integrity. The objective of this study was to evaluate the diffusion tensor imaging analysis technique of tract-based spatial statistics in newborns with congenital heart disease. Term newborns with congenital heart disease who would require surgery at less than 1 month of age were prospectively enrolled (n = 19). Infants underwent preoperative and postoperative brain magnetic resonance imaging with diffusion tensor imaging. Tract-based spatial statistics, an objective whole-brain diffusion tensor imaging analysis technique, was used to determine differences in white matter fractional anisotropy between infant groups. Term control infants were also compared with congenital heart disease infants. Postmenstrual age was equivalent between congenital heart disease infant groups and between congenital heart disease and control infants. Ten infants had preoperative brain injury, either infarct or white matter injury, by conventional brain magnetic resonance imaging. The technique of tract-based spatial statistics showed significantly lower fractional anisotropy (P tensor imaging analysis technique that may have better sensitivity in detecting white matter injury compared with conventional brain magnetic resonance imaging in term newborns with congenital heart disease. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Limb apraxia in a patient with cerebral infarct: diffusion tensor tractography study.

    Science.gov (United States)

    Hong, Ji Heon; Lee, Jun; Cho, Yoon Woo; Byun, Woo Mok; Cho, Hee Kyung; Son, Su Min; Jang, Sung Ho

    2012-01-01

    We report on a patient with ideomotor apraxia (IMA) and limb-kinetic apraxia (LKA) following cerebral infarct, which demonstrated neural tract injuries by diffusion tensor tractography (DTT). A 67-year-old male was diagnosed as cerebral infarct in the left frontal cortex (anterior portion of the precentral gyrus and prefrontal cortex) and centrum semiovale. The patient presented with severe paralysis of the right upper extremity and mild weakness of the right lower extremity at onset. At the time of DTT scanning (5 months after onset), the patient was able to move all joint muscles of the right upper extremity against gravity, except for the finger extensors, which he could extend partially against gravity. The patient showed intact ideational plan for motor performance; however, his movements were slow, clumsy, and mutilated when executing grasp-release movements of his affected hand. The patient's score on the ideomotor apraxia test was 20 (cut-off score < 32). DTTs for premotor cortex fibers, supplementary motor area fibers, and superior longitudinal fasciculus of the left hemisphere showed partial injuries, compared with those of the right side, and these injuries appeared to be responsible for IMA and LKA in this patient.

  20. Diffusion Properties and 3D Architecture of Human Lower Leg Muscles Assessed with Ultra-High-Field-Strength Diffusion-Tensor MR Imaging and Tractography: Reproducibility and Sensitivity to Sex Difference and Intramuscular Variability.

    Science.gov (United States)

    Fouré, Alexandre; Ogier, Augustin C; Le Troter, Arnaud; Vilmen, Christophe; Feiweier, Thorsten; Guye, Maxime; Gondin, Julien; Besson, Pierre; Bendahan, David

    2018-05-01

    Purpose To demonstrate the reproducibility of the diffusion properties and three-dimensional structural organization measurements of the lower leg muscles by using diffusion-tensor imaging (DTI) assessed with ultra-high-field-strength (7.0-T) magnetic resonance (MR) imaging and tractography of skeletal muscle fibers. On the basis of robust statistical mapping analyses, this study also aimed at determining the sensitivity of the measurements to sex difference and intramuscular variability. Materials and Methods All examinations were performed with ethical review board approval; written informed consent was obtained from all volunteers. Reproducibility of diffusion tensor indexes assessment including eigenvalues, mean diffusivity, and fractional anisotropy (FA) as well as muscle volume and architecture (ie, fiber length and pennation angle) were characterized in lower leg muscles (n = 8). Intramuscular variability and sex differences were characterized in young healthy men and women (n = 10 in each group). Student t test, statistical parametric mapping, correlation coefficients (Spearman rho and Pearson product-moment) and coefficient of variation (CV) were used for statistical data analysis. Results High reproducibility of measurements (mean CV ± standard deviation, 4.6% ± 3.8) was determined in diffusion properties and architectural parameters. Significant sex differences were detected in FA (4.2% in women for the entire lower leg; P = .001) and muscle volume (21.7% in men for the entire lower leg; P = .008), whereas architecture parameters were almost identical across sex. Additional differences were found independently of sex in diffusion properties and architecture along several muscles of the lower leg. Conclusion The high-spatial-resolution DTI assessed with 7.0-T MR imaging allows a reproducible assessment of structural organization of superficial and deep muscles, giving indirect information on muscle function. © RSNA, 2018 Online supplemental material is

  1. Combining voxel-based morphometry and diffusion tensor imaging to detect age-related brain changes.

    Science.gov (United States)

    Lehmbeck, Jan T; Brassen, Stefanie; Weber-Fahr, Wolfgang; Braus, Dieter F

    2006-04-03

    The present study combined optimized voxel-based morphometry and diffusion tensor imaging to detect age-related brain changes. We compared grey matter density maps (grey matter voxel-based morphometry) and white matter fractional anisotropy maps (diffusion tensor imaging-voxel-based morphometry) between two groups of 17 younger and 17 older women. Older women exhibited reduced white matter fractional anisotropy as well as decreased grey matter density most prominently in the frontal, limbic, parietal and temporal lobes. A discriminant analysis identified four frontal and limbic grey and white matter areas that separated the two groups most effectively. We conclude that grey matter voxel-based morphometry and diffusion tensor imaging voxel-based morphometry are well suited for the detection of age-related changes and their combination provides high accuracy when detecting the neural correlates of aging.

  2. Diffusion-tensor MR imaging of gray and white matter development during normal human brain maturation.

    Science.gov (United States)

    Mukherjee, Pratik; Miller, Jeffrey H; Shimony, Joshua S; Philip, Joseph V; Nehra, Deepika; Snyder, Abraham Z; Conturo, Thomas E; Neil, Jeffrey J; McKinstry, Robert C

    2002-10-01

    Conventional MR imaging findings of human brain development are thought to result from decreasing water content, increasing macromolecular concentration, and myelination. We use diffusion-tensor MR imaging to test theoretical models that incorporate hypotheses regarding how these maturational processes influence water diffusion in developing gray and white matter. Experimental data were derived from diffusion-tensor imaging of 167 participants, ages 31 gestational weeks to 11 postnatal years. An isotropic diffusion model was applied to the gray matter of the basal ganglia and thalamus. A model that assumes changes in the magnitude of diffusion while maintaining cylindrically symmetric anisotropy was applied to the white matter of the corpus callosum and internal capsule. Deviations of the diffusion tensor from the ideal model predictions, due to measurement noise, were estimated by using Monte Carlo simulations. Developing gray matter of the basal ganglia and developing white matter of the internal capsule and corpus callosum largely conformed to theory, with only small departures from model predictions in older children. However, data from the thalamus substantially diverged from predicted values, with progressively larger deviations from the model with increasing participant age. Changes in water diffusion during maturation of central gray and white matter structures can largely be explained by theoretical models incorporating simple assumptions regarding the influence of brain water content and myelination, although deviations from theory increase as the brain matures. Diffusion-tensor MR imaging is a powerful method for studying the process of brain development, with both scientific and clinical applications.

  3. The effects of noise over the complete space of diffusion tensor shape.

    Science.gov (United States)

    Gahm, Jin Kyu; Kindlmann, Gordon; Ennis, Daniel B

    2014-01-01

    Diffusion tensor magnetic resonance imaging (DT-MRI) is a technique used to quantify the microstructural organization of biological tissues. Multiple images are necessary to reconstruct the tensor data and each acquisition is subject to complex thermal noise. As such, measures of tensor invariants, which characterize components of tensor shape, derived from the tensor data will be biased from their true values. Previous work has examined this bias, but over a narrow range of tensor shape. Herein, we define the mathematics for constructing a tensor from tensor invariants, which permits an intuitive and principled means for building tensors with a complete range of tensor shape and salient microstructural properties. Thereafter, we use this development to evaluate by simulation the effects of noise on characterizing tensor shape over the complete space of tensor shape for three encoding schemes with different SNR and gradient directions. We also define a new framework for determining the distribution of the true values of tensor invariants given their measures, which provides guidance about the confidence the observer should have in the measures. Finally, we present the statistics of tensor invariant estimates over the complete space of tensor shape to demonstrate how the noise sensitivity of tensor invariants varies across the space of tensor shape as well as how the imaging protocol impacts measures of tensor invariants. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Diffusion Tensor Imaging for the Differentiation of Microangiopathy, Infarction and Perfusion-Diffusion Mismatch Lesions

    International Nuclear Information System (INIS)

    Ha, Dong Ho; Choi, Sun Seob; Kang, Myong Jin; Lee, Jin Hwa; Yoon, Seong Kuk; Nam, Kyung Jin

    2009-01-01

    This study was designed to evaluate the usefulness of diffusion tensor imaging (DTI) and the DTI indices for differentiating between microangiopathy lesions, acute infarction lesions and perfusion-diffusion mismatch areas. DTI was performed in 35 patients with the use of a 1.5 Tesla MRI system. The MRI parameters were as follows: a spin echo EPI sequence with a bvalue = 1000 s/mm 2 , 25 diffusion directions, a repetition time of 8400 msec, an echo time of 75 msec, a matrix size of 128 x 128, a FOV of 22 cm and a 4 mm slice thickness. From the diffusion tensor images, the apparent diffusion coefficient (ADC), fractional anisotropy (FA), volume ratio (VR), relative anisotropy (RA), anisotropy index (AI), exponential ADC (eADC) and magnitude diffusion coefficient (MDC) were measured for the contra-lateral normal area (28 cases), the microangiopathy lesions (10 cases), the infarction lesions (17 cases) and the perfusion-diffusion mismatch area (8 cases). As compared to the normal area, the microangiopathy lesions showed increased ADC and MDC values and decreased FA, VR, RA, AI and eADC values. The infarction lesions showed increased VR, RA and eADC values, a normal FA, a decreased AI and decreased ADC and MDC values. The mismatch area showed a similar pattern as that for the microangiopathy lesions; however, the differences were not prominent, with an increase of the ADC and MDC values and a decrease of FA, VR, RA, AI and eADC values. The DTI indices could have a role in making the differential diagnosis of microangiopathy, acute infarction and perfusion-diffusion mismatch lesions

  5. Changes in Parahippocampal White Matter Integrity in Amnestic Mild Cognitive Impairment: A Diffusion Tensor Imaging Study

    Directory of Open Access Journals (Sweden)

    E. J. Rogalski

    2009-01-01

    Full Text Available In the present study, changes in the parahippocampal white matter (PWM, in the region that includes the perforant path, were investigated, in vivo, in 14 individuals with amnestic mild cognitive impairment (aMCI compared to 14 elderly controls with no cognitive impairment (NCI. For this purpose, (1 volumetry; (2 diffusion tensor imaging (DTI derived measures of mean diffusivity (MD and fractional anisotropy (FA; and (3 tractography were used. In addition, regression models were utilized to examine the association of PWM measurements with memory decline. The results from this study confirm previous findings in our laboratory and others, showing that compared to controls, individuals with aMCI have PWM volume loss. In addition to volume reduction, participants with aMCI demonstrated a significant increase in MD, but no difference in FA, both in the PWM region and in fibers modeled to pass through the PWM region. Further, the DTI metric of MD was associated with declarative memory performance, suggesting it may be a sensitive marker for memory dysfunction. These results indicate that there is general tissue loss and degradation (decreased volume; increased MD in individuals with aMCI compared to older people with normal cognitive function. However, the microstructural organization of remaining fibers, as determined by measures of anisotropic diffusion, is not significantly different from that of controls.

  6. Novel region of interest interrogation technique for diffusion tensor imaging analysis in the canine brain.

    Science.gov (United States)

    Li, Jonathan Y; Middleton, Dana M; Chen, Steven; White, Leonard; Ellinwood, N Matthew; Dickson, Patricia; Vite, Charles; Bradbury, Allison; Provenzale, James M

    2017-08-01

    Purpose We describe a novel technique for measuring diffusion tensor imaging metrics in the canine brain. We hypothesized that a standard method for region of interest placement could be developed that is highly reproducible, with less than 10% difference in measurements between raters. Methods Two sets of canine brains (three seven-week-old full-brains and two 17-week-old single hemispheres) were scanned ex-vivo on a 7T small-animal magnetic resonance imaging system. Strict region of interest placement criteria were developed and then used by two raters to independently measure diffusion tensor imaging metrics within four different white-matter regions within each specimen. Average values of fractional anisotropy, radial diffusivity, and the three eigenvalues (λ1, λ2, and λ3) within each region in each specimen overall and within each individual image slice were compared between raters by calculating the percentage difference between raters for each metric. Results The mean percentage difference between raters for all diffusion tensor imaging metrics when pooled by each region and specimen was 1.44% (range: 0.01-5.17%). The mean percentage difference between raters for all diffusion tensor imaging metrics when compared by individual image slice was 2.23% (range: 0.75-4.58%) per hemisphere. Conclusion Our results indicate that the technique described is highly reproducible, even when applied to canine specimens of differing age, morphology, and image resolution. We propose this technique for future studies of diffusion tensor imaging analysis in canine brains and for cross-sectional and longitudinal studies of canine brain models of human central nervous system disease.

  7. MR diffusion tensor analysis of schizophrenic brain using statistical parametric mapping

    International Nuclear Information System (INIS)

    Yamada, Haruyasu; Abe, Osamu; Kasai, Kiyoto

    2005-01-01

    The purpose of this study is to investigate diffusion anisotropy in the schizophrenic brain by voxel-based analysis of diffusion tensor imaging (DTI), using statistical parametric mapping (SPM). We studied 33 patients with schizophrenia diagnosed by diagnostic and statistical manual of mental disorders (DSM)-IV criteria and 42 matched controls. The data was obtained with a 1.5 T MRI system. We used single-shot spin-echo planar sequences (repetition time/echo time (TR/TE)=5000/102 ms, 5 mm slice thickness and 1.5 mm gap, field of view (FOV)=21 x 21 cm 2 , number of excitation (NEX)=4, 128 x 128 pixel matrix) for diffusion tensor acquisition. Diffusion gradients (b-value of 500 or 1000 s/mm 2 ) were applied on two axes simultaneously. Diffusion properties were measured along 6 non-linear directions. The structural distortion induced by the large diffusion gradients was corrected, based on each T 2 -weighted echo-planar image (b=0 s/mm 2 ). The fractional anisotropy (FA) maps were generated on a voxel-by-voxel basis. T 2 -weighted echo-planar images were then segmented into gray matter, white matter, and cerebrospinal fluid, using SPM (Wellcome Department of Imaging, University College London, UK). All apparent diffusion coefficient (ADC) and FA maps in native space were transformed to the stereotactic space by registering each of the images to the same template image. The normalized data was smoothed and analyzed using SPM. The significant FA decrease in the patient group was found in the uncinate fasciculus, parahippocampal white matter, anterior cingulum and other areas (corrected p<0.05). No significant increased region was noted. Our results may reflect reduced diffusion anisotropy of the white matter pathway of the limbic system as shown by the decreased FA. Manual region-of-interest analysis is usually more sensitive than voxel-based analysis, but it is subjective and difficult to set with anatomical reproducibility. Voxel-based analysis of the diffusion tensor

  8. In utero diffusion tensor imaging of the fetal brain: A reproducibility study.

    Science.gov (United States)

    Jakab, András; Tuura, Ruth; Kellenberger, Christian; Scheer, Ianina

    2017-01-01

    Our purpose was to evaluate the within-subject reproducibility of in utero diffusion tensor imaging (DTI) metrics and the visibility of major white matter structures. Images for 30 fetuses (20-33. postmenstrual weeks, normal neurodevelopment: 6 cases, cerebral pathology: 24 cases) were acquired on 1.5 T or 3.0 T MRI. DTI with 15 diffusion-weighting directions was repeated three times for each case, TR/TE: 2200/63 ms, voxel size: 1 ∗ 1 mm, slice thickness: 3-5 mm, b-factor: 700 s/mm 2 . Reproducibility was evaluated from structure detectability, variability of DTI measures using the coefficient of variation (CV), image correlation and structural similarity across repeated scans for six selected structures. The effect of age, scanner type, presence of pathology was determined using Wilcoxon rank sum test. White matter structures were detectable in the following percentage of fetuses in at least two of the three repeated scans: corpus callosum genu 76%, splenium 64%, internal capsule, posterior limb 60%, brainstem fibers 40% and temporooccipital association pathways 60%. The mean CV of DTI metrics ranged between 3% and 14.6% and we measured higher reproducibility in fetuses with normal brain development. Head motion was negatively correlated with reproducibility, this effect was partially ameliorated by motion-correction algorithm using image registration. Structures on 3.0 T had higher variability both with- and without motion correction. Fetal DTI is reproducible for projection and commissural bundles during mid-gestation, however, in 16-30% of the cases, data were corrupted by artifacts, resulting in impaired detection of white matter structures. To achieve robust results for the quantitative analysis of diffusivity and anisotropy values, fetal-specific image processing is recommended and repeated DTI is needed to ensure the detectability of fiber pathways.

  9. Data quality in diffusion tensor imaging studies of the preterm brain: a systematic review

    OpenAIRE

    Pieterman, Kay; Plaisier, Annemarie; Govaert, Paul; Leemans, Alexander; Lequin, Maarten H.; Dudink, Jeroen

    2015-01-01

    Background To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount. Objective To review the literature to evaluate acquisition and processing methodology in diffusion tensor imaging studies of preterm infants. Materials and methods We searched the Embase, Medline, Web of Science and Cochrane databases for relevant papers published between 20...

  10. Diffusion tensor imaging for target volume definition in glioblastoma multiforme

    Energy Technology Data Exchange (ETDEWEB)

    Berberat, Jatta; Remonda, Luca [Cantonal Hospital, Department of Neuro-radiology, Aarau (Switzerland); McNamara, Jane; Rogers, Susanne [Cantonal Hospital, Department of Radiation Oncology, Aarau (Switzerland); Bodis, Stephan [Cantonal Hospital, Department of Radiation Oncology, Aarau (Switzerland); University Hospital, Department of Radiation Oncology, Zurich (Switzerland)

    2014-10-15

    Diffusion tensor imaging (DTI) is an MR-based technique that may better detect the peritumoural region than MRI. Our aim was to explore the feasibility of using DTI for target volume delineation in glioblastoma patients. MR tensor tracts and maps of the isotropic (p) and anisotropic (q) components of water diffusion were coregistered with CT in 13 glioblastoma patients. An in-house image processing program was used to analyse water diffusion in each voxel of interest in the region of the tumour. Tumour infiltration was mapped according to validated criteria and contralateral normal brain was used as an internal control. A clinical target volume (CTV) was generated based on the T{sub 1}-weighted image obtained using contrast agent (T{sub 1Gd}), tractography and the infiltration map. This was compared to a conventional T{sub 2}-weighted CTV (T{sub 2}-w CTV). Definition of a diffusion-based CTV that included the adjacent white matter tracts proved highly feasible. A statistically significant difference was detected between the DTI-CTV and T{sub 2}-w CTV volumes (p < 0.005, t = 3.480). As the DTI-CTVs were smaller than the T{sub 2}-w CTVs (tumour plus peritumoural oedema), the pq maps were not simply detecting oedema. Compared to the clinical planning target volume (PTV), the DTI-PTV showed a trend towards volume reduction. These diffusion-based volumes were smaller than conventional volumes, yet still included sites of tumour recurrence. Extending the CTV along the abnormal tensor tracts in order to preserve coverage of the likely routes of dissemination, whilst sparing uninvolved brain, is a rational approach to individualising radiotherapy planning for glioblastoma patients. (orig.) [German] Die Diffusions-Tensor-Bildgebung (DTI) ist eine MR-Technik, die dank der Erfassung des peritumoralen Bereichs eine Verbesserung bezueglich MRI bringt. Unser Ziel war die Pruefung der Machbarkeit der Verwendung der DTI fuer die Zielvolumenabgrenzung fuer Patienten mit

  11. Diffusion tensor tractography of the arcuate fasciculus in patients with brain tumors: Comparison between deterministic and probabilistic models.

    Science.gov (United States)

    Li, Zhixi; Peck, Kyung K; Brennan, Nicole P; Jenabi, Mehrnaz; Hsu, Meier; Zhang, Zhigang; Holodny, Andrei I; Young, Robert J

    2013-02-01

    The purpose of this study was to compare the deterministic and probabilistic tracking methods of diffusion tensor white matter fiber tractography in patients with brain tumors. We identified 29 patients with left brain tumors probabilistic method based on an extended Monte Carlo Random Walk algorithm. Tracking was controlled using two ROIs corresponding to Broca's and Wernicke's areas. Tracts in tumoraffected hemispheres were examined for extension between Broca's and Wernicke's areas, anterior-posterior length and volume, and compared with the normal contralateral tracts. Probabilistic tracts displayed more complete anterior extension to Broca's area than did FACT tracts on the tumor-affected and normal sides (p probabilistic tracts than FACT tracts (p probabilistic tracts than FACT tracts (p = 0.01). Probabilistic tractography reconstructs the arcuate fasciculus more completely and performs better through areas of tumor and/or edema. The FACT algorithm tends to underestimate the anterior-most fibers of the arcuate fasciculus, which are crossed by primary motor fibers.

  12. Validation of diffusion tensor MRI measurements of cardiac microstructure with structure tensor synchrotron radiation imaging.

    Science.gov (United States)

    Teh, Irvin; McClymont, Darryl; Zdora, Marie-Christine; Whittington, Hannah J; Davidoiu, Valentina; Lee, Jack; Lygate, Craig A; Rau, Christoph; Zanette, Irene; Schneider, Jürgen E

    2017-03-10

    Diffusion tensor imaging (DTI) is widely used to assess tissue microstructure non-invasively. Cardiac DTI enables inference of cell and sheetlet orientations, which are altered under pathological conditions. However, DTI is affected by many factors, therefore robust validation is critical. Existing histological validation is intrinsically flawed, since it requires further tissue processing leading to sample distortion, is routinely limited in field-of-view and requires reconstruction of three-dimensional volumes from two-dimensional images. In contrast, synchrotron radiation imaging (SRI) data enables imaging of the heart in 3D without further preparation following DTI. The objective of the study was to validate DTI measurements based on structure tensor analysis of SRI data. One isolated, fixed rat heart was imaged ex vivo with DTI and X-ray phase contrast SRI, and reconstructed at 100 μm and 3.6 μm isotropic resolution respectively. Structure tensors were determined from the SRI data and registered to the DTI data. Excellent agreement in helix angles (HA) and transverse angles (TA) was observed between the DTI and structure tensor synchrotron radiation imaging (STSRI) data, where HA DTI-STSRI  = -1.4° ± 23.2° and TA DTI-STSRI  = -1.4° ± 35.0° (mean ± 1.96 standard deviation across all voxels in the left ventricle). STSRI confirmed that the primary eigenvector of the diffusion tensor corresponds with the cardiomyocyte long-axis across the whole myocardium. We have used STSRI as a novel and high-resolution gold standard for the validation of DTI, allowing like-with-like comparison of three-dimensional tissue structures in the same intact heart free of distortion. This represents a critical step forward in independently verifying the structural basis and informing the interpretation of cardiac DTI data, thereby supporting the further development and adoption of DTI in structure-based electro-mechanical modelling and routine clinical

  13. Global diffusion tensor imaging derived metrics differentiate glioblastoma multiforme vs. normal brains by using discriminant analysis: introduction of a novel whole-brain approach.

    Science.gov (United States)

    Roldan-Valadez, Ernesto; Rios, Camilo; Cortez-Conradis, David; Favila, Rafael; Moreno-Jimenez, Sergio

    2014-06-01

    Histological behavior of glioblastoma multiforme suggests it would benefit more from a global rather than regional evaluation. A global (whole-brain) calculation of diffusion tensor imaging (DTI) derived tensor metrics offers a valid method to detect the integrity of white matter structures without missing infiltrated brain areas not seen in conventional sequences. In this study we calculated a predictive model of brain infiltration in patients with glioblastoma using global tensor metrics. Retrospective, case and control study; 11 global DTI-derived tensor metrics were calculated in 27 patients with glioblastoma multiforme and 34 controls: mean diffusivity, fractional anisotropy, pure isotropic diffusion, pure anisotropic diffusion, the total magnitude of the diffusion tensor, linear tensor, planar tensor, spherical tensor, relative anisotropy, axial diffusivity and radial diffusivity. The multivariate discriminant analysis of these variables (including age) with a diagnostic test evaluation was performed. The simultaneous analysis of 732 measures from 12 continuous variables in 61 subjects revealed one discriminant model that significantly differentiated normal brains and brains with glioblastoma: Wilks' λ = 0.324, χ(2) (3) = 38.907, p tensor and linear tensor. These metrics might be clinically applied for diagnosis, follow-up, and the study of other neurological diseases.

  14. Diffusion tensor imaging (DTI) and tractography of the brachial plexus: feasibility and initial experience in neoplastic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Maria Isabel; Nguyen, Duy; Delavelle, Jacqueline [Geneva University Hospital, Department of Neuroradiology, DISIM, Geneve 14 (Switzerland); Viallon, Magalie [Geneva University Hospital and University of Geneva, Radiology, Geneva (Switzerland); Becker, Minerva [Geneva University Hospital and University of Geneva, Unit of Head and Neck Radiology, Geneva (Switzerland)

    2010-03-15

    The objective of this study was to assess the feasibility and potential clinical applications of diffusion tensor imaging (DTI) and tractography in the normal and pathologic brachial plexus prospectively. Six asymptomatic volunteers and 12 patients with symptoms related to the brachial plexus underwent DTI on a 1.5T system in addition to the routine anatomic plexus imaging protocol. Maps of the apparent diffusion coefficient (ADC) and of fractional anisotropy (FA), as well as tractography of the brachial plexus were obtained. Images were evaluated by two experienced neuroradiologists in a prospective fashion. Three patients underwent surgery, and nine patients underwent conservative medical treatment. Reconstructed DTI (17/18) were of good quality (one case could not be reconstructed due to artifacts). In all volunteers and in 11 patients, the roots and the trunks were clearly delineated with tractography. Mean FA and mean ADC values were as follows: 0.30{+-}0.079 and 1.70{+-}0.35 mm{sup 2}/s in normal fibers, 0.22{+-}0.04 and 1.49{+-}0.49 mm{sup 2}/s in benign neurogenic tumors, and 0.24{+-}0.08 and 1.51{+-}0.52 mm{sup 2}/s in malignant tumors, respectively. Although there was no statistically significant difference in FA and ADC values of normal fibers and fibers at the level of pathology, tractography revealed major differences regarding fiber architecture. In benign neurogenic tumors (n=4), tractography revealed fiber displacement alone (n=2) or fiber displacement and encasement by the tumor (n=2), whereas in the malignant tumors, either fiber disruption/destruction with complete disorganization (n=6) or fiber displacement (n=1) were seen. In patients with fiber displacement alone, surgery confirmed the tractography findings, and excision was successful without sequelae. Our preliminary data suggest that DTI with tractography is feasible in a clinical routine setting. DTI may demonstrate normal tracts, tract displacement, deformation, infiltration, disruption

  15. Diffusion tensor imaging (DTI) and tractography of the brachial plexus: feasibility and initial experience in neoplastic conditions

    International Nuclear Information System (INIS)

    Vargas, Maria Isabel; Nguyen, Duy; Delavelle, Jacqueline; Viallon, Magalie; Becker, Minerva

    2010-01-01

    The objective of this study was to assess the feasibility and potential clinical applications of diffusion tensor imaging (DTI) and tractography in the normal and pathologic brachial plexus prospectively. Six asymptomatic volunteers and 12 patients with symptoms related to the brachial plexus underwent DTI on a 1.5T system in addition to the routine anatomic plexus imaging protocol. Maps of the apparent diffusion coefficient (ADC) and of fractional anisotropy (FA), as well as tractography of the brachial plexus were obtained. Images were evaluated by two experienced neuroradiologists in a prospective fashion. Three patients underwent surgery, and nine patients underwent conservative medical treatment. Reconstructed DTI (17/18) were of good quality (one case could not be reconstructed due to artifacts). In all volunteers and in 11 patients, the roots and the trunks were clearly delineated with tractography. Mean FA and mean ADC values were as follows: 0.30±0.079 and 1.70±0.35 mm 2 /s in normal fibers, 0.22±0.04 and 1.49±0.49 mm 2 /s in benign neurogenic tumors, and 0.24±0.08 and 1.51±0.52 mm 2 /s in malignant tumors, respectively. Although there was no statistically significant difference in FA and ADC values of normal fibers and fibers at the level of pathology, tractography revealed major differences regarding fiber architecture. In benign neurogenic tumors (n=4), tractography revealed fiber displacement alone (n=2) or fiber displacement and encasement by the tumor (n=2), whereas in the malignant tumors, either fiber disruption/destruction with complete disorganization (n=6) or fiber displacement (n=1) were seen. In patients with fiber displacement alone, surgery confirmed the tractography findings, and excision was successful without sequelae. Our preliminary data suggest that DTI with tractography is feasible in a clinical routine setting. DTI may demonstrate normal tracts, tract displacement, deformation, infiltration, disruption, and disorganization of

  16. Assessment of axonal degeneration in Alzheimer's disease with diffusion tensor MRI; Diffusion tensor imaging zur Erfassung axonaler Degeneration bei Morbus Alzheimer

    Energy Technology Data Exchange (ETDEWEB)

    Stahl, R. [Institut fuer Klinische Radiologie - Grosshadern, Klinikum der Universitaet Muenchen (Germany); Institut fuer Klinische Radiologie - Grosshadern, Klinikum der Universitaet Muenchen, Marchioninistr. 15, 81377, Muenchen (Germany); Dietrich, O.; Reiser, M.F.; Schoenberg, S.O. [Institut fuer Klinische Radiologie - Grosshadern, Klinikum der Universitaet Muenchen (Germany); Teipel, S.; Hampel, H. [Klinik fuer Psychiatrie und Psychotherapie, Klinikum der Universitaet Muenchen (Germany)

    2003-07-01

    Alzheimer disease (AD) causes cortical degeneration with subsequent degenerative changes of the white matter. The aim of this study was to investigate the extent of white matter tissue damage of patients with Alzheimer's disease in comparison with healthy subjects using diffusion tensor MRI (DTI). The value of integrated parallel imaging techniques (iPAT) for reduction of image distortion was assessed. We studied 9 patients with mild AD and 10 age and gender matched healthy controls. DTI brain scans were obtained on a 1.5 tesla system (Siemens Magnetom Sonata) using parallel imaging (iPAT) and an EPI diffusion sequence with TE/TR 71 ms/6000 ms. We used an 8-element head coil and a GRAPPA reconstruction algorithm with an acceleration factor of 2. From the tensor, the mean diffusivity (D), the fractional anisotropy (FA), and the relative anisotropy (RA) of several white matter regions were determined. FA was significantly lower (p <0,05) in the white matter of the genu of corpus callosum from patients with AD than in the corresponding regions from healthy controls. There was a trend observed for slightly higher ADC values in the AD group (p=0,06). No significant changes were observed in the regions of the splenium, internal capsule, pericallosal areas, frontal, temporal, parietal, and occipital lobe. The images obtained with iPAT contained substantially less susceptibility artefacts and were less distorted than images acquired with non-parallel imaging technique. DTI is a method with potential to assess early stages of white matter damage in vivo. The altered FA and ADC values in the genu of corpus callosum of patients with AD presumably reflect the microscopic white matter degeneration. Acquisition time can be reduced by iPAT methods with less image distortion from susceptibility artefacts resulting in a more accurate calculation of the diffusion tensor. (orig.) [German] Bei der Alzheimer-Erkrankung (AD) kommt es zur kortikalen Degeneration und sekundaer zu

  17. Diffusion tensor imaging of spinal cord parenchyma lesion in rat with chronic spinal cord injury.

    Science.gov (United States)

    Zhao, Can; Rao, Jia-Sheng; Pei, Xiao-Jiao; Lei, Jian-Feng; Wang, Zhan-Jing; Zhao, Wen; Wei, Rui-Han; Yang, Zhao-Yang; Li, Xiao-Guang

    2018-04-01

    Adequate evaluation of spinal cord parenchyma and accurate identification of injury range are considered two premises for the research and treatment of chronic spinal cord injury (SCI). Diffusion tensor imaging (DTI) provides information about water diffusion in spinal cord, and thus makes it possible to realize these premises. In this study, we conducted magnetic resonance imaging (MRI) for Wistar rats 84days after spinal cord contusion. DTI metrics including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) from different positions of the injured cord were collected, analyzed, and compared with the histological results and locomotor outcomes. Moreover, we performed fiber tractography, and examined the difference in cavity percentage obtained respectively via conventional MRI, DTI and histology. Results showed that the chronic SCI rats had the largest changes of all DTI metrics at the epicenter; the farther away from the epicenter, the smaller the variation. FA, AD and RD were all influenced by SCI in a greater space range than MD. The good consistency of FA values and histological results in specific regions evidenced FA's capability of reflecting Wallerian degeneration after SCI. DTI metrics at the epicenter in ventral funiculus also showed a close correlation with the BBB scores. Additionally, supported by the histological results, DTI enables a more accurate measurement of cavity percentage compared to the conventional MRI. DTI parameters might comprehensively reflect the post-SCI pathological status of spinal cord parenchyma at the epicenter and distal parts during the chronic stage, while showing good consistency with locomotor performance. DTI combined with tractography could intuitively display the distribution of spared fibers after SCI and accurately provide information such as cavity area. This may shed light on the research and treatment of chronic SCI. Copyright © 2017 Elsevier Inc. All rights

  18. Assessment of degradation of the selected projectile, commissural and association brain fibers in patients with Alzheimers disease on diffusion tensor MR imaging

    International Nuclear Information System (INIS)

    Szewczyk, P.; Zimny, A.; Sasiadek, M.; Trypka, E.; Wojtynska, R.; Leszek, J.

    2010-01-01

    Background: Pathological examinations and the increasingly popular diffusion tensor imaging (DTI) show that in Alzheimers disease (AD), the pathology involves not only the cortical and hippocampal structures, but also the white matter of the brain. DTI is a well recognized technique for evaluation of the integrity of white matter fibers. The aim of this study was to assess with the use of DTI some selected brain tracts in patients with AD, as well as to analyze the severity and distribution of the identified changes. Material/Methods: Thirty-five patients with AD (mean age of 71.6 years, MMSE 17.6), and a control group of 15 healthy volunteers (mean age of 69.1 years, MMSE 29.8) were enrolled in the study. All patients were subjected to a thorough psychiatric examination and psychological tests. DTI examinations (TE 8500, TR 100) were performed using a 1.5 T MR scanner. Fractional anisotropy (FA) measurements in the selected areas of interest (ROI) of the white matter fibers were performed under the control of color FA maps. The following fibers were evaluated - the middle cerebellar peduncles (MCP), the inferior longitudinal fasciculi (ILF), inferior frontooccipital fasciculi (IFO), genu (GCC) and splenium of the corpus callosum (SCC), posterior limbs of internal capsules (PLIC), superior longitudinal fasciculi (SLF) and posterior cingula (CG). Results: There was a statistically significant decrease in FA in patients with AD, comparing to the control group. It was particularly strongly expressed in both CG (P < 0.0001), followed by both ILF, right IFO, and left SLF. Less pronounced changes were found in GCC, SCC, and left IFO. In both PLICs and MCPs and in the right SLF, there was no significant change of FA. Conclusions: In Alzheimers disease, there is a significant decrease in FA, which suggests degradation of the majority of the assessed white matter tracts. Distribution of these changes is not uniform. They involve the selected association fibers mainly and

  19. Diffusion Tensor Imaging: Application to the Study of the Developing Brain

    Science.gov (United States)

    Cascio, Carissa J.; Gerig, Guido; Piven, Joseph

    2007-01-01

    Objective: To provide an overview of diffusion tensor imaging (DTI) and its application to the study of white matter in the developing brain in both healthy and clinical samples. Method: The development of DTI and its application to brain imaging of white matter tracts is discussed. Forty-eight studies using DTI to examine diffusion properties of…

  20. Evaluation of glymphatic system activity with the diffusion MR technique: diffusion tensor image analysis along the perivascular space (DTI-ALPS) in Alzheimer’s disease cases

    OpenAIRE

    Taoka, Toshiaki; Masutani, Yoshitaka; Kawai, Hisashi; Nakane, Toshiki; Matsuoka, Kiwamu; Yasuno, Fumihiko; Kishimoto, Toshifumi; Naganawa, Shinji

    2017-01-01

    Purpose: The activity of the glymphatic system is impaired in animal models of Alzheimer’s disease (AD). We evaluated the activity of the human glymphatic system in cases of AD with a diffusion-based technique called diffusion tensor image analysis along the perivascular space (DTI-ALPS). Materials and methods: Diffusion tensor images were acquired to calculate diffusivities in the x, y, and z axes of the plane of the lateral ventricle body in 31 patients. We evaluated the diffusivity along t...

  1. Assessment of axonal degeneration in Alzheimer's disease with diffusion tensor MRI

    International Nuclear Information System (INIS)

    Stahl, R.; Dietrich, O.; Reiser, M.F.; Schoenberg, S.O.; Teipel, S.; Hampel, H.

    2003-01-01

    Alzheimer disease (AD) causes cortical degeneration with subsequent degenerative changes of the white matter. The aim of this study was to investigate the extent of white matter tissue damage of patients with Alzheimer's disease in comparison with healthy subjects using diffusion tensor MRI (DTI). The value of integrated parallel imaging techniques (iPAT) for reduction of image distortion was assessed. We studied 9 patients with mild AD and 10 age and gender matched healthy controls. DTI brain scans were obtained on a 1.5 tesla system (Siemens Magnetom Sonata) using parallel imaging (iPAT) and an EPI diffusion sequence with TE/TR 71 ms/6000 ms. We used an 8-element head coil and a GRAPPA reconstruction algorithm with an acceleration factor of 2. From the tensor, the mean diffusivity (D), the fractional anisotropy (FA), and the relative anisotropy (RA) of several white matter regions were determined. FA was significantly lower (p [de

  2. Illustrative uncertainty visualization of DTI fiber pathways

    NARCIS (Netherlands)

    Brecheisen, R.; Platel, B.; Haar Romeny, B.M. Ter; Vilanova, A.

    2013-01-01

    Diffusion Tensor Imaging (DTI) and fiber tracking provide unique insight into the 3D structure of fibrous tissues in the brain. However, the output of fiber tracking contains a significant amount of uncertainty accumulated in the various steps of the processing pipeline. Existing DTI visualization

  3. Diffusion Tensor Imaging Evaluation of Neural Network Development in Patients Undergoing Therapeutic Repetitive Transcranial Magnetic Stimulation following Stroke

    Directory of Open Access Journals (Sweden)

    Naoki Yamada

    2018-01-01

    Full Text Available We aimed to investigate plastic changes in cerebral white matter structures using diffusion tensor imaging following a 15-day stroke rehabilitation program. We compared the detection of cerebral plasticity between generalized fractional anisotropy (GFA, a novel tool for investigating white matter structures, and fractional anisotropy (FA. Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS of 2400 pulses applied to the nonlesional hemisphere and 240 min intensive occupation therapy (OT daily over 15 days. Motor function was evaluated using the Fugl-Meyer assessment (FMA and Wolf Motor Function Test (WMFT. Patients underwent diffusion tensor magnetic resonance imaging (MRI on admission and discharge, from which bilateral FA and GFA values in Brodmann area (BA 4 and BA6 were calculated. Motor function improved following treatment (p<0.001. Treatment increased GFA values for both the lesioned and nonlesioned BA4 (p<0.05, p<0.001, resp.. Changes in GFA value for BA4 of the lesioned hemisphere were significantly inversely correlated with changes in WMFT scores (R2=0.363, p<0.05. Our findings indicate that the GFA may have a potentially more useful ability than FA to detect changes in white matter structures in areas of fiber intersection for any such future investigations.

  4. Identifiability analysis of rotational diffusion tensor and electronic transition moments measured in time-resolved fluorescence depolarization experiment

    International Nuclear Information System (INIS)

    Szubiakowski, Jacek P.

    2014-01-01

    The subject of this paper is studies of the deterministic identifiability of molecular parameters, such as rotational diffusion tensor components and orientation of electronic transition moments, resulting from the time-resolved fluorescence anisotropy experiment. In the most general case considered, a pair of perpendicularly polarized emissions enables the unique determination of all the rotational diffusion tensor's principal components. The influence of the tensor's symmetry and the associated degeneration of its eigenvalues on the identifiability of the electronic transitions moments is systematically investigated. The analysis reveals that independently of the rotational diffusion tensor's symmetry, the transition moments involved in photoselection and emission processes cannot be uniquely identified without a priori information about their mutual orientation or their orientation with respect to the principal axes of the tensor. Moreover, it is shown that increasing the symmetry of the rotational diffusion tensor deteriorates the degree of the transition moments identifiability. To obtain these results analytically, a novel approach to solve bilinear system of equations for Markov parameters is applied. The effect of the additional information, obtained from fluorescence measurements for different molecular mobilities, to improve the identifiability at various levels of analysis is shown. The effectiveness and reliability of the target analysis method for experimental determination of the molecular parameters is also discussed

  5. Corticospinal tract degeneration and possible pathogenesis in ALS evaluated by MR diffusion tensor imaging

    DEFF Research Database (Denmark)

    Karlsborg, Merete; Rosenbaum, Sverre; Wiegell, Mette R.

    2004-01-01

    BACKGROUND: MR diffusion tensor imaging (DTI) appears to be a powerful method to investigate the neuronal and axonal fibre distribution in the human brain. Changes in diffusion characteristics of water molecules in the white matter can be estimated as the apparent diffusion coefficient (ADC...

  6. Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children

    International Nuclear Information System (INIS)

    Sreedharan, Ruma Madhu; Menon, Amitha C.; Thomas, Sanjeev V.; James, Jija S.; Kesavadas, Chandrasekharan

    2015-01-01

    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms - visual verb generation and word pair task - were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p < 0.02) between fMRI-LI and DTI-LI. Group mean of AFV by DTI was higher on the left side (2659.89 ± 654.75 mm 3 ) as compared to the right (1824.11 ± 582.81 mm 3 ) (p < 0.01). Like fMRI, DTI also reveals language laterality in children with a high degree of correlation between the two imaging modalities. (orig.)

  7. Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children

    Energy Technology Data Exchange (ETDEWEB)

    Sreedharan, Ruma Madhu [Government Medical College Hospital, Department of Radiology, Trivandrum, Kerala (India); Menon, Amitha C.; Thomas, Sanjeev V. [Sree Chitra, Thirunal Institute for Medical Sciences and Technology, Department of Neurology, Thiruvananthapuram, Kerala (India); James, Jija S.; Kesavadas, Chandrasekharan [SCTIMST, Department of Imaging Science and Interventional Radiology, Trivandrum, Kerala (India)

    2015-03-01

    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms - visual verb generation and word pair task - were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p < 0.02) between fMRI-LI and DTI-LI. Group mean of AFV by DTI was higher on the left side (2659.89 ± 654.75 mm{sup 3}) as compared to the right (1824.11 ± 582.81 mm{sup 3}) (p < 0.01). Like fMRI, DTI also reveals language laterality in children with a high degree of correlation between the two imaging modalities. (orig.)

  8. High angular resolution diffusion imaging : processing & visualization

    NARCIS (Netherlands)

    Prckovska, V.

    2010-01-01

    Diffusion tensor imaging (DTI) is a recent magnetic resonance imaging (MRI) technique that can map the orientation architecture of neural tissues in a completely non-invasive way by measuring the directional specificity (anisotropy) of the local water diffusion. However, in areas of complex fiber

  9. 3D structure tensor analysis of light microscopy data for validating diffusion MRI.

    Science.gov (United States)

    Khan, Ahmad Raza; Cornea, Anda; Leigland, Lindsey A; Kohama, Steven G; Jespersen, Sune Nørhøj; Kroenke, Christopher D

    2015-05-01

    Diffusion magnetic resonance imaging (d-MRI) is a powerful non-invasive and non-destructive technique for characterizing brain tissue on the microscopic scale. However, the lack of validation of d-MRI by independent experimental means poses an obstacle to accurate interpretation of data acquired using this method. Recently, structure tensor analysis has been applied to light microscopy images, and this technique holds promise to be a powerful validation strategy for d-MRI. Advantages of this approach include its similarity to d-MRI in terms of averaging the effects of a large number of cellular structures, and its simplicity, which enables it to be implemented in a high-throughput manner. However, a drawback of previous implementations of this technique arises from it being restricted to 2D. As a result, structure tensor analyses have been limited to tissue sectioned in a direction orthogonal to the direction of interest. Here we describe the analytical framework for extending structure tensor analysis to 3D, and utilize the results to analyze serial image "stacks" acquired with confocal microscopy of rhesus macaque hippocampal tissue. Implementation of 3D structure tensor procedures requires removal of sources of anisotropy introduced in tissue preparation and confocal imaging. This is accomplished with image processing steps to mitigate the effects of anisotropic tissue shrinkage, and the effects of anisotropy in the point spread function (PSF). In order to address the latter confound, we describe procedures for measuring the dependence of PSF anisotropy on distance from the microscope objective within tissue. Prior to microscopy, ex vivo d-MRI measurements performed on the hippocampal tissue revealed three regions of tissue with mutually orthogonal directions of least restricted diffusion that correspond to CA1, alveus and inferior longitudinal fasciculus. We demonstrate the ability of 3D structure tensor analysis to identify structure tensor orientations that

  10. Quantification of diffusion and anisotropy in intracranial epidermoids using diffusion tensor metrics and p: q tensor decomposition.

    Science.gov (United States)

    Srinivasan, K; Thomas, B; Shah, D; Kannath, S K; Menon, G; Sandhyamani, S; Kesavadas, C; Kapilamoorthy, T R

    2016-12-01

    To quantitatively evaluate the diffusion tensor metrics p, q, L and fractional anisotropy in intracranial epidermoids in comparison with normal white matter in the splenium of the corpus callosum. This retrospective study included 20 consecutive patients referred to our institute. All patients had a magnetic resonance imaging (MRI) study on a 1.5-Tesla MR system. A spin-echo echo-planar DTI sequence with diffusion gradients along 30 non-collinear directions was performed. The eigen values (λ 1 , λ 2 , λ 3 ) were computed for each voxel and, using p: q tensor decomposition, the DTI metrics p, q and L-values and fractional anositropy (FA) were calculated. The region of interest (ROI) (6 pixels each) was placed within the lesion in all the cases and in the splenium of the corpus callosum. The mean FA in the lesion and splenium were 0.50 and 0.88 respectively, with a statistically significant difference between them (Ptensor decomposition, the mean p-value in the epidermoid was 1.55±0.24 and 1.35±0.20 in the splenium; the mean q-values in the epidermoid was 0.67±0.13 and 1.27±0.17 in the splenium; the differences were statistically significant (P=0.01 and <0.01 respectively). The significant difference between p- and q-values in epidermoids compared with the splenium of callosum was probably due to structural and orientation differences in the keratin flakes in epidermoids and white matter bundles in the callosum. However, no significant statistical difference in L-values was noted (P=0.44). DTI metrics p and q have the potential to quantify the diffusion and anisotropy in various tissues thereby gaining information about their internal architecture. The results also suggest that significant differences of DTI metrics p and q between epidermoid and the splenium of the corpus callosum are due to the difference in structural organization within them. Copyright © 2016. Published by Elsevier Masson SAS.

  11. Quantifying anisotropy and fiber orientation in human brain histological sections

    Directory of Open Access Journals (Sweden)

    Matthew D Budde

    2013-02-01

    Full Text Available Diffusion weighted imaging (DWI has provided unparalleled insight into the microscopic structure and organization of the central nervous system. Diffusion tensor imaging (DTI and other models of the diffusion MRI signal extract microstructural properties of tissues with relevance to the normal and injured brain. Despite the prevalence of such techniques and applications, accurate and large-scale validation has proven difficult, particularly in the human brain. In this report, human brain sections obtained from a digital public brain bank were employed to quantify anisotropy and fiber orientation using structure tensor analysis. The derived maps depict the intricate complexity of white matter fibers at a resolution not attainable with current DWI experiments. Moreover, the effects of multiple fiber bundles (i.e. crossing fibers and intravoxel fiber dispersion were demonstrated. Examination of the cortex and hippocampal regions validated specific features of previous in vivo and ex vivo DTI studies of the human brain. Despite the limitation to two dimensions, the resulting images provide a unique depiction of white matter organization at resolutions currently unattainable with DWI. The method of analysis may be used to validate tissue properties derived from DTI and alternative models of the diffusion signal.

  12. Diffusion tensor imaging of occult injury of optic radiation following optic neuritis in multiple sclerosis.

    Science.gov (United States)

    Chen, Jiafeng; Zhu, Lijun; Li, He; Lu, Ziwen; Chen, Xin; Fang, Shaokuan

    2016-10-01

    Multiple sclerosis (MS) is easily detected by routine magnetic resonance imaging (MRI). However, it is not possible to detect early or occult lesions in MS by routine MRI, and this may explain the inconsistency between the severity of the lesions found by MRI and the degree of clinical disability of patients with MS. The present study included 10 patients with relapsing-remitting MS and 10 healthy volunteers. Each patient underwent routine 3.0 T MRI, diffusion tensor imaging (DTI), and diffusion tensor tractography (DTT). Optic nerve and optic radiation were analyzed by DTI and DTT. The fractional anisotropy (FA), mean diffusivity (MD), λ // , and λ ┴ values were measured. In the 10 patients with MS, 7 optic nerves were affected, and 13 optic nerves were not affected. Cranial MRI showed that optic nerve thickening and hyperintensity occurred in 2 patients with MS. In the directionally encoded color maps, a hypointensive green signal in the optic nerve was observed in 3 patients with MS. The FA values were significantly lower and the MD, λ // , and λ ┴ values were significantly higher in the affected and unaffected optic nerves and optic radiations in patients with MS in comparison with controls (P0.05). Diffusion tensor imaging is sensitive in the detection of occult injury of the optic nerve and optic radiation following optic neuritis. Diffusion tensor imaging may be a useful tool for the early diagnosis, treatment and management of MS.

  13. Total magnitude of diffusion tensor imaging as an effective tool for the differentiation of glioma

    Energy Technology Data Exchange (ETDEWEB)

    Smitha, Karavallil A., E-mail: mithamahesh@gmail.com [Department of Imaging Sciences and Interventional Radiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram (India); Gupta, Arun kumar, E-mail: gupta209@gmail.com [Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neuro Sciences, Bangalore (India); Jayasree, Ramapurath S., E-mail: jayashreemenon@gmail.com [Biophotonics and Imaging Laboratory, Biomedical Technology Wing, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram (India)

    2013-05-15

    Objectives: The study aims to evaluate the difference in diffusion properties between high grade glioma and low grade glioma by measuring the total magnitude of diffusion tensor (L), and its isotropic (p) and anisotropic (q) components. Methods: The diffusion tensor parameters p, q, L and FA from the tumor area, adjacent area to the tumor and corresponding contra lateral normal area of 30 high grade glioma and 49 low grade glioma were calculated. Chi square analysis was done to find the changes in age and sex. One Way ANOVA was performed to compare the mean and ROC curve analysis to confirm the discriminative sensitivity. Results: Major variation in the mean values of p, L and FA was observed in different brain areas considered. Variation in the p and L values between low grade and high grade glioma were statistically significant (p < 0.001) and their ROC curve analysis yielded 93.9% and 91.8% sensitivity and 53.3% specificity respectively. Conclusion: Measurement of the isotropic component p and the total value of diffusion tensor L can be effectively correlated with different grades of glioma and can be used to study the diffusion properties of tumor affected brain.

  14. The Disruption of Geniculocalcarine Tract in Occipital Neoplasm: A Diffusion Tensor Imaging Study

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2016-01-01

    Full Text Available Aim. Investigate the disruption of geniculocalcarine tract (GCT in different occipital neoplasm by diffusion tensor imaging (DTI. Methods. Thirty-two subjects (44.1 ± 3.6 years who had single occipital neoplasm (9 gliomas, 6 meningiomas, and 17 metastatic tumors with ipsilateral GCT involved and thirty healthy subjects (39.2 ± 3.3 years underwent conventional sequences scanning and diffusion tensor imaging by a 1.5T MR scanner. The diffusion-sensitive gradient direction is 13. Compare the fractional anisotropy (FA and mean diffusivity (MD values of healthy GCT with the corresponding values of GCT in peritumoral edema area. Perform diffusion tensor tractography (DTT on GCT by the line propagation technique in all subjects. Results. The FA values of GCT in peritumoral edema area decreased (P=0.001 while the MD values increased (P=0.002 when compared with healthy subjects. There was no difference in the FA values across tumor types (P=0.114 while the MD values of GCT in the metastatic tumor group were higher than the other groups (P=0.001. GCTs were infiltrated in all the 9 gliomas cases, with displacement in 2 cases and disruption in 7 cases. GCTs were displaced in 6 meningiomas cases. GCTs were displaced in all the 7 metastatic cases, with disruption in 7 cases. Conclusions. DTI represents valid markers for evaluating GCT’s disruption in occipital neoplasm. The disruption of GCT varies according to the properties of neoplasm.

  15. Visualization of transverse diffusion paths across fiber cells of the ocular lens by small animal MRI

    International Nuclear Information System (INIS)

    Vaghefi, Ehsan; Hunter, Peter J; Jacobs, Marc D; Pontre, Beau; Donaldson, Paul J

    2009-01-01

    The sense of vision requires that light penetrate through the ocular lens. Experiments, performed and published by many research groups, have suggested that the lens, which has no blood vessels, relies on internally directed ion and water fluxes for its circulation, survival and transparency. We investigated the internal diffusive pathways of the lens in order to better understand the constraints that may be operating on directional lens fluxes. Small animal magnetic resonance imaging, including T2-weighted and diffusion tensor imaging, was used to measure tissue properties and diffusivity throughout cultured bovine lenses. A range of concentric regions of signal intensity was distinguished inside the lens, by both T2-weighted signal and mean diffusivity. Diffusivity mapping of the lens revealed novel anisotropic polar and equatorial zones of pronounced diffusivity directed transverse to the fiber cells. In contrast, an inner zone including the lens nucleus showed isotropic and weak diffusivity. Our results lend support to models of internally directed lens micro-circulation, by placing non-structural diffusive constraints on global patterns of fluid circulation

  16. Cardiac fiber orientation in goat measured with Diffusion Tensor Imaging

    NARCIS (Netherlands)

    Ossevoort, L.; Bovendeerd, P.H.M.; Nicolaij, K.; Arts, M.G.J.

    2000-01-01

    We therefore hypothesize that fiber reorientation could be a local adaptive mechanism by which the strain distribution across the cardiac wall is homogenized. To test this hypothesis we measured fiber orientation in normal goat hearts and in goat hearts in which the mechanical load was locally

  17. Direct comparison of in vivo versus postmortem second-order motion-compensated cardiac diffusion tensor imaging.

    Science.gov (United States)

    Stoeck, Christian T; von Deuster, Constantin; Fleischmann, Thea; Lipiski, Miriam; Cesarovic, Nikola; Kozerke, Sebastian

    2018-04-01

    To directly compare in vivo versus postmortem second-order motion-compensated spin-echo diffusion tensor imaging of the porcine heart. Second-order motion-compensated spin-echo cardiac diffusion tensor imaging was performed during systolic contraction in vivo and repeated upon cardiac arrest by bariumchloride without repositioning of the study animal or replaning of imaging slices. In vivo and postmortem reproducibility was assessed by repeat measurements. Comparison of helix, transverse, and sheet (E2A) angulation as well as mean diffusivity and fractional anisotropy was performed. Intraclass correlation coefficients for repeated measurements (postmortem/in vivo) were 0.95/0.96 for helix, 0.70/0.66 for transverse, and 0.79/0.72 for E2A angulation; 0.83/0.72 for mean diffusivity; and 0.78/0.76 for fractional anisotropy. The corresponding 95% levels of agreement across the left ventricle were: helix 14 to 18°/12 to 15°, transverse 9 to 10°/10 to 11°, E2A 15 to 20°/16 to 18°. The 95% levels of agreement across the left ventricle for the comparison of postmortem versus in vivo were 20 to 22° for helix, 13 to 19° for transverse, and 24 to 31° for E2A angulation. Parameters derived from in vivo second-order motion-compensated spin-echo diffusion tensor imaging agreed well with postmortem imaging, indicating sufficient suppression of motion-induced signal distortions of in vivo cardiac diffusion tensor imaging. Magn Reson Med 79:2265-2276, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  18. Susceptibility Tensor Imaging (STI) of the Brain

    Science.gov (United States)

    Li, Wei; Liu, Chunlei; Duong, Timothy Q.; van Zijl, Peter C.M.; Li, Xu

    2016-01-01

    Susceptibility tensor imaging (STI) is a recently developed MRI technique that allows quantitative determination of orientation-independent magnetic susceptibility parameters from the dependence of gradient echo signal phase on the orientation of biological tissues with respect to the main magnetic field. By modeling the magnetic susceptibility of each voxel as a symmetric rank-2 tensor, individual magnetic susceptibility tensor elements as well as the mean magnetic susceptibility (MMS) and magnetic susceptibility anisotropy (MSA) can be determined for brain tissues that would still show orientation dependence after conventional scalar-based quantitative susceptibility mapping (QSM) to remove such dependence. Similar to diffusion tensor imaging (DTI), STI allows mapping of brain white matter fiber orientations and reconstruction of 3D white matter pathways using the principal eigenvectors of the susceptibility tensor. In contrast to diffusion anisotropy, the main determinant factor of susceptibility anisotropy in brain white matter is myelin. Another unique feature of susceptibility anisotropy of white matter is its sensitivity to gadolinium-based contrast agents. Mechanistically, MRI-observed susceptibility anisotropy is mainly attributed to the highly ordered lipid molecules in myelin sheath. STI provides a consistent interpretation of the dependence of phase and susceptibility on orientation at multiple scales. This article reviews the key experimental findings and physical theories that led to the development of STI, its practical implementations, and its applications for brain research. PMID:27120169

  19. Spatial Mapping of Structural and Connectional Imaging Data for the Developing Human Brain with Diffusion Tensor Imaging

    Science.gov (United States)

    Ouyang, Austin; Jeon, Tina; Sunkin, Susan M.; Pletikos, Mihovil; Sedmak, Goran; Sestan, Nenad; Lein, Ed S.; Huang, Hao

    2014-01-01

    During human brain development from fetal stage to adulthood, the white matter (WM) tracts undergo dramatic changes. Diffusion tensor imaging (DTI), a widely used magnetic resonance imaging (MRI) modality, offers insight into the dynamic changes of WM fibers as these fibers can be noninvasively traced and three-dimensionally (3D) reconstructed with DTI tractography. The DTI and conventional T1 weighted MRI images also provide sufficient cortical anatomical details for mapping the cortical regions of interests (ROIs). In this paper, we described basic concepts and methods of DTI techniques that can be used to trace major WM tracts noninvasively from fetal brain of 14 postconceptional weeks (pcw) to adult brain. We applied these techniques to acquire DTI data and trace, reconstruct and visualize major WM tracts during development. After categorizing major WM fiber bundles into five unique functional tract groups, namely limbic, brain stem, projection, commissural and association tracts, we revealed formation and maturation of these 3D reconstructed WM tracts of the developing human brain. The structural and connectional imaging data offered by DTI provides the anatomical backbone of transcriptional atlas of the developing human brain. PMID:25448302

  20. Spatial mapping of structural and connectional imaging data for the developing human brain with diffusion tensor imaging.

    Science.gov (United States)

    Ouyang, Austin; Jeon, Tina; Sunkin, Susan M; Pletikos, Mihovil; Sedmak, Goran; Sestan, Nenad; Lein, Ed S; Huang, Hao

    2015-02-01

    During human brain development from fetal stage to adulthood, the white matter (WM) tracts undergo dramatic changes. Diffusion tensor imaging (DTI), a widely used magnetic resonance imaging (MRI) modality, offers insight into the dynamic changes of WM fibers as these fibers can be noninvasively traced and three-dimensionally (3D) reconstructed with DTI tractography. The DTI and conventional T1 weighted MRI images also provide sufficient cortical anatomical details for mapping the cortical regions of interests (ROIs). In this paper, we described basic concepts and methods of DTI techniques that can be used to trace major WM tracts noninvasively from fetal brain of 14 postconceptional weeks (pcw) to adult brain. We applied these techniques to acquire DTI data and trace, reconstruct and visualize major WM tracts during development. After categorizing major WM fiber bundles into five unique functional tract groups, namely limbic, brain stem, projection, commissural and association tracts, we revealed formation and maturation of these 3D reconstructed WM tracts of the developing human brain. The structural and connectional imaging data offered by DTI provides the anatomical backbone of transcriptional atlas of the developing human brain. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Diffusion abnormalities of the uncinate fasciculus in Alzheimer's disease: diffusion tensor tract-specific analysis using a new method to measure the core of the tract

    International Nuclear Information System (INIS)

    Yasmin, Hasina; Nakata, Yasuhiro; Abe, Osamu; Masutani, Yoshitaka; Ohtomo, Kuni; Aoki, Shigeki; Sato, Noriko; Nemoto, Kiyotaka; Arima, Kunimasa; Furuta, Nobuo; Uno, Masatake; Hirai, Shigeo

    2008-01-01

    Our aim was to determine diffusion abnormalities in the uncinate fasciculus (UF) in Alzheimer's disease (AD) by diffusion tensor tractography (DTT) using a new method for measuring the core of the tract. We studied 19 patients with AD and 19 age-matched control subjects who underwent MRI using diffusion tensor imaging (DTI). DTT of the UF was generated. The mean diffusivity (MD) and fractional anisotropy (FA) of the core of the tract were measured after voxelized tract shape processing. Student's t-test was used to compare results between patients with AD and controls. Intraobserver correlation tests were also performed. FA was significantly lower (P 0.93 for measured FA and r > 0.92 for measured MD. Our results suggest that FA reflects progression of AD-related histopathological changes in the UF of the white matter and may represent a useful biological index in monitoring AD. Diffusion tensor tract-specific analysis with voxelized tract shape processing to measure the core of the tract may be a sensitive tool for evaluation of diffusion abnormalities of white matter tracts in AD. (orig.)

  2. Fast and Analytical EAP Approximation from a 4th-Order Tensor.

    Science.gov (United States)

    Ghosh, Aurobrata; Deriche, Rachid

    2012-01-01

    Generalized diffusion tensor imaging (GDTI) was developed to model complex apparent diffusivity coefficient (ADC) using higher-order tensors (HOTs) and to overcome the inherent single-peak shortcoming of DTI. However, the geometry of a complex ADC profile does not correspond to the underlying structure of fibers. This tissue geometry can be inferred from the shape of the ensemble average propagator (EAP). Though interesting methods for estimating a positive ADC using 4th-order diffusion tensors were developed, GDTI in general was overtaken by other approaches, for example, the orientation distribution function (ODF), since it is considerably difficult to recuperate the EAP from a HOT model of the ADC in GDTI. In this paper, we present a novel closed-form approximation of the EAP using Hermite polynomials from a modified HOT model of the original GDTI-ADC. Since the solution is analytical, it is fast, differentiable, and the approximation converges well to the true EAP. This method also makes the effort of computing a positive ADC worthwhile, since now both the ADC and the EAP can be used and have closed forms. We demonstrate our approach with 4th-order tensors on synthetic data and in vivo human data.

  3. Peritumoral edema of meningiomas and metastatic brain tumors: differences in diffusion characteristics evaluated with diffusion-tensor MR imaging

    International Nuclear Information System (INIS)

    Toh, Cheng-Hong; Wong, Alex M.-C; Wong, Ho-Fai; Wan, Yung-Liang; Wei, Kuo-Chen; Ng, Shu-Hang

    2007-01-01

    We prospectively compared the fractional anisotropy (FA) and mean diffusivity (MD) of the peritumoral edema of meningiomas and metastatic brain tumors with diffusion-tensor magnetic resonance (MR) imaging. The study protocol was approved by the local ethics committee, and written informed consent was obtained. Preoperative diffusion-tensor MR imaging was performed in 15 patients with meningiomas and 11 patients with metastatic brain tumors. Regions of interest (ROI) were placed in the peritumoral edema and normal-appearing white matter (NAWM) of the contralateral hemisphere to measure the FA and MD. The FA and MD ratios were calculated for each ROI in relation to the NAWM of the contralateral hemisphere. Changes in peritumoral MD and FA, in terms of primary values and ratios, were compared using a two-sample t-test; P -3 mm 2 /s) of the peritumoral edema for metastases and meningiomas, respectively, were 0.902 ± 0.057 and 0.820 ± 0.094, the mean MD ratios were 220.3 ± 22.6 and 193.1 ± 23.4, the mean FA values were 0.146 ± 0.026 and 0.199 ± 0.052, and the mean FA ratios were 32.3 ± 5.9 and 46.0 ± 12.1. All the values were significantly different between metastases and meningiomas (MD values P 0.016, MD ratios P = 0.006, FA values P = 0.005, FA ratios P = 0.002). The peritumoral edema of metastatic brain tumors and meningiomas show different MD and FA on diffusion-tensor MR imaging. (orig.)

  4. Peritumoral edema of meningiomas and metastatic brain tumors: differences in diffusion characteristics evaluated with diffusion-tensor MR imaging

    Energy Technology Data Exchange (ETDEWEB)

    Toh, Cheng-Hong; Wong, Alex M.-C; Wong, Ho-Fai; Wan, Yung-Liang [Chang Gung Memorial Hospital, Department of Medical Imaging and Intervention, Tao-Yuan (China); Chang Gung University, School of Medicine and Medical Technology, Tao-Yuan (China); Wei, Kuo-Chen [Chang Gung Memorial Hospital, Department of Neurosurgery, Tao-Yuan (China); Chang Gung University, School of Medicine and Medical Technology, Tao-Yuan (China); Ng, Shu-Hang [Chang Gung Memorial Hospital, Department of Medical Imaging and Intervention, Tao-Yuan (China); Chang Gung University, School of Medicine and Medical Technology, Tao-Yuan (China); Chang Gung Memorial Hospital, Molecular Image Center, Tao-Yuan (China)

    2007-06-15

    We prospectively compared the fractional anisotropy (FA) and mean diffusivity (MD) of the peritumoral edema of meningiomas and metastatic brain tumors with diffusion-tensor magnetic resonance (MR) imaging. The study protocol was approved by the local ethics committee, and written informed consent was obtained. Preoperative diffusion-tensor MR imaging was performed in 15 patients with meningiomas and 11 patients with metastatic brain tumors. Regions of interest (ROI) were placed in the peritumoral edema and normal-appearing white matter (NAWM) of the contralateral hemisphere to measure the FA and MD. The FA and MD ratios were calculated for each ROI in relation to the NAWM of the contralateral hemisphere. Changes in peritumoral MD and FA, in terms of primary values and ratios, were compared using a two-sample t-test; P < 0.05 was taken as indicating statistical significance. The mean MD values (x 10{sup -3} mm{sup 2}/s) of the peritumoral edema for metastases and meningiomas, respectively, were 0.902 {+-} 0.057 and 0.820 {+-} 0.094, the mean MD ratios were 220.3 {+-} 22.6 and 193.1 {+-} 23.4, the mean FA values were 0.146 {+-} 0.026 and 0.199 {+-} 0.052, and the mean FA ratios were 32.3 {+-} 5.9 and 46.0 {+-} 12.1. All the values were significantly different between metastases and meningiomas (MD values P = 0.016, MD ratios P = 0.006, FA values P = 0.005, FA ratios P = 0.002). The peritumoral edema of metastatic brain tumors and meningiomas show different MD and FA on diffusion-tensor MR imaging. (orig.)

  5. In-utero three dimension high resolution fetal brain diffusion tensor imaging.

    Science.gov (United States)

    Jiang, Shuzhou; Xue, Hui; Counsell, Serena; Anjari, Mustafa; Allsop, Joanna; Rutherford, Mary; Rueckert, Daniel; Hajnal, Joseph V

    2007-01-01

    We present a methodology to achieve 3D high resolution in-utero fetal brain DTI that shows excellent ADC as well as promising FA maps. After continuous DTI scanning to acquire a repeated series of parallel slices with 15 diffusion directions, image registration is used to realign the images to correct for fetal motion. Once aligned, the diffusion images are treated as irregularly sampled data where each voxel is associated with an appropriately rotated diffusion direction, and used to estimate the diffusion tensor on a regular grid. The method has been tested successful on eight fetuses and has been validated on adults imaged at 1.5T.

  6. Diffusion-weighted imaging and diffusion tensor imaging of asymptomatic lumbar disc herniation.

    Science.gov (United States)

    Sakai, Toshinori; Miyagi, Ryo; Yamabe, Eiko; Fujinaga, Yasunari; N Bhatia, Nitin; Yoshioka, Hiroshi

    2014-01-01

    Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) were performed on a healthy 31-year-old man with asymptomatic lumbar disc herniation. Although the left S1 nerve root was obviously entrapped by a herniated mass, neither DWI nor DTI showed any significant findings for the nerve root. Decreased apparent diffusion coefficient (ADC) values and increased fractional anisotropy (FA) values were found. These results are contrary to those in previously published studies of symptomatic patients, in which a combination of increased ADC and decreased FA seem to have a relationship with nerve injury and subsequent symptoms, such as leg pain or palsy. Our results seen in an asymptomatic subject suggest that the compressed nerve with no injury, such as edema, demyelination, or persistent axonal injury, may be indicated by a combination of decreased ADC and increased FA. ADC and FA could therefore be potential tools to elucidate the pathomechanism of radiculopathy.

  7. Comparative assessment of therapeutic response to physiotherapy with or without botulinum toxin injection using diffusion tensor tractography and clinical scores in term diplegic cerebral palsy children.

    Science.gov (United States)

    Chaturvedi, Saurabh K; Rai, Yogita; Chourasia, Ankita; Goel, Puneet; Paliwal, Vimal K; Garg, Ravindra K; Rathore, Ram Kishore S; Pandey, Chandra M; Gupta, Rakesh K

    2013-08-01

    The present study was to compare the effects of combined therapy [botulinum (BTX) plus physiotherapy] with physiotherapy alone using diffusion tensor imaging (DTI) derived fractional anisotropy (FA) values of motor and sensory fiber bundles and clinical grade of the disability to see the value of BTX in term children with spastic diplegic cerebral palsy (CP). Clinically diagnosed 36 children participated in the study. All these children were born at term, and had no history of seizures. The study was randomly categorized into two groups: group I (n=18) - physiotherapy alone and group II (n=18) - physiotherapy plus BTX injection. Quantitative diffusion tensor tractography on all these children was performed on motor and sensory fiber bundles on baseline as well as after 6months of therapy. Motor function and clinical grades were also measured by gross motor function measures (GMFM) scale on both occasions. We observed significant change in FA value in motor and sensory fiber bundle as well as in GMFM scores at 6months compared to baseline study in both the groups. However, delta change and relative delta change in FA values of sensory and motor fiber bundle as well as GMFM score between group I and group II was statistically insignificant. We conclude that addition of BTX to physiotherapy regimen does not influence the outcome at 6months with similar insult in children with term diplegic spastic CP. This information may influence management of diplegic CP especially in developing countries, where BTX is beyond the reach of these children. Copyright © 2012 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

  8. Diffusion tensor imaging depicting damage to the arcuate fasciculus in patients with conduction aphasia: a study of the Wernicke-Geschwind model.

    Science.gov (United States)

    Zhang, Yumei; Wang, Chunxue; Zhao, Xingquan; Chen, Hongyan; Han, Zaizhu; Wang, Yongjun

    2010-09-01

    In contrast with disorders of comprehension and spontaneous expression, conduction aphasia is characterized by poor repetition, which is a hallmark of the syndrome. There are many theories on the repetition impairment of conduction aphasia. The disconnection theory suggests that a damaged in the arcuate fasciculus, which connects Broca's and Wernicke's area, is the cause of conduction aphasia. In this study, we examined the disconnection theory. We enrolled ten individuals with conduction aphasia and ten volunteers, and analysed their arcuate fasciculus using diffusion tensor imaging (DTI) and obtained fractional anisotropy (FA) values. Then, the results of the left hemisphere were compared with those of the right hemisphere, and the results of the conduction aphasia cases were compared with those of the volunteers. There were significant differences in the FA values between the left and right hemispheres of volunteers and conduction cases. In volunteers, there was an increase in fiber in the left hemisphere compared with the right hemisphere, whereas there was an increase in fiber in the right hemisphere compared with the left hemisphere in conduction aphasia patients. The results of diffusion tensor tractography suggested that the configuration of the arcuate fasciculus was different between conduction aphasia patients and volunteers, suggesting that there was damage to the arcuate fasciculus of conduction aphasia cases. The damage seen in the arcuate fasciculus of conduction aphasia cases in this study supports the Wernicke-Geschwind disconnection theory. A disconnection between Broca's area and Wernicke's area is likely to be one mechanism of conduction aphasia repetition impairment.

  9. Segmentation of corpus callosum using diffusion tensor imaging: validation in patients with glioblastoma

    International Nuclear Information System (INIS)

    Nazem-Zadeh, Mohammad-Reza; Saksena, Sona; Babajani-Fermi, Abbas; Jiang, Quan; Soltanian-Zadeh, Hamid; Rosenblum, Mark; Mikkelsen, Tom; Jain, Rajan

    2012-01-01

    This paper presents a three-dimensional (3D) method for segmenting corpus callosum in normal subjects and brain cancer patients with glioblastoma. Nineteen patients with histologically confirmed treatment naïve glioblastoma and eleven normal control subjects underwent DTI on a 3T scanner. Based on the information inherent in diffusion tensors, a similarity measure was proposed and used in the proposed algorithm. In this algorithm, diffusion pattern of corpus callosum was used as prior information. Subsequently, corpus callosum was automatically divided into Witelson subdivisions. We simulated the potential rotation of corpus callosum under tumor pressure and studied the reproducibility of the proposed segmentation method in such cases. Dice coefficients, estimated to compare automatic and manual segmentation results for Witelson subdivisions, ranged from 94% to 98% for control subjects and from 81% to 95% for tumor patients, illustrating closeness of automatic and manual segmentations. Studying the effect of corpus callosum rotation by different Euler angles showed that although segmentation results were more sensitive to azimuth and elevation than skew, rotations caused by brain tumors do not have major effects on the segmentation results. The proposed method and similarity measure segment corpus callosum by propagating a hyper-surface inside the structure (resulting in high sensitivity), without penetrating into neighboring fiber bundles (resulting in high specificity)

  10. White matter and schizophrenia: A meta-analysis of voxel-based morphometry and diffusion tensor imaging studies.

    Science.gov (United States)

    Vitolo, Enrico; Tatu, Mona Karina; Pignolo, Claudia; Cauda, Franco; Costa, Tommaso; Ando', Agata; Zennaro, Alessandro

    2017-12-30

    Voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) are the most implemented methodologies to detect alterations of both gray and white matter (WM). However, the role of WM in mental disorders is still not well defined. We aimed at clarifying the role of WM disruption in schizophrenia and at identifying the most frequently involved brain networks. A systematic literature search was conducted to identify VBM and DTI studies focusing on WM alterations in patients with schizophrenia compared to control subjects. We selected studies reporting the coordinates of WM reductions and we performed the anatomical likelihood estimation (ALE). Moreover, we labeled the WM bundles with an anatomical atlas and compared VBM and DTI ALE-scores of each significant WM tract. A total of 59 studies were eligible for the meta-analysis. WM alterations were reported in 31 and 34 foci with VBM and DTI methods, respectively. The most occurred WM bundles in both VBM and DTI studies and largely involved in schizophrenia were long projection fibers, callosal and commissural fibers, part of motor descending fibers, and fronto-temporal-limbic pathways. The meta-analysis showed a widespread WM disruption in schizophrenia involving specific cerebral circuits instead of well-defined regions. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. A continuous tensor field approximation of discrete DT-MRI data for extracting microstructural and architectural features of tissue.

    Science.gov (United States)

    Pajevic, Sinisa; Aldroubi, Akram; Basser, Peter J

    2002-01-01

    The effective diffusion tensor of water, D, measured by diffusion tensor MRI (DT-MRI), is inherently a discrete, noisy, voxel-averaged sample of an underlying macroscopic effective diffusion tensor field, D(x). Within fibrous tissues this field is presumed to be continuous and smooth at a gross anatomical length scale. Here a new, general mathematical framework is proposed that uses measured DT-MRI data to produce a continuous approximation to D(x). One essential finding is that the continuous tensor field representation can be constructed by repeatedly performing one-dimensional B-spline transforms of the DT-MRI data. The fidelity and noise-immunity of this approximation are tested using a set of synthetically generated tensor fields to which background noise is added via Monte Carlo methods. Generally, these tensor field templates are reproduced faithfully except at boundaries where diffusion properties change discontinuously or where the tensor field is not microscopically homogeneous. Away from such regions, the tensor field approximation does not introduce bias in useful DT-MRI parameters, such as Trace(D(x)). It also facilitates the calculation of several new parameters, particularly differential quantities obtained from the tensor of spatial gradients of D(x). As an example, we show that they can identify tissue boundaries across which diffusion properties change rapidly using in vivo human brain data. One important application of this methodology is to improve the reliability and robustness of DT-MRI fiber tractography.

  12. Diffusion tensor imaging of the brainstem in children with achondroplasia.

    Science.gov (United States)

    Bosemani, Thangamadhan; Orman, Gunes; Carson, Kathryn A; Meoded, Avner; Huisman, Thierry A G M; Poretti, Andrea

    2014-11-01

    The aims of this study were to compare, using diffusion tensor imaging (DTI) of the brainstem, microstructural integrity of the white matter in children with achondroplasia and age-matched participants and to correlate the severity of craniocervical junction (CCJ) narrowing and neurological findings with DTI scalars in children with achondroplasia. This study also aimed to assess the potential role of fibroblast growth factor receptor type 3 on white matter microstructure. Diffusion tensor imaging was performed using a 1.5T magnetic resonance scanner and balanced pairs of diffusion gradients along 20 non-collinear directions. Measurements were obtained from regions of interest, sampled in each pontine corticospinal tract (CST), medial lemniscus, and middle cerebellar peduncle, as well as in the lower brainstem and centrum semiovale, for fractional anisotropy and for mean, axial, and radial diffusivity. In addition, a severity score for achondroplasia was assessed by measuring CCJ narrowing. Eight patients with achondroplasia (seven males, one female; mean age 5y 6mo, range 1y 1mo-15y 1mo) and eight age- and sex-matched comparison participants (mean age 5y 2mo, range 1y 1mo-14y 11mo) were included in this study. Fractional anisotropy was lower and mean diffusivity and radial diffusivity were higher in the lower brainstem of patients with achondroplasia than in age-matched comparison participants. The CST and middle cerebellar peduncle of the participants showed increases in mean, axial, and radial diffusivity. Fractional anisotropy in the lower brainstem was negatively correlated with the degree of CCJ narrowing. No differences in the DTI metrics of the centrum semiovale were observed between the two groups. The reduction in fractional anisotropy and increase in diffusivities in the lower brainstem of participants with achondroplasia may reflect secondary encephalomalacic degeneration and cavitation of the affected white matter tracts as shown by histology. In

  13. Impact of Gradient Number and Voxel Size on Diffusion Tensor Imaging Tractography for Resective Brain Surgery.

    Science.gov (United States)

    Hoefnagels, Friso W A; de Witt Hamer, Philip C; Pouwels, Petra J W; Barkhof, Frederik; Vandertop, W Peter

    2017-09-01

    To explore quantitatively and qualitatively how the number of gradient directions (NGD) and spatial resolution (SR) affect diffusion tensor imaging (DTI) tractography in patients planned for brain tumor surgery, using routine clinical magnetic resonance imaging protocols. Of 67 patients with intracerebral lesions who had 2 different DTI scans, 3 DTI series were reconstructed to compare the effects of NGD and SR. Tractographies for 4 clinically relevant tracts (corticospinal tract, superior longitudinal fasciculus, optic radiation, and inferior fronto-occipital fasciculus) were constructed with a probabilistic tracking algorithm and automated region of interest placement and compared for 3 quantitative measurements: tract volume, median fiber density, and mean fractional anisotropy, using linear mixed-effects models. The mean tractography volume and intersubject reliability were visually compared across scanning protocols, to assess the clinical relevance of the quantitative differences. Both NGD and SR significantly influenced tract volume, median fiber density, and mean fractional anisotropy, but not to the same extent. In particular, higher NGD increased tract volume and median fiber density. More importantly, these effects further increased when tracts were affected by disease. The effects were tract specific, but not dependent on threshold. The superior longitudinal fasciculus and inferior fronto-occipital fasciculus showed the most significant differences. Qualitative assessment showed larger tract volumes given a fixed confidence level, and better intersubject reliability for the higher NGD protocol. SR in the range we considered seemed less relevant than NGD. This study indicates that, under time constraints of clinical imaging, a higher number of diffusion gradients is more important than spatial resolution for superior DTI probabilistic tractography in patients undergoing brain tumor surgery. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Preliminary study of the optic radiation in healthy adults by MR diffusion tensor imaging

    International Nuclear Information System (INIS)

    Sun Jing; Guo Jing; Xu Han; Jiang Zhen; Xu Xiaoqiu; Shen Junkang; Liu Tao; Gong Zhigang

    2009-01-01

    Objective: To investigate the distribution of optic radiation fibers and the variation of Meyer loop in healthy adults. Methods: Diffusion tensor magnetic resonance images were obtained from 25 healthy volunteers using a 1.5 T MR scanner and postprocessed using the DTI Studio software. Multiple ROIs were used for fiber reconstruction. The distance between the anterior limit of Meyer loop and the temporal tip(MT) and the fraction of anisotropy (FA) at one side were compared with those at the contralateral side by paired t test. Results: Forty-nine optic radiation fibers were successfully reconstructed in 25 volunteers. The value of MT was (43.2±7.7) mm(ranged from 30.6 to 59.7 mm), and coefficient of variation was 18%. The values of MT and FA of optic radiation in the left side were (43.5±8.1) mm, (0.53±0.10) respectively, and those counterparts in the right side were (43.2±7.5) mm and (0.53± 0.07) respectively. There were no significance difference of MT or FA between the two sides (t=0.12, 0.00; P=0.91 and 1.00 respectively). Conclusions: The range of interindividual variation for MT was rather large in healthy volunteers. The preoperative measurement of the MT appears be helpful to predict the risk of the incidence of visual defect and to decrease the incidence of the complication. (authors)

  15. Diffusion Tensor Imaging of Heterotopia: Changes of Fractional Anisotropy during Radial Migration of Neurons

    Science.gov (United States)

    Kim, Jinna

    2010-01-01

    Purpose Diffusion tensor imaging provides better understanding of pathophysiology of congenital anomalies, involving central nervous system. This study was aimed to specify the pathogenetic mechanism of heterotopia, proved by diffusion tensor imaging, and establish new findings of heterotopia on fractional anisotropy maps. Materials and Methods Diffusion-weighted imaging data from 11 patients (M : F = 7 : 4, aged from 1 to 22 years, mean = 12.3 years) who visited the epilepsy clinic and received a routine seizure protocol MRI exam were retrospectively analyzed. Fractional anisotropy (FA) maps were generated from diffusion tensor imaging of 11 patients with heterotopia. Regions of interests (ROI) were placed in cerebral cortex, heterotopic gray matter and deep gray matter, including putamen. ANOVA analysis was performed for comparison of different gray matter tissues. Results Heterotopic gray matter showed signal intensities similar to normal gray matter on T1 and T2 weighted MRI. The measured FA of heterotopic gray matter was higher than that of cortical gray matter (0.236 ± 0.011 vs. 0.169 ± 0.015, p < 0.01, one way ANOVA), and slightly lower than that of deep gray matter (0.236 ± 0.011 vs. 0.259 ± 0.016, p < 0.01). Conclusion Increased FA of heterotopic gray matter suggests arrested neuron during radial migration and provides better understanding of neurodevelopment. PMID:20499428

  16. In vivo 3D neuroanatomical evaluation of periprostatic nerve plexus with 3T-MR Diffusion Tensor Imaging

    International Nuclear Information System (INIS)

    Panebianco, Valeria; Barchetti, Flavio; Sciarra, Alessandro; Marcantonio, Andrea; Zini, Chiara; Salciccia, Stefano; Collettini, Federico; Gentile, Vincenzo; Hamm, Bernard; Catalano, Carlo

    2013-01-01

    Objectives: To evaluate if Diffusion Tensor Imaging technique (DTI) can improve the visualization of periprostatic nerve fibers describing the location and distribution of entire neurovascular plexus around the prostate in patients who are candidates for prostatectomy. Materials and methods: Magnetic Resonance Imaging (MRI), including a 2D T2-weighted FSE sequence in 3 planes, 3D T2-weighted and DTI using 16 gradient directions and b = 0 and 1000, was performed on 36 patients. Three out of 36 patients were excluded from the analysis due to poor image quality (blurring N = 2, artifact N = 1). The study was approved by local ethics committee and all patients gave an informed consent. Images were evaluated by two radiologists with different experience in MRI. DTI images were analyzed qualitatively using dedicated software. Also 2D and 3D T2 images were independently considered. Results: 3D-DTI allowed description of the entire plexus of the periprostatic nerve fibers in all directions, while 2D and 3D T2 morphological sequences depicted part of the fibers, in a plane by plane analysis of fiber courses. DTI demonstrated in all patients the dispersion of nerve fibers around the prostate on both sides including the significant percentage present in the anterior and anterolateral sectors. Conclusions: DTI offers optimal representation of the widely distributed periprostatic plexus. If validated, it may help guide nerve-sparing radical prostatectomy

  17. An improved Bayesian tensor regularization and sampling algorithm to track neuronal fiber pathways in the language circuit.

    Science.gov (United States)

    Mishra, Arabinda; Anderson, Adam W; Wu, Xi; Gore, John C; Ding, Zhaohua

    2010-08-01

    The purpose of this work is to design a neuronal fiber tracking algorithm, which will be more suitable for reconstruction of fibers associated with functionally important regions in the human brain. The functional activations in the brain normally occur in the gray matter regions. Hence the fibers bordering these regions are weakly myelinated, resulting in poor performance of conventional tractography methods to trace the fiber links between them. A lower fractional anisotropy in this region makes it even difficult to track the fibers in the presence of noise. In this work, the authors focused on a stochastic approach to reconstruct these fiber pathways based on a Bayesian regularization framework. To estimate the true fiber direction (propagation vector), the a priori and conditional probability density functions are calculated in advance and are modeled as multivariate normal. The variance of the estimated tensor element vector is associated with the uncertainty due to noise and partial volume averaging (PVA). An adaptive and multiple sampling of the estimated tensor element vector, which is a function of the pre-estimated variance, overcomes the effect of noise and PVA in this work. The algorithm has been rigorously tested using a variety of synthetic data sets. The quantitative comparison of the results to standard algorithms motivated the authors to implement it for in vivo DTI data analysis. The algorithm has been implemented to delineate fibers in two major language pathways (Broca's to SMA and Broca's to Wernicke's) across 12 healthy subjects. Though the mean of standard deviation was marginally bigger than conventional (Euler's) approach [P. J. Basser et al., "In vivo fiber tractography using DT-MRI data," Magn. Reson. Med. 44(4), 625-632 (2000)], the number of extracted fibers in this approach was significantly higher. The authors also compared the performance of the proposed method to Lu's method [Y. Lu et al., "Improved fiber tractography with Bayesian

  18. Susceptibility tensor imaging (STI) of the brain.

    Science.gov (United States)

    Li, Wei; Liu, Chunlei; Duong, Timothy Q; van Zijl, Peter C M; Li, Xu

    2017-04-01

    Susceptibility tensor imaging (STI) is a recently developed MRI technique that allows quantitative determination of orientation-independent magnetic susceptibility parameters from the dependence of gradient echo signal phase on the orientation of biological tissues with respect to the main magnetic field. By modeling the magnetic susceptibility of each voxel as a symmetric rank-2 tensor, individual magnetic susceptibility tensor elements as well as the mean magnetic susceptibility and magnetic susceptibility anisotropy can be determined for brain tissues that would still show orientation dependence after conventional scalar-based quantitative susceptibility mapping to remove such dependence. Similar to diffusion tensor imaging, STI allows mapping of brain white matter fiber orientations and reconstruction of 3D white matter pathways using the principal eigenvectors of the susceptibility tensor. In contrast to diffusion anisotropy, the main determinant factor of the susceptibility anisotropy in brain white matter is myelin. Another unique feature of the susceptibility anisotropy of white matter is its sensitivity to gadolinium-based contrast agents. Mechanistically, MRI-observed susceptibility anisotropy is mainly attributed to the highly ordered lipid molecules in the myelin sheath. STI provides a consistent interpretation of the dependence of phase and susceptibility on orientation at multiple scales. This article reviews the key experimental findings and physical theories that led to the development of STI, its practical implementations, and its applications for brain research. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  19. Current and future diagnostic tools for traumatic brain injury: CT, conventional MRI, and diffusion tensor imaging.

    Science.gov (United States)

    Brody, David L; Mac Donald, Christine L; Shimony, Joshua S

    2015-01-01

    Brain imaging plays a key role in the assessment of traumatic brain injury. In this review, we present our perspectives on the use of computed tomography (CT), conventional magnetic resonance imaging (MRI), and newer advanced modalities such as diffusion tensor imaging. Specifically, we address assessment for immediately life-threatening intracranial lesions (noncontrast head CT), assessment of progression of intracranial lesions (noncontrast head CT), documenting intracranial abnormalities for medicolegal reasons (conventional MRI with blood-sensitive sequences), presurgical planning for post-traumatic epilepsy (high spatial resolution conventional MRI), early prognostic decision making (conventional MRI with diffusion-weighted imaging), prognostic assessment for rehabilitative planning (conventional MRI and possibly diffusion tensor imaging in the future), stratification of subjects and pharmacodynamic tracking of targeted therapies in clinical trials (specific MRI sequences or positron emission tomography (PET) ligands, e.g., diffusion tensor imaging for traumatic axonal injury). We would like to emphasize that all of these methods, especially the newer research approaches, require careful radiologic-pathologic validation for optimal interpretation. We have taken this approach in a mouse model of pericontusional traumatic axonal injury. We found that the extent of reduction in the diffusion tensor imaging parameter relative anisotropy directly correlated with the number of amyloid precursor protein (APP)-stained axonal varicosities (r(2)=0.81, p<0.0001, n=20 injured mice). Interestingly, however, the least severe contusional injuries did not result in APP-stained axonal varicosities, but did cause reduction in relative anisotropy. Clearly, both the imaging assessments and the pathologic assessments will require iterative refinement. © 2015 Elsevier B.V. All rights reserved.

  20. A Review of Tensors and Tensor Signal Processing

    Science.gov (United States)

    Cammoun, L.; Castaño-Moraga, C. A.; Muñoz-Moreno, E.; Sosa-Cabrera, D.; Acar, B.; Rodriguez-Florido, M. A.; Brun, A.; Knutsson, H.; Thiran, J. P.

    Tensors have been broadly used in mathematics and physics, since they are a generalization of scalars or vectors and allow to represent more complex properties. In this chapter we present an overview of some tensor applications, especially those focused on the image processing field. From a mathematical point of view, a lot of work has been developed about tensor calculus, which obviously is more complex than scalar or vectorial calculus. Moreover, tensors can represent the metric of a vector space, which is very useful in the field of differential geometry. In physics, tensors have been used to describe several magnitudes, such as the strain or stress of materials. In solid mechanics, tensors are used to define the generalized Hooke’s law, where a fourth order tensor relates the strain and stress tensors. In fluid dynamics, the velocity gradient tensor provides information about the vorticity and the strain of the fluids. Also an electromagnetic tensor is defined, that simplifies the notation of the Maxwell equations. But tensors are not constrained to physics and mathematics. They have been used, for instance, in medical imaging, where we can highlight two applications: the diffusion tensor image, which represents how molecules diffuse inside the tissues and is broadly used for brain imaging; and the tensorial elastography, which computes the strain and vorticity tensor to analyze the tissues properties. Tensors have also been used in computer vision to provide information about the local structure or to define anisotropic image filters.

  1. Diffusion tensor imaging--arcuate fasciculus and the importance for the neurosurgeon.

    Science.gov (United States)

    Hana, Ardian; Dooms, Georges; Boecher-Schwarz, Hans; Hertel, Frank

    2015-05-01

    Tumors in eloquent areas of the brain like Broca or Wernicke might have disastrous consequences for patients. We intended to visualize the arcuate fasciculus (AF) and to demonstrate his relation with the corticospinal tract and the visual pathway using diffusion tensor imaging (DTI). We depicted between 2012 and 2014 the AF in 71 patients. Men and women of all ages were included. Eleven patients had postoperative controls also. We used a 3DT1-sequence for the navigation. Furthermore T2- and DTI-sequences were performed. The FOV was 200 × 200 mm(2), slice thickness 2mm, and an acquisition matrix of 96 × 96 yielding nearly isotropic voxels of 2 × 2 × 2 mm. 3-Tesla-MRI was carried out strictly axial using 32 gradient directions and one b0-image. We used Echo-Planar-Imaging (EPI) and ASSET parallel imaging with an acceleration factor of 2. b-Value was 800 s/mm(2). Additional scanning time was less than 9 min. AF was portrayed in 63 patients bilaterally. In one glioblastoma patient it was impossible to visualize the left AF and in seven other patients we could not portray the right one. The lesions affected AF by disrupting or displacing the fibers. DTI might be a useful tool to portray AF. It is time-saving and can be used to preserve morbidity in patients with lesions in eloquent brain areas. It might give deeper insights of the white matter and the reorganization of AF-fibers postoperatively. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Microstructural changes of the corticospinal tract in idiopathic normal pressure hydrocephalus: a comparison of diffusion tensor and diffusional kurtosis imaging

    International Nuclear Information System (INIS)

    Nakanishi, Atsushi; Hori, Masaaki; Aoki, Shigeki; Fukunaga, Issei; Masutani, Yoshitaka; Takaaki, Hattori; Miyajima, Masakazu

    2013-01-01

    The goals of this study were to examine the usefulness of diffusional kurtosis imaging (DKI) for assessing microstructural changes in the compressed corticospinal tract (CST) among patients with idiopathic normal pressure hydrocephalus (iNPH). Eleven patients with iNPH (mean age: 73.6 years, range: 65-84), who underwent 3-T magnetic resonance imaging, including DKI before surgery, were recruited. Six age-matched, healthy subjects (mean age: 69.8 years, range: 60-75) served as the control group. DKI and diffusion tensor imaging parameters were calculated and compared between the iNPH and the control groups using tract-specific analysis of the CST at the level of the lateral ventricle. Mean diffusional kurtosis (DK) and axial diffusion kurtosis were significantly lower in iNPH patients. However, apparent diffusion coefficient, fractional anisotropy, and axial eigenvalue (λ 1 ) were significantly higher in the iNPH group than in the control group. The mechanical pressure caused by ventricular enlargement in iNPH patients might induce formation of well-aligned fiber tracts and increased fiber density in the CST, resulting in decreased DK. DKI is able to depict both the altered microstructure and water molecule movement within neural axons and intra- or extracellular space. In addition, the investigated DKI parameters provide different information about white matter relative to conventional diffusional metrics for iNPH. (orig.)

  3. Microstructural changes of the corticospinal tract in idiopathic normal pressure hydrocephalus: a comparison of diffusion tensor and diffusional kurtosis imaging

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Atsushi; Hori, Masaaki; Aoki, Shigeki [Juntendo University, Department of Radiology, School of Medicine, Bunkyo-ku, Tokyo (Japan); Fukunaga, Issei [Juntendo University, Department of Radiology, School of Medicine, Bunkyo-ku, Tokyo (Japan); Tokyo Metropolitan University, Department of Health Science, Graduate School of Human Health Sciences, Arakawa, Tokyo (Japan); Masutani, Yoshitaka [The University of Tokyo, Division of Radiology and Biomedical Engineering, Graduate School of Medicine, Bunkyo-ku, Tokyo (Japan); Takaaki, Hattori [Tokyo Medical and Dental University, Department of Neurology and Neurological Science, Graduate School, Bunkyo-ku, Tokyo (Japan); Miyajima, Masakazu [Juntendo University, Department of Neurosurgery, School of Medicine, Bunkyo-ku, Tokyo (Japan)

    2013-08-15

    The goals of this study were to examine the usefulness of diffusional kurtosis imaging (DKI) for assessing microstructural changes in the compressed corticospinal tract (CST) among patients with idiopathic normal pressure hydrocephalus (iNPH). Eleven patients with iNPH (mean age: 73.6 years, range: 65-84), who underwent 3-T magnetic resonance imaging, including DKI before surgery, were recruited. Six age-matched, healthy subjects (mean age: 69.8 years, range: 60-75) served as the control group. DKI and diffusion tensor imaging parameters were calculated and compared between the iNPH and the control groups using tract-specific analysis of the CST at the level of the lateral ventricle. Mean diffusional kurtosis (DK) and axial diffusion kurtosis were significantly lower in iNPH patients. However, apparent diffusion coefficient, fractional anisotropy, and axial eigenvalue ({lambda} {sub 1}) were significantly higher in the iNPH group than in the control group. The mechanical pressure caused by ventricular enlargement in iNPH patients might induce formation of well-aligned fiber tracts and increased fiber density in the CST, resulting in decreased DK. DKI is able to depict both the altered microstructure and water molecule movement within neural axons and intra- or extracellular space. In addition, the investigated DKI parameters provide different information about white matter relative to conventional diffusional metrics for iNPH. (orig.)

  4. Diffusion tensor tractography of the mammillothalamic tract in the human brain using a high spatial resolution DTI technique.

    Science.gov (United States)

    Kamali, Arash; Zhang, Caroline C; Riascos, Roy F; Tandon, Nitin; Bonafante-Mejia, Eliana E; Patel, Rajan; Lincoln, John A; Rabiei, Pejman; Ocasio, Laura; Younes, Kyan; Hasan, Khader M

    2018-03-27

    The mammillary bodies as part of the hypothalamic nuclei are in the central limbic circuitry of the human brain. The mammillary bodies are shown to be directly or indirectly connected to the amygdala, hippocampus, and thalami as the major gray matter structures of the human limbic system. Although it is not primarily considered as part of the human limbic system, the thalamus is shown to be involved in many limbic functions of the human brain. The major direct connection of the thalami with the hypothalamic nuclei is known to be through the mammillothalamic tract. Given the crucial role of the mammillothalamic tracts in memory functions, diffusion tensor imaging may be helpful in better visualizing the surgical anatomy of this pathway noninvasively. This study aimed to investigate the utility of high spatial resolution diffusion tensor tractography for mapping the trajectory of the mammillothalamic tract in the human brain. Fifteen healthy adults were studied after obtaining written informed consent. We used high spatial resolution diffusion tensor imaging data at 3.0 T. We delineated, for the first time, the detailed trajectory of the mammillothalamic tract of the human brain using deterministic diffusion tensor tractography.

  5. Feasibility of 3.0 T diffusion-weighted nuclear magnetic resonance imaging in the evaluation of functional recovery of rats with complete spinal cord injury

    Directory of Open Access Journals (Sweden)

    Duo Zhang

    2015-01-01

    Full Text Available Diffusion tensor imaging is a sensitive way to reflect axonal necrosis and degeneration, glial cell regeneration and demyelination following spinal cord injury, and to display microstructure changes in the spinal cord in vivo. Diffusion tensor imaging technology is a sensitive method to diagnose spinal cord injury fiber tractography visualizes the white matter fibers, and directly displays the structural integrity and resultant damage of the fiber bundle. At present, diffusion tensor imaging is restricted to brain examinations, and is rarely applied in the evaluation of spinal cord injury. This study aimed to explore the fractional anisotropy and apparent diffusion coefficient of diffusion tensor magnetic resonance imaging and the feasibility of diffusion tensor tractography in the evaluation of complete spinal cord injury in rats. The results showed that the average combined scores were obviously decreased after spinal cord transection in rats, and then began to increase over time. The fractional anisotropy scores after spinal cord transection in rats were significantly lower than those in normal rats (P <0.05 the apparent diffusion coefficient was significantly increased compared with the normal group (P < 0.05. Following spinal cord transection, fractional anisotropy scores were negatively correlated with apparent diffusion coefficient values (r = -0.856, P < 0.01, and positively correlated with the average combined scores (r = 0.943, P < 0.01, while apparent diffusion coefficient values had a negative correlation with the average combined scores (r = -0.949, P < 0.01. Experimental findings suggest that, as a non-invasive examination, diffusion tensor magnetic resonance imaging can provide qualitative and quantitative information about spinal cord injury. The fractional anisotropy score and apparent diffusion coefficient have a good correlation with the average combined scores, which reflect functional recovery after spinal cord injury.

  6. The relevance of light diffusion profiles for interstitial PDT using light-diffusing optical fibers

    Science.gov (United States)

    Stringasci, Mirian D.; Fortunato, Thereza C.; Moriyama, Lilian T.; Vollet Filho, José Dirceu; Bagnato, Vanderlei S.; Kurachi, Cristina

    2017-02-01

    Photodynamic therapy (PDT) is a technique used for several tumor types treatment. Light penetration on biological tissue is one limiting factor for PDT applied to large tumors. An alternative is using interstitial PDT, in which optical fibers are inserted into tumors. Cylindrical diffusers have been used in interstitial PDT. Light emission of different diffusers depends on the manufacturing process, size and optical properties of fibers, which make difficult to establish an adequate light dosimetry, since usually light profile is not designed for direct tissue-fiber contact. This study discusses the relevance of light distribution by a cylindrical diffuser into a turbid lipid emulsion solution, and how parts of a single diffuser contribute to illumination. A 2 cm-long cylindrical diffuser optical fiber was connected to a diode laser (630 nm), and the light spatial distribution was measured by scanning the solution with a collection probe. From the light field profile generated by a 1 mm-long intermediary element of a 20 mm-long cylindrical diffuser, recovery of light distribution for the entire diffuser was obtained. PDT was performed in rat healthy liver for a real treatment outcome analysis. By using computational tools, a typical necrosis profile generated by the irradiation with such a diffuser fiber was reconstructed. The results showed that it was possible predicting theoretically the shape of a necrosis profile in a healthy, homogeneous tissue with reasonable accuracy. The ability to predict the necrosis profile obtained from an interstitial illumination by optical diffusers has the potential improve light dosimetry for interstitial PDT.

  7. Fast and Analytical EAP Approximation from a 4th-Order Tensor

    Directory of Open Access Journals (Sweden)

    Aurobrata Ghosh

    2012-01-01

    Full Text Available Generalized diffusion tensor imaging (GDTI was developed to model complex apparent diffusivity coefficient (ADC using higher-order tensors (HOTs and to overcome the inherent single-peak shortcoming of DTI. However, the geometry of a complex ADC profile does not correspond to the underlying structure of fibers. This tissue geometry can be inferred from the shape of the ensemble average propagator (EAP. Though interesting methods for estimating a positive ADC using 4th-order diffusion tensors were developed, GDTI in general was overtaken by other approaches, for example, the orientation distribution function (ODF, since it is considerably difficult to recuperate the EAP from a HOT model of the ADC in GDTI. In this paper, we present a novel closed-form approximation of the EAP using Hermite polynomials from a modified HOT model of the original GDTI-ADC. Since the solution is analytical, it is fast, differentiable, and the approximation converges well to the true EAP. This method also makes the effort of computing a positive ADC worthwhile, since now both the ADC and the EAP can be used and have closed forms. We demonstrate our approach with 4th-order tensors on synthetic data and in vivo human data.

  8. Primary progressive aphasia patients evaluated using diffusion tensor imaging and voxel based volumetry-preliminary results

    Directory of Open Access Journals (Sweden)

    Fábio Pascotto de Oliveira

    2011-06-01

    Full Text Available There are individuals who have a progressive language deficit without presenting cognitive deficits in other areas. One of the diseases related to this presentation is primary progressive aphasia (PPA. OBJECTIVE: Identify by means of diffusion tensor imaging (DTI and measurements of cortical volume, brain areas that lead to dysphasia when presenting signs of impaired connectivity or reduced volume. METHOD: Four patients with PPA were evaluated using DTI, and measurements of cortical volumes in temporal areas. These patients were compared with two normal volunteers. RESULTS: There is a trend to a difference in the number and volume of related fibers between control group and patients with PPA. Comparing cortical volumes in temporal areas between groups yielded a trend to a smaller volume in PPA patients. CONCLUSION: Patients with PPA have a trend to impairment in cortical and subcortical levels regarding relevant areas.

  9. A review of anisotropic conductivity models of brain white matter based on diffusion tensor imaging.

    Science.gov (United States)

    Wu, Zhanxiong; Liu, Yang; Hong, Ming; Yu, Xiaohui

    2018-06-01

    The conductivity of brain tissues is not only essential for electromagnetic source estimation (ESI), but also a key reflector of the brain functional changes. Different from the other brain tissues, the conductivity of whiter matter (WM) is highly anisotropic and a tensor is needed to describe it. The traditional electrical property imaging methods, such as electrical impedance tomography (EIT) and magnetic resonance electrical impedance tomography (MREIT), usually fail to image the anisotropic conductivity tensor of WM with high spatial resolution. The diffusion tensor imaging (DTI) is a newly developed technique that can fulfill this purpose. This paper reviews the existing anisotropic conductivity models of WM based on the DTI and discusses their advantages and disadvantages, as well as identifies opportunities for future research on this subject. It is crucial to obtain the linear conversion coefficient between the eigenvalues of anisotropic conductivity tensor and diffusion tensor, since they share the same eigenvectors. We conclude that the electrochemical model is suitable for ESI analysis because the conversion coefficient can be directly obtained from the concentration of ions in extracellular liquid and that the volume fraction model is appropriate to study the influence of WM structural changes on electrical conductivity. Graphical abstract ᅟ.

  10. Feasibility of Diffusion Tensor Imaging for Assessing Functional Recovery in Rats with Olfactory Ensheathing Cell Transplantation After Contusive Spinal Cord Injury (SCI).

    Science.gov (United States)

    Gu, Mengchao; Gao, Zhengchao; Li, Xiaohui; Zhao, Feng; Guo, Lei; Liu, Jiantao; He, Xijing

    2017-06-17

    BACKGROUND Olfactory ensheathing cell transplantation is a promising treatment for spinal cord injury. Diffusion tensor imaging has been applied to assess various kinds of spinal cord injury. However, it has rarely been used to evaluate the beneficial effects of olfactory ensheathing cell transplantation. This study aimed to explore the feasibility of diffusion tensor imaging in the evaluation of functional recovery in rats with olfactory ensheathing cell transplantation after contusive spinal cord injury. MATERIAL AND METHODS Immunofluorescence staining was performed to determine the purity of olfactory ensheathing cells. Rats received cell transplantation at week 1 after injury. Basso, Beattie, and Bresnahan score was used to assess the functional recovery. Magnetic resonance imaging was applied weekly, including diffusion tensor imaging. Diffusion tensor tractography was reconstructed to visualize the repair process. RESULTS The results showed that olfactory ensheathing cell transplantation increased the functional and histological recovery and restrained the secondary injury process after the initial spinal cord injury. The fractional anisotropy values in rats with cell transplantation were significantly higher than those in the control group, while the apparent diffusion coefficient values were significantly lower. Basso, Beattie, and Bresnahan score was positively and linearly correlated with fractional anisotropy value, and it was negatively and linearly correlated with apparent diffusion coefficient value. CONCLUSIONS These findings suggest that diffusion tensor imaging parameters are sensitive biomarker indices for olfactory ensheathing cell transplantation interventions, and diffusion tensor imaging scan can reflect the functional recovery promoted by the olfactory ensheathing cell transplantation after contusive spinal cord injury.

  11. Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner.

    Science.gov (United States)

    Watanabe, Makoto; Aoki, Shigeki; Masutani, Yoshitaka; Abe, Osamu; Hayashi, Naoto; Masumoto, Tomohiko; Mori, Harushi; Kabasawa, Hiroyuki; Ohtomo, Kuni

    2006-11-01

    The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections.

  12. Flexible ex vivo phantoms for validation of diffusion tensor tractography on a clinical scanner

    International Nuclear Information System (INIS)

    Watanabe, Makoto; Aoki, Shigeki; Masutani, Yoshitaka; Abe, Osamu; Hayashi, Naoto; Masumoto, Tomohiko; Mori, Harushi; Kabasawa, Hiroyuki; Ohtomo, Kuni

    2006-01-01

    The aim of this study was to develop ex vivo diffusion tensor (DT) flexible phantoms. Materials were bundles of textile threads of cotton, monofilament nylon, rayon, and polyester bunched with spiral wrapping bands and immersed in water. DT images were acquired on a 1.5-Tesla clinical magnetic resonance scanner using echo planar imaging sequences with 15 motion probing gradient directions. DT tractography with seeding and a line-tracking method was carried out by software originally developed on a PC-based workstation. We observed relatively high fractional anisotropy on the polyester phantom and were able to reconstruct tractography. Straight tracts along the bundle were displayed when it was arranged linearly. It was easy to bend arcuately or bifurcate at one end; and tracts followed the course of the bundle, whether it was curved or branched and had good agreement with direct visual observation. Tractography with the other fibers was unsuccessful. The polyester phantom revealed a diffusion anisotropic structure according to its shape and would be utilizable repeatedly under the same conditions, differently from living central neuronal system. It would be useful to validate DT sequences and to optimize an algorithm or parameters of DT tractography software. Additionally, the flexibility of the phantom would enable us to model human axonal projections. (author)

  13. Prediction of myelopathic level in cervical spondylotic myelopathy using diffusion tensor imaging.

    Science.gov (United States)

    Wang, Shu-Qiang; Li, Xiang; Cui, Jiao-Long; Li, Han-Xiong; Luk, Keith D K; Hu, Yong

    2015-06-01

    To investigate the use of a newly designed machine learning-based classifier in the automatic identification of myelopathic levels in cervical spondylotic myelopathy (CSM). In all, 58 normal volunteers and 16 subjects with CSM were recruited for diffusion tensor imaging (DTI) acquisition. The eigenvalues were extracted as the selected features from DTI images. Three classifiers, naive Bayesian, support vector machine, and support tensor machine, and fractional anisotropy (FA) were employed to identify myelopathic levels. The results were compared with clinical level diagnosis results and accuracy, sensitivity, and specificity were calculated to evaluate the performance of the developed classifiers. The accuracy by support tensor machine was the highest (93.62%) among the three classifiers. The support tensor machine also showed excellent capacity to identify true positives (sensitivity: 84.62%) and true negatives (specificity: 97.06%). The accuracy by FA value was the lowest (76%) in all the methods. The classifiers-based method using eigenvalues had a better performance in identifying the levels of CSM than the diagnosis using FA values. The support tensor machine was the best among three classifiers. © 2014 Wiley Periodicals, Inc.

  14. Outcome assessment of hemiparesis due to intracerebral hemorrhage using diffusion tensor fractional anisotropy.

    Science.gov (United States)

    Koyama, Tetsuo; Marumoto, Kohei; Uchiyama, Yuki; Miyake, Hiroji; Domen, Kazuhisa

    2015-04-01

    This study aimed to evaluate the prognostic efficacy of magnetic resonance diffusion tensor fractional anisotropy (FA) for patients with hemiparesis due to intracerebral hemorrhage. Diffusion tensor FA brain images were acquired 14-21 days after putaminal and/or thalamic hemorrhage. The ratio of FA values within the cerebral peduncles of the affected and unaffected hemispheres (rFA) was calculated for each patient (n = 40) and assessed for correlation with Brunnstrom stage (BRS, 1-6), motor component of the functional independence measure (FIM-motor, 13-91), and the total length of stay (LOS) until discharge from rehabilitation (P hemiparesis due to putaminal and/or thalamic hemorrhage, particularly hand function recovery. Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  15. 3D Representative Volume Element Reconstruction of Fiber Composites via Orientation Tensor and Substructure Features

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yi; Chen, Wei; Xu, Hongyi; Jin, Xuejun

    2016-01-01

    To provide a seamless integration of manufacturing processing simulation and fiber microstructure modeling, two new stochastic 3D microstructure reconstruction methods are proposed for two types of random fiber composites: random short fiber composites, and Sheet Molding Compounds (SMC) chopped fiber composites. A Random Sequential Adsorption (RSA) algorithm is first developed to embed statistical orientation information into 3D RVE reconstruction of random short fiber composites. For the SMC composites, an optimized Voronoi diagram based approach is developed for capturing the substructure features of SMC chopped fiber composites. The proposed methods are distinguished from other reconstruction works by providing a way of integrating statistical information (fiber orientation tensor) obtained from material processing simulation, as well as capturing the multiscale substructures of the SMC composites.

  16. Assessment of the Log-Euclidean Metric Performance in Diffusion Tensor Image Segmentation

    Directory of Open Access Journals (Sweden)

    Mostafa Charmi

    2010-06-01

    Full Text Available Introduction: Appropriate definition of the distance measure between diffusion tensors has a deep impact on Diffusion Tensor Image (DTI segmentation results. The geodesic metric is the best distance measure since it yields high-quality segmentation results. However, the important problem with the geodesic metric is a high computational cost of the algorithms based on it. The main goal of this paper is to assess the possible substitution of the geodesic metric with the Log-Euclidean one to reduce the computational cost of a statistical surface evolution algorithm. Materials and Methods: We incorporated the Log-Euclidean metric in the statistical surface evolution algorithm framework. To achieve this goal, the statistics and gradients of diffusion tensor images were defined using the Log-Euclidean metric. Numerical implementation of the segmentation algorithm was performed in the MATLAB software using the finite difference techniques. Results: In the statistical surface evolution framework, the Log-Euclidean metric was able to discriminate the torus and helix patterns in synthesis datasets and rat spinal cords in biological phantom datasets from the background better than the Euclidean and J-divergence metrics. In addition, similar results were obtained with the geodesic metric. However, the main advantage of the Log-Euclidean metric over the geodesic metric was the dramatic reduction of computational cost of the segmentation algorithm, at least by 70 times. Discussion and Conclusion: The qualitative and quantitative results have shown that the Log-Euclidean metric is a good substitute for the geodesic metric when using a statistical surface evolution algorithm in DTIs segmentation.

  17. The role of diffusion tensor imaging in brain tumor surgery : A review of the literature

    NARCIS (Netherlands)

    Potgieser, Adriaan R. E.; Wagemakers, Michiel; van Hulzen, Arjen L. J.; de Jong, Bauke M.; Hoving, Eelco W.; Groen, Rob J. M.

    Diffusion tensor imaging (DTI) is a recent technique that utilizes diffusion of water molecules to make assumptions about white matter tract architecture of the brain. Early on, neurosurgeons recognized its potential value in neurosurgical planning, as it is the only technique that offers the

  18. A voxel-based diffusion tensor imaging study of white matter in bipolar disorder.

    Science.gov (United States)

    Mahon, Katie; Wu, Jinghui; Malhotra, Anil K; Burdick, Katherine E; DeRosse, Pamela; Ardekani, Babak A; Szeszko, Philip R

    2009-05-01

    There is evidence from post-mortem and magnetic resonance imaging studies that hyperintensities, oligodendroglial abnormalities, and gross white matter volumetric alterations are involved in the pathophysiology of bipolar disorder. There is also functional imaging evidence for a defect in frontal cortico-subcortical pathways in bipolar disorder, but the white matter comprising these pathways has not been well investigated. Few studies have investigated white matter integrity in patients with bipolar disorder compared to healthy volunteers and the majority of studies have used manual region-of-interest approaches. In this study, we compared fractional anisotropy (FA) values between 30 patients with bipolar disorder and 38 healthy volunteers in the brain white matter using a voxelwise analysis following intersubject registration to Talairach space. Compared to healthy volunteers, patients demonstrated significantly (p or =50) higher FA within the right and left frontal white matter and lower FA within the left cerebellar white matter. Examination of individual eigenvalues indicated that group differences in both axial diffusivity and radial diffusivity contributed to abnormal FA within these regions. Tractography was performed in template space on averaged diffusion tensor imaging data from all individuals. Extraction of bundles passing through the clusters that differed significantly between groups suggested that white matter abnormalities along the pontine crossing tract, corticospinal/corticopontine tracts, and thalamic radiation fibers may be involved in the pathogenesis of bipolar disorder. Our findings are consistent with models of bipolar disorder that implicate dysregulation of cortico-subcortical and cerebellar regions in the disorder and may have relevance for phenomenology.

  19. In vivo reconstruction of lumbar erector spinae architecture using diffusion tensor MRI

    NARCIS (Netherlands)

    Sieben, Judith M.; Van Otten, Ilse; Lataster, Arno; Froeling, Martijn; Nederveen, Aart J.; Strijkers, Gustav J.; Drost, Maarten R.

    2016-01-01

    Study Design: Diffusion tensor magnetic resonance imaging (DTMRI) reconstruction of lumbar erector spinae (ES) compared with cadaver dissection. Objective: The aim of this study was to reconstruct the human lumbar ES from in vivo DT-MRI measurements and to compare the results with literature and

  20. Diffusion tensor imaging using multiple coils for mouse brain connectomics.

    Science.gov (United States)

    Nouls, John C; Badea, Alexandra; Anderson, Robert B J; Cofer, Gary P; Allan Johnson, G

    2018-04-19

    The correlation between brain connectivity and psychiatric or neurological diseases has intensified efforts to develop brain connectivity mapping techniques on mouse models of human disease. The neural architecture of mouse brain specimens can be shown non-destructively and three-dimensionally by diffusion tensor imaging, which enables tractography, the establishment of a connectivity matrix and connectomics. However, experiments on cohorts of animals can be prohibitively long. To improve throughput in a 7-T preclinical scanner, we present a novel two-coil system in which each coil is shielded, placed off-isocenter along the axis of the magnet and connected to a receiver circuit of the scanner. Preservation of the quality factor of each coil is essential to signal-to-noise ratio (SNR) performance and throughput, because mouse brain specimen imaging at 7 T takes place in the coil-dominated noise regime. In that regime, we show a shielding configuration causing no SNR degradation in the two-coil system. To acquire data from several coils simultaneously, the coils are placed in the magnet bore, around the isocenter, in which gradient field distortions can bias diffusion tensor imaging metrics, affect tractography and contaminate measurements of the connectivity matrix. We quantified the experimental alterations in fractional anisotropy and eigenvector direction occurring in each coil. We showed that, when the coils were placed 12 mm away from the isocenter, measurements of the brain connectivity matrix appeared to be minimally altered by gradient field distortions. Simultaneous measurements on two mouse brain specimens demonstrated a full doubling of the diffusion tensor imaging throughput in practice. Each coil produced images devoid of shading or artifact. To further improve the throughput of mouse brain connectomics, we suggested a future expansion of the system to four coils. To better understand acceptable trade-offs between imaging throughput and connectivity

  1. AGREEMENT BETWEEN THE WHITE MATTER CONNECTIVITY BASED ON THE TENSOR-BASED MORPHOMETRY AND THE VOLUMETRIC WHITE MATTER PARCELLATIONS BASED ON DIFFUSION TENSOR IMAGING

    OpenAIRE

    Kim, Seung-Goo; Lee, Hyekyoung; Chung, Moo K.; Hanson, Jamie L.; Avants, Brian B.; Gee, James C.; Davidson, Richard J.; Pollak, Seth D.

    2012-01-01

    We are interested in investigating white matter connectivity using a novel computational framework that does not use diffusion tensor imaging (DTI) but only uses T1-weighted magnetic resonance imaging. The proposed method relies on correlating Jacobian determinants across different voxels based on the tensor-based morphometry (TBM) framework. In this paper, we show agreement between the TBM-based white matter connectivity and the DTI-based white matter atlas. As an application, altered white ...

  2. An exploration of diffusion tensor eigenvector variability within human calf muscles.

    Science.gov (United States)

    Rockel, Conrad; Noseworthy, Michael D

    2016-01-01

    To explore the effect of diffusion tensor imaging (DTI) acquisition parameters on principal and minor eigenvector stability within human lower leg skeletal muscles. Lower leg muscles were evaluated in seven healthy subjects at 3T using an 8-channel transmit/receive coil. Diffusion-encoding was performed with nine signal averages (NSA) using 6, 15, and 25 directions (NDD). Individual DTI volumes were combined into aggregate volumes of 3, 2, and 1 NSA according to number of directions. Tensor eigenvalues (λ1 , λ2 , λ3 ), eigenvectors (ε1 , ε2 , ε3 ), and DTI metrics (fractional anisotropy [FA] and mean diffusivity [MD]) were calculated for each combination of NSA and NDD. Spatial maps of signal-to-noise ratio (SNR), λ3 :λ2 ratio, and zenith angle were also calculated for region of interest (ROI) analysis of vector orientation consistency. ε1 variability was only moderately related to ε2 variability (r = 0.4045). Variation of ε1 was affected by NDD, not NSA (P < 0.0002), while variation of ε2 was affected by NSA, not NDD (P < 0.0003). In terms of tensor shape, vector variability was weakly related to FA (ε1 :r = -0.1854, ε2 : ns), but had a stronger relation to the λ3 :λ2 ratio (ε1 :r = -0.5221, ε2 :r = -0.1771). Vector variability was also weakly related to SNR (ε1 :r = -0.2873, ε2 :r = -0.3483). Zenith angle was found to be strongly associated with variability of ε1 (r = 0.8048) but only weakly with that of ε2 (r = 0.2135). The second eigenvector (ε2 ) displayed higher directional variability relative to ε1 , and was only marginally affected by experimental conditions that impacted ε1 variability. © 2015 Wiley Periodicals, Inc.

  3. Silkworm Gut Fiber of Bombyx mori as an Implantable and Biocompatible Light-Diffusing Fiber

    Directory of Open Access Journals (Sweden)

    Jose Luis Cenis

    2016-07-01

    Full Text Available This work describes a new approach to the delivery of light in deeper tissues, through a silk filament that is implantable, biocompatible, and biodegradable. In the present work, silkworm gut fibers (SGFs of Bombyx mori L., are made by stretching the silk glands. Morphological, structural, and optical properties of the fibers have been characterized and the stimulatory effect of red laser light diffused from the fiber was assayed in fibroblast cultures. SGFs are formed by silk fibroin (SF mainly in a β-sheet conformation, a stable and non-soluble state in water or biological fluids. The fibers showed a high degree of transparency to visible and infrared radiation. Using a red laser (λ = 650 nm as source, the light was efficiently diffused along the fiber wall, promoting a significant increment in the cell metabolism 5 h after the irradiation. SGFs have shown their excellent properties as light-diffusing optical fibers with a stimulatory effect on cells.

  4. Region-specific connectivity in patients with periventricular nodular heterotopia and epilepsy: A study combining diffusion tensor imaging and functional MRI.

    Science.gov (United States)

    Liu, Wenyu; An, Dongmei; Tong, Xin; Niu, Running; Gong, Qiyong; Zhou, Dong

    2017-10-01

    Periventricular nodular heterotopia (PNH) is an important cause of chronic epilepsy. The purpose of this study was to evaluate region-specific connectivity in PNH patients with epilepsy and assess correlation between connectivity strength and clinical factors including duration and prognosis. Diffusion tensor imaging (DTI) and resting state functional MRI (fMRI) were performed in 28 subjects (mean age 27.4years; range 9-56years). The structural connectivity of fiber bundles passing through the manually-selected segmented nodules and other brain regions were analyzed by tractography. Cortical lobes showing functional correlations to nodules were also determined. For all heterotopic gray matter nodules, including at least one in each subject, the most frequent segments to which nodular heterotopia showed structural (132/151) and functional (146/151) connectivity were discrete regions of the ipsilateral overlying cortex. Agreement between diffusion tensor tractography and functional connectivity analyses was conserved in 81% of all nodules (122/151). In patients with longer duration or refractory epilepsy, the connectivity was significantly stronger, particularly to the frontal and temporal lobes (P<0.05). Nodules in PNH were structurally and functionally connected to the cortex. The extent is stronger in patients with longstanding or intractable epilepsy. These findings suggest the region-specific interactions may help better evaluate prognosis and seek medical or surgical interventions of PNH-related epilepsy. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Diagnosis of Lumbar Foraminal Stenosis using Diffusion Tensor Imaging

    OpenAIRE

    Eguchi, Yawara; Ohtori, Seiji; Suzuki, Munetaka; Oikawa, Yasuhiro; Yamanaka, Hajime; Tamai, Hiroshi; Kobayashi, Tatsuya; Orita, Sumihisa; Yamauchi, Kazuyo; Suzuki, Miyako; Aoki, Yasuchika; Watanabe, Atsuya; Kanamoto, Hirohito; Takahashi, Kazuhisa

    2016-01-01

    Diagnosis of lumbar foraminal stenosis remains difficult. Here, we report on a case in which bilateral lumbar foraminal stenosis was difficult to diagnose, and in which diffusion tensor imaging (DTI) was useful. The patient was a 52-year-old woman with low back pain and pain in both legs that was dominant on the right. Right lumbosacral nerve compression due to a massive uterine myoma was apparent, but the leg pain continued after a myomectomy was performed. No abnormalities were observed dur...

  6. Measuring Connectivity in the Primary Visual Pathway in Human Albinism Using Diffusion Tensor Imaging and Tractography.

    Science.gov (United States)

    Grigorian, Anahit; McKetton, Larissa; Schneider, Keith A

    2016-08-11

    In albinism, the number of ipsilaterally projecting retinal ganglion cells (RGCs) is significantly reduced. The retina and optic chiasm have been proposed as candidate sites for misrouting. Since a correlation between the number of lateral geniculate nucleus (LGN) relay neurons and LGN size has been shown, and based on previously reported reductions in LGN volumes in human albinism, we suggest that fiber projections from LGN to the primary visual cortex (V1) are also reduced. Studying structural differences in the visual system of albinism can improve the understanding of the mechanism of misrouting and subsequent clinical applications. Diffusion data and tractography are useful for mapping the OR (optic radiation). This manuscript describes two algorithms for OR reconstruction in order to compare brain connectivity in albinism and controls.An MRI scanner with a 32-channel head coil was used to acquire structural scans. A T1-weighted 3D-MPRAGE sequence with 1 mm(3) isotropic voxel size was used to generate high-resolution images for V1 segmentation. Multiple proton density (PD) weighted images were acquired coronally for right and left LGN localization. Diffusion tensor imaging (DTI) scans were acquired with 64 diffusion directions. Both deterministic and probabilistic tracking methods were run and compared, with LGN as the seed mask and V1 as the target mask. Though DTI provides relatively poor spatial resolution, and accurate delineation of OR may be challenging due to its low fiber density, tractography has been shown to be advantageous both in research and clinically. Tract based spatial statistics (TBSS) revealed areas of significantly reduced white matter integrity within the OR in patients with albinism compared to controls. Pairwise comparisons revealed a significant reduction in LGN to V1 connectivity in albinism compared to controls. Comparing both tracking algorithms revealed common findings, strengthening the reliability of the technique.

  7. Tensor-based morphometry of fibrous structures with application to human brain white matter.

    Science.gov (United States)

    Zhang, Hui; Yushkevich, Paul A; Rueckert, Daniel; Gee, James C

    2009-01-01

    Tensor-based morphometry (TBM) is a powerful approach for examining shape changes in anatomy both across populations and in time. Our work extends the standard TBM for quantifying local volumetric changes to establish both rich and intuitive descriptors of shape changes in fibrous structures. It leverages the data from diffusion tensor imaging to determine local spatial configuration of fibrous structures and combines this information with spatial transformations derived from image registration to quantify fibrous structure-specific changes, such as local changes in fiber length and in thickness of fiber bundles. In this paper, we describe the theoretical framework of our approach in detail and illustrate its application to study brain white matter. Our results show that additional insights can be gained with the proposed analysis.

  8. TU-CD-BRB-05: Radiation Damage Signature of White Matter Fiber Bundles Using Diffusion Tensor Imaging (DTI)

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, T; Chapman, C; Lawrence, T; Cao, Y [University of Michigan, Ann Arbor, MI (United States); Tsien, C [Washington University at St. Louis, St. Louis, MO (United States)

    2015-06-15

    Purpose: To develop an automated and scalable approach and identify temporal, spatial and dosimetric patterns of radiation damage of white matter (WM) fibers following partial brain irradiation. Methods: An automated and scalable approach was developed to extract DTI features of 22 major WM fibers from 33 patients with low-grade/benign tumors treated by radiation therapy (RT). DTI scans of the patients were performed pre-RT, 3- and 6-week during RT, and 1, 6 and 18 months after RT. The automated tractography analysis was applied to 198 datasets as: (1) intra-subject registration of longitudinal DTI, (2) spatial normalization of individual-patient DTI to the Johns Hopkins WM Atlas, (3) automatic fiber tracking regulated by the WM Atlas, and (4) segmentation of WM into 22 major tract profiles. Longitudinal percentage changes in fractional anisotropy (FA), and mean, axial and radial diffusivity (MD/AD/RD) of each tract from pre-RT were quantified and correlated to 95%, 90% and 80% percentiles of doses and mean doses received by the tract. Heatmaps were used to identify clusters of significant correlation and reveal temporal, spatial and dosimetric signatures of WM damage. A multivariate linear regression was further carried out to determine influence of clinical factors. Results: Of 22 tracts, AD/MD changes in 12 tracts had significant correlation with doses, especially at 6 and 18 months post-RT, indicating progressive radiation damage after RT. Most interestingly, the DTI-index changes in the elongated tracts were associated with received maximum doses, suggesting a serial-structure behavior; while short association fibers were affected by mean doses, indicating a parallel-structure response. Conclusion: Using an automated DTI-tractography analysis of whole brain WM fibers, we reveal complex radiation damage patterns of WM fibers. Damage in WM fibers that play an important role in the neural network could be associated with late neurocognitive function declines

  9. Contemporary imaging of mild TBI: the journey toward diffusion tensor imaging to assess neuronal damage.

    Science.gov (United States)

    Fox, W Christopher; Park, Min S; Belverud, Shawn; Klugh, Arnett; Rivet, Dennis; Tomlin, Jeffrey M

    2013-04-01

    To follow the progression of neuroimaging as a means of non-invasive evaluation of mild traumatic brain injury (mTBI) in order to provide recommendations based on reproducible, defined imaging findings. A comprehensive literature review and analysis of contemporary published articles was performed to study the progression of neuroimaging findings as a non-invasive 'biomarker' for mTBI. Multiple imaging modalities exist to support the evaluation of patients with mTBI, including ultrasound (US), computed tomography (CT), single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI). These techniques continue to evolve with the development of fractional anisotropy (FA), fiber tractography (FT), and diffusion tensor imaging (DTI). Modern imaging techniques, when applied in the appropriate clinical setting, may serve as a valuable tool for diagnosis and management of patients with mTBI. An understanding of modern neuroanatomical imaging will enhance our ability to analyse injury and recognize the manifestations of mTBI.

  10. Effects of MR parameter changes on the quantification of diffusion anisotropy and apparent diffusion coefficient in diffusion tensor imaging: Evaluation using a diffusional anisotropic phantom

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang Joon; Choi, Choong Gon; Kim, Jeong Kon [Dept. of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Yun, Sung Cheol [Dept. of Biostatistics, University of Ulsan College of Medicine, Seoul (Korea, Republic of); Jeong, Ha Kyu [Dept. of Radiology, East-West Neomedical Center, Kyung Hee University College of Medicine, Seoul (Korea, Republic of); Kim, Eun Ju [Clinical Scientist, MR, Philips Healthcare, Seoul (Korea, Republic of)

    2015-04-15

    To validate the usefulness of a diffusional anisotropic capillary array phantom and to investigate the effects of diffusion tensor imaging (DTI) parameter changes on diffusion fractional anisotropy (FA) and apparent diffusion coefficient (ADC) using the phantom. Diffusion tensor imaging of a capillary array phantom was performed with imaging parameter changes, including voxel size, number of sensitivity encoding (SENSE) factor, echo time (TE), number of signal acquisitions, b-value, and number of diffusion gradient directions (NDGD), one-at-a-time in a stepwise-incremental fashion. We repeated the entire series of DTI scans thrice. The coefficients of variation (CoV) were evaluated for FA and ADC, and the correlation between each MR imaging parameter and the corresponding FA and ADC was evaluated using Spearman's correlation analysis. The capillary array phantom CoVs of FA and ADC were 7.1% and 2.4%, respectively. There were significant correlations between FA and SENSE factor, TE, b-value, and NDGD, as well as significant correlations between ADC and SENSE factor, TE, and b-value. A capillary array phantom enables repeated measurements of FA and ADC. Both FA and ADC can vary when certain parameters are changed during diffusion experiments. We suggest that the capillary array phantom can be used for quality control in longitudinal or multicenter clinical studies.

  11. Delineating Neural Structures of Developmental Human Brains with Diffusion Tensor Imaging

    Directory of Open Access Journals (Sweden)

    Hao Huang

    2010-01-01

    Full Text Available The human brain anatomy is characterized by dramatic structural changes during fetal development. It is extraordinarily complex and yet its origin is a simple tubular structure. Revealing detailed anatomy at different stages of brain development not only aids in understanding this highly ordered process, but also provides clues to detect abnormalities caused by genetic or environmental factors. However, anatomical studies of human brain development during the fetal period are surprisingly scarce and histology-based atlases have become available only recently. Diffusion tensor imaging (DTI measures water diffusion to delineate the underlying neural structures. The high contrasts derived from DTI can be used to establish the brain atlas. With DTI tractography, coherent neural structures, such as white matter tracts, can be three-dimensionally reconstructed. The primary eigenvector of the diffusion tensor can be further explored to characterize microstructures in the cerebral wall of the developmental brains. In this mini-review, the application of DTI in order to reveal the structures of developmental fetal brains has been reviewed in the above-mentioned aspects. The fetal brain DTI provides a unique insight for delineating the neural structures in both macroscopic and microscopic levels. The resultant DTI database will provide structural guidance for the developmental study of human fetal brains in basic neuroscience, and reference standards for diagnostic radiology of premature newborns.

  12. On the Averaging of Cardiac Diffusion Tensor MRI Data: The Effect of Distance Function Selection

    Science.gov (United States)

    Giannakidis, Archontis; Melkus, Gerd; Yang, Guang; Gullberg, Grant T.

    2016-01-01

    Diffusion tensor magnetic resonance imaging (DT-MRI) allows a unique insight into the microstructure of highly-directional tissues. The selection of the most proper distance function for the space of diffusion tensors is crucial in enhancing the clinical application of this imaging modality. Both linear and nonlinear metrics have been proposed in the literature over the years. The debate on the most appropriate DT-MRI distance function is still ongoing. In this paper, we presented a framework to compare the Euclidean, affine-invariant Riemannian and log-Euclidean metrics using actual high-resolution DT-MRI rat heart data. We employed temporal averaging at the diffusion tensor level of three consecutive and identically-acquired DT-MRI datasets from each of five rat hearts as a means to rectify the background noise-induced loss of myocyte directional regularity. This procedure is applied here for the first time in the context of tensor distance function selection. When compared with previous studies that used a different concrete application to juxtapose the various DT-MRI distance functions, this work is unique in that it combined the following: (i) Metrics were judged by quantitative –rather than qualitative– criteria, (ii) the comparison tools were non-biased, (iii) a longitudinal comparison operation was used on a same-voxel basis. The statistical analyses of the comparison showed that the three DT-MRI distance functions tend to provide equivalent results. Hence, we came to the conclusion that the tensor manifold for cardiac DT-MRI studies is a curved space of almost zero curvature. The signal to noise ratio dependence of the operations was investigated through simulations. Finally, the “swelling effect” occurrence following Euclidean averaging was found to be too unimportant to be worth consideration. PMID:27754986

  13. On the averaging of cardiac diffusion tensor MRI data: the effect of distance function selection

    Science.gov (United States)

    Giannakidis, Archontis; Melkus, Gerd; Yang, Guang; Gullberg, Grant T.

    2016-11-01

    Diffusion tensor magnetic resonance imaging (DT-MRI) allows a unique insight into the microstructure of highly-directional tissues. The selection of the most proper distance function for the space of diffusion tensors is crucial in enhancing the clinical application of this imaging modality. Both linear and nonlinear metrics have been proposed in the literature over the years. The debate on the most appropriate DT-MRI distance function is still ongoing. In this paper, we presented a framework to compare the Euclidean, affine-invariant Riemannian and log-Euclidean metrics using actual high-resolution DT-MRI rat heart data. We employed temporal averaging at the diffusion tensor level of three consecutive and identically-acquired DT-MRI datasets from each of five rat hearts as a means to rectify the background noise-induced loss of myocyte directional regularity. This procedure is applied here for the first time in the context of tensor distance function selection. When compared with previous studies that used a different concrete application to juxtapose the various DT-MRI distance functions, this work is unique in that it combined the following: (i) metrics were judged by quantitative—rather than qualitative—criteria, (ii) the comparison tools were non-biased, (iii) a longitudinal comparison operation was used on a same-voxel basis. The statistical analyses of the comparison showed that the three DT-MRI distance functions tend to provide equivalent results. Hence, we came to the conclusion that the tensor manifold for cardiac DT-MRI studies is a curved space of almost zero curvature. The signal to noise ratio dependence of the operations was investigated through simulations. Finally, the ‘swelling effect’ occurrence following Euclidean averaging was found to be too unimportant to be worth consideration.

  14. Altered brain microstructure assessed by diffusion tensor imaging in patients with chronic pancreatitis

    DEFF Research Database (Denmark)

    Frøkjær, Jens Brøndum; Olesen, Søren Schou; Gram, Mikkel

    2011-01-01

    Objective In patients with painful chronic pancreatitis (CP) there is increasing evidence of abnormal pain processing in the central nervous system. Using magnetic resonance (MR) diffusion tensor imaging, brain microstructure in areas involved in processing of visceral pain was characterised...

  15. Diurnal microstructural variations in healthy adult brain revealed by diffusion tensor imaging.

    Directory of Open Access Journals (Sweden)

    Chunxiang Jiang

    Full Text Available Biorhythm is a fundamental property of human physiology. Changes in the extracellular space induced by cell swelling in response to the neural activity enable the in vivo characterization of cerebral microstructure by measuring the water diffusivity using diffusion tensor imaging (DTI. To study the diurnal microstructural alterations of human brain, fifteen right-handed healthy adult subjects were recruited for DTI studies in two repeated sessions (8∶30 AM and 8∶30 PM within a 24-hour interval. Fractional anisotropy (FA, apparent diffusion coefficient (ADC, axial (λ// and radial diffusivity (λ⊥ were compared pixel by pixel between the sessions for each subject. Significant increased morning measurements in FA, ADC, λ// and λ⊥ were seen in a wide range of brain areas involving frontal, parietal, temporal and occipital lobes. Prominent evening dominant λ⊥ (18.58% was detected in the right inferior temporal and ventral fusiform gyri. AM-PM variation of λ⊥ was substantially left side hemisphere dominant (p<0.05, while no hemispheric preference was observed for the same analysis for ADC (p = 0.77, λ// (p = 0.08 or FA (p = 0.25. The percentage change of ADC, λ//, λ⊥, and FA were 1.59%, 2.15%, 1.20% and 2.84%, respectively, for brain areas without diurnal diffusivity contrast. Microstructural variations may function as the substrates of the phasic neural activities in correspondence to the environment adaptation in a light-dark cycle. This research provided a baseline for researches in neuroscience, sleep medicine, psychological and psychiatric disorders, and necessitates that diurnal effect should be taken into account in following up studies using diffusion tensor quantities.

  16. Activation of less affected corticospinal tract and poor motor outcome in hemiplegic pediatric patients: a diffusion tensor tractography imaging study

    Directory of Open Access Journals (Sweden)

    Jin Hyun Kim

    2015-01-01

    Full Text Available The less affected hemisphere is important in motor recovery in mature brains. However, in terms of motor outcome in immature brains, no study has been reported on the less affected corticospinal tract in hemiplegic pediatric patients. Therefore, we examined the relationship between the condition of the less affected corticospinal tract and motor function in hemiplegic pediatric patients. Forty patients with hemiplegia due to perinatal or prenatal injury (13.7 ± 3.0 months and 40 age-matched typically developing controls were recruited. These patients were divided into two age-matched groups, the high functioning group (20 patients and the low functioning group (20 patients using functional level of hemiplegia scale. Diffusion tensor tractography images showed that compared with the control group, the patient group of the less affected corticospinal tract showed significantly increased fiber number and significantly decreased fractional anisotropy value. Significantly increased fiber number and significantly decreased fractional anisotropy value in the low functioning group were observed than in the high functioning group. These findings suggest that activation of the less affected hemisphere presenting as increased fiber number and decreased fractional anisotropy value is related to poor motor function in pediatric hemiplegic patients.

  17. AGREEMENT BETWEEN THE WHITE MATTER CONNECTIVITY BASED ON THE TENSOR-BASED MORPHOMETRY AND THE VOLUMETRIC WHITE MATTER PARCELLATIONS BASED ON DIFFUSION TENSOR IMAGING.

    Science.gov (United States)

    Kim, Seung-Goo; Lee, Hyekyoung; Chung, Moo K; Hanson, Jamie L; Avants, Brian B; Gee, James C; Davidson, Richard J; Pollak, Seth D

    2012-01-01

    We are interested in investigating white matter connectivity using a novel computational framework that does not use diffusion tensor imaging (DTI) but only uses T1-weighted magnetic resonance imaging. The proposed method relies on correlating Jacobian determinants across different voxels based on the tensor-based morphometry (TBM) framework. In this paper, we show agreement between the TBM-based white matter connectivity and the DTI-based white matter atlas. As an application, altered white matter connectivity in a clinical population is determined.

  18. Investigation of altered microstructure in patients with drug refractory epilepsy using diffusion tensor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yuwei; Yan, Xu; Fan, Mingxia [East China Normal University, Key Laboratory of Magnetic Resonance, Shanghai (China); Mao, Lingyan; Wang, Xin; Ding, Jing [Fudan University, Department of Neurology, Zhongshan Hospital, Shanghai (China); Xu, Dongrong [Columbia University and New York State Psychiatric Institute, MRI Unit/Epidemiology Division, Department of Psychiatry, New York, NY (United States)

    2017-06-15

    The risk of refractory epilepsy can be more dangerous than the adverse effect caused by medical treatment. In this study, we employed voxel-wise analysis (VWA) and tract-based spatial statistics (TBSS) methods to measure microstructural changes using diffusion tensor imaging (DTI) in patients of drug refractory epilepsy (DRE) who had been epileptic for more than 10 years. To examine the specific microstructural abnormalities in DRE patients and its difference from medically controlled epilepsy (MCE), we acquired DTI data of 7 DRE patients, 37 MCE patients, and 31 healthy controls (HCs) using a 3 T MRI scanner. Comparisons between epileptic patients and HCs between MCE and DRE patients were performed based on calculated diffusion anisotropic indices data using VWA and TBSS. Compared to HCs, epileptic patients (including MCE and DRE) showed significant DTI changes in the common affected regions based on VWA, whereas TBSS found that widespread DTI changes in parts of microstructures of bilateral hemispheres were more obvious in the DRE patients than that in the MCE patients when compared with HCs. In contrast, significant reduction of fractional anisotropy values of thalamo-cortical fibers, including left superior temporal gyrus, insular cortex, pre-/post-central gyri, and thalamus, were further found in DRE patients compared with MCE. The results of multiple diffusion anisotropic indices data provide complementary information to understand the dysfunction of thalamo-cortical pathway in DRE patients, which may be contributors to disorder of language and motor functions. Our current study may shed light on the pathophysiology of DRE. (orig.)

  19. Diffusion tensor magnetic resonance imaging driven growth modeling for radiotherapy target definition in glioblastoma.

    Science.gov (United States)

    Jensen, Morten B; Guldberg, Trine L; Harbøll, Anja; Lukacova, Slávka; Kallehauge, Jesper F

    2017-11-01

    The clinical target volume (CTV) in radiotherapy is routinely based on gadolinium contrast enhanced T1 weighted (T1w + Gd) and T2 weighted fluid attenuated inversion recovery (T2w FLAIR) magnetic resonance imaging (MRI) sequences which have been shown to over- or underestimate the microscopic tumor cell spread. Gliomas favor spread along the white matter fiber tracts. Tumor growth models incorporating the MRI diffusion tensors (DTI) allow to account more consistently for the glioma growth. The aim of the study was to investigate the potential of a DTI driven growth model to improve target definition in glioblastoma (GBM). Eleven GBM patients were scanned using T1w, T2w FLAIR, T1w + Gd and DTI. The brain was segmented into white matter, gray matter and cerebrospinal fluid. The Fisher-Kolmogorov growth model was used assuming uniform proliferation and a difference in white and gray matter diffusion of a ratio of 10. The tensor directionality was tested using an anisotropy weighting parameter set to zero (γ0) and twenty (γ20). The volumetric comparison was performed using Hausdorff distance, Dice similarity coefficient (DSC) and surface area. The median of the standard CTV (CTVstandard) was 180 cm 3 . The median surface area of CTVstandard was 211 cm 2 . The median surface area of respective CTV γ0 and CTV γ20 significantly increased to 338 and 376 cm 2 , respectively. The Hausdorff distance was greater than zero and significantly increased for both CTV γ0 and CTV γ20 with respective median of 18.7 and 25.2 mm. The DSC for both CTV γ0 and CTV γ20 were significantly below one with respective median of 0.74 and 0.72, which means that 74 and 72% of CTVstandard were included in CTV γ0 and CTV γ20, respectively. DTI driven growth models result in CTVs with a significantly increased surface area, a significantly increased Hausdorff distance and decreased overlap between the standard and model derived volume.

  20. System for diffusing light from an optical fiber or light guide

    Science.gov (United States)

    Maitland, Duncan J [Pleasant Hill, CA; Wilson, Thomas S [San Leandro, CA; Benett, William J [Livermore, CA; Small, IV, Ward [

    2008-06-10

    A system for diffusing light from an optical fiber wherein the optical fiber is coupled to a light source, comprising forming a polymer element adapted to be connected to the optical fiber and incorporating a scattering element with the polymer element wherein the scattering element diffuses the light from the polymer element. The apparatus of the present invention comprises a polymer element operatively connected to the optical fiber and a scattering element operatively connected with the shape polymer element that diffuses the light from the polymer element.

  1. Middle longitudinal fasciculus delineation within language pathways: A diffusion tensor imaging study in human

    Energy Technology Data Exchange (ETDEWEB)

    Menjot de Champfleur, Nicolas, E-mail: nicolasdechampfleur@orange.fr [Department of Neuroradiology, University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Team “Plasticity of Central Nervous System, Stem Cells and Glial Tumors,” Institut National de la Santé et de la Recherche Médicale Unité 1051, Institut of Neurosciences of Montpellier, Saint Eloi Hospital, Montpellier (France); Lima Maldonado, Igor [Department of Neuroradiology, University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Team “Plasticity of Central Nervous System, Stem Cells and Glial Tumors,” Institut National de la Santé et de la Recherche Médicale Unité 1051, Institut of Neurosciences of Montpellier, Saint Eloi Hospital, Montpellier (France); Divisão de Neurologia e Epidemiologia (CPPHO), Complexo Hospital Universitário Professor Edgard Santos, Universidade Federal da Bahia, Salvador-Bahia (Brazil); Moritz-Gasser, Sylvie [Department of Neuroradiology, University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Department of Neurology, University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Machi, Paolo [Department of Neuroradiology, University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); and others

    2013-01-15

    Introduction: The existence in the human brain of the middle longitudinal fasciculus (MdLF), initially described in the macaque monkey, is supported by diffusion tensor imaging studies. In the present work, we aim (1) to confirm that this fascicle is found constantly in control subjects with the use of DTI techniques and (2) to delineate the MdLF from the other fiber bundles that constitute the language pathways. Materials and methods: Tractography was realized in four right-handed healthy volunteers for the arcuate fascicle, uncinate fascicle, inferior fronto-occipital fascicle, inferior longitudinal fascicle and the middle longitudinal fascicle. The fiber tracts were characterized for their size, mean fractional anisotropy (FA), for their length, number of streamlines, and lateralization indices were calculated. Results: The MdLF is found constantly and it is clearly delineated from the other fascicles that constitute the language pathways, especially the ventral pathway. It runs within the superior temporal gyrus white matter from the temporal pole, then it extends caudally in the upper part of the sagittal stratum and the posterior part of the corona radiata, to reach the inferior parietal lobule (angular gyrus). We found a leftward asymmetry for all fiber tracts when considering the mean FA. Discussion: Using DTI methods, we confirm that the MdLF connects the angular gyrus and the superior temporal gyrus. On the basis of these findings, the role of the MdLF is discussed. Conclusion: The middle longitudinal fasciculus, connects the angular gyrus and the superior temporal gyrus and its course can be systematically differenciated from those of other fascicles composing both ventral and dorsal routes (IFOF, IFL, AF and UF)

  2. Middle longitudinal fasciculus delineation within language pathways: A diffusion tensor imaging study in human

    International Nuclear Information System (INIS)

    Menjot de Champfleur, Nicolas; Lima Maldonado, Igor; Moritz-Gasser, Sylvie; Machi, Paolo

    2013-01-01

    Introduction: The existence in the human brain of the middle longitudinal fasciculus (MdLF), initially described in the macaque monkey, is supported by diffusion tensor imaging studies. In the present work, we aim (1) to confirm that this fascicle is found constantly in control subjects with the use of DTI techniques and (2) to delineate the MdLF from the other fiber bundles that constitute the language pathways. Materials and methods: Tractography was realized in four right-handed healthy volunteers for the arcuate fascicle, uncinate fascicle, inferior fronto-occipital fascicle, inferior longitudinal fascicle and the middle longitudinal fascicle. The fiber tracts were characterized for their size, mean fractional anisotropy (FA), for their length, number of streamlines, and lateralization indices were calculated. Results: The MdLF is found constantly and it is clearly delineated from the other fascicles that constitute the language pathways, especially the ventral pathway. It runs within the superior temporal gyrus white matter from the temporal pole, then it extends caudally in the upper part of the sagittal stratum and the posterior part of the corona radiata, to reach the inferior parietal lobule (angular gyrus). We found a leftward asymmetry for all fiber tracts when considering the mean FA. Discussion: Using DTI methods, we confirm that the MdLF connects the angular gyrus and the superior temporal gyrus. On the basis of these findings, the role of the MdLF is discussed. Conclusion: The middle longitudinal fasciculus, connects the angular gyrus and the superior temporal gyrus and its course can be systematically differenciated from those of other fascicles composing both ventral and dorsal routes (IFOF, IFL, AF and UF)

  3. Use of diffusion tensor imaging to identify similarities and differences between cerebellar and Parkinsonism forms of multiple system atrophy

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Po-Shan [National Yang-Ming University, Department of Neurology, School of Medicine, Taipei (China); Taipei Veterans General Hospital, Neurological Institute, Taipei (China); Taipei Municipal Gan-Dau Hospital, Neurological Institute, Taipei (China); National Yang-Ming University, Institute of Brain Science, Taipei (China); Wu, Hsiu-Mei [National Yang-Ming University, Department of Neurology, School of Medicine, Taipei (China); Taipei Veterans General Hospital, Department of Radiology, Taipei (China); Lin, Ching-Po [National Yang-Ming University, Institute of Brain Science, Taipei (China); Soong, Bing-Wen [National Yang-Ming University, Department of Neurology, School of Medicine, Taipei (China); Taipei Veterans General Hospital, Neurological Institute, Taipei (China)

    2011-07-15

    We performed diffusion tensor imaging to determine if multiple system atrophy (MSA)-cerebellar (C) and MSA-Parkinsonism (P) show similar changes, as shown in pathological studies. Nineteen patients with MSA-C, 12 patients with MSA-P, 20 patients with Parkinson disease, and 20 healthy controls were evaluated with the use of voxel-based morphometry analysis of diffusion tensor imaging. There was an increase in apparent diffusion coefficient values in the middle cerebellar peduncles and cerebellum and a decrease in fractional anisotropy in the pyramidal tract, middle cerebellar peduncles, and white matter of the cerebellum in patients with MSA-C and MSA-P compared to the controls (P<0.001). In addition, isotropic diffusion-weighted image values were reduced in the cerebellar cortex and deep cerebellar nuclei in patients with MSA-C and increased in the basal ganglia in patients with MSA-P. These results indicate that despite their disparate clinical manifestations, patients with MSA-C and MSA-P share similar diffusion tensor imaging features in the infratentorial region. Further, the combination of FA, ADC and iDWI images can be used to distinguish between MSA (either form) and Parkinson disease, which has potential therapeutic implications. (orig.)

  4. Use of diffusion tensor imaging to identify similarities and differences between cerebellar and Parkinsonism forms of multiple system atrophy

    International Nuclear Information System (INIS)

    Wang, Po-Shan; Wu, Hsiu-Mei; Lin, Ching-Po; Soong, Bing-Wen

    2011-01-01

    We performed diffusion tensor imaging to determine if multiple system atrophy (MSA)-cerebellar (C) and MSA-Parkinsonism (P) show similar changes, as shown in pathological studies. Nineteen patients with MSA-C, 12 patients with MSA-P, 20 patients with Parkinson disease, and 20 healthy controls were evaluated with the use of voxel-based morphometry analysis of diffusion tensor imaging. There was an increase in apparent diffusion coefficient values in the middle cerebellar peduncles and cerebellum and a decrease in fractional anisotropy in the pyramidal tract, middle cerebellar peduncles, and white matter of the cerebellum in patients with MSA-C and MSA-P compared to the controls (P<0.001). In addition, isotropic diffusion-weighted image values were reduced in the cerebellar cortex and deep cerebellar nuclei in patients with MSA-C and increased in the basal ganglia in patients with MSA-P. These results indicate that despite their disparate clinical manifestations, patients with MSA-C and MSA-P share similar diffusion tensor imaging features in the infratentorial region. Further, the combination of FA, ADC and iDWI images can be used to distinguish between MSA (either form) and Parkinson disease, which has potential therapeutic implications. (orig.)

  5. Use of diffusion tensor imaging to identify similarities and differences between cerebellar and Parkinsonism forms of multiple system atrophy.

    Science.gov (United States)

    Wang, Po-Shan; Wu, Hsiu-Mei; Lin, Ching-Po; Soong, Bing-Wen

    2011-07-01

    We performed diffusion tensor imaging to determine if multiple system atrophy (MSA)-cerebellar (C) and MSA-Parkinsonism (P) show similar changes, as shown in pathological studies. Nineteen patients with MSA-C, 12 patients with MSA-P, 20 patients with Parkinson disease, and 20 healthy controls were evaluated with the use of voxel-based morphometry analysis of diffusion tensor imaging. There was an increase in apparent diffusion coefficient values in the middle cerebellar peduncles and cerebellum and a decrease in fractional anisotropy in the pyramidal tract, middle cerebellar peduncles, and white matter of the cerebellum in patients with MSA-C and MSA-P compared to the controls (P < 0.001). In addition, isotropic diffusion-weighted image values were reduced in the cerebellar cortex and deep cerebellar nuclei in patients with MSA-C and increased in the basal ganglia in patients with MSA-P. These results indicate that despite their disparate clinical manifestations, patients with MSA-C and MSA-P share similar diffusion tensor imaging features in the infratentorial region. Further, the combination of FA, ADC and iDWI images can be used to distinguish between MSA (either form) and Parkinson disease, which has potential therapeutic implications.

  6. Robust fiber clustering of cerebral fiber bundles in white matter

    Science.gov (United States)

    Yao, Xufeng; Wang, Yongxiong; Zhuang, Songlin

    2014-11-01

    Diffusion tensor imaging fiber tracking (DTI-FT) has been widely accepted in the diagnosis and treatment of brain diseases. During the rendering pipeline of specific fiber tracts, the image noise and low resolution of DTI would lead to false propagations. In this paper, we propose a robust fiber clustering (FC) approach to diminish false fibers from one fiber tract. Our algorithm consists of three steps. Firstly, the optimized fiber assignment continuous tracking (FACT) is implemented to reconstruct one fiber tract; and then each curved fiber in the fiber tract is mapped to a point by kernel principal component analysis (KPCA); finally, the point clouds of fiber tract are clustered by hierarchical clustering which could distinguish false fibers from true fibers in one tract. In our experiment, the corticospinal tract (CST) in one case of human data in vivo was used to validate our method. Our method showed reliable capability in decreasing the false fibers in one tract. In conclusion, our method could effectively optimize the visualization of fiber bundles and would help a lot in the field of fiber evaluation.

  7. Anatomical analysis of an aye-aye brain (Daubentonia madagascariensis, primates: Prosimii) combining histology, structural magnetic resonance imaging, and diffusion-tensor imaging.

    Science.gov (United States)

    Kaufman, Jason A; Ahrens, Eric T; Laidlaw, David H; Zhang, Song; Allman, John M

    2005-11-01

    This report presents initial results of a multimodal analysis of tissue volume and microstructure in the brain of an aye-aye (Daubentonia madagascariensis). The left hemisphere of an aye-aye brain was scanned using T2-weighted structural magnetic resonance imaging (MRI) and diffusion-tensor imaging (DTI) prior to histological processing and staining for Nissl substance and myelinated fibers. The objectives of the experiment were to estimate the volume of gross brain regions for comparison with published data on other prosimians and to validate DTI data on fiber anisotropy with histological measurements of fiber spread. Measurements of brain structure volumes in the specimen are consistent with those reported in the literature: the aye-aye has a very large brain for its body size, a reduced volume of visual structures (V1 and LGN), and an increased volume of the olfactory lobe. This trade-off between visual and olfactory reliance is likely a reflection of the nocturnal extractive foraging behavior practiced by Daubentonia. Additionally, frontal cortex volume is large in the aye-aye, a feature that may also be related to its complex foraging behavior and sensorimotor demands. Analysis of DTI data in the anterior cingulum bundle demonstrates a strong correlation between fiber spread as measured from histological sections and fiber spread as measured from DTI. These results represent the first quantitative comparison of DTI data and fiber-stained histology in the brain. (c) 2005 Wiley-Liss, Inc.

  8. Diffusion Tensor Imaging Correlates of Reading Ability in Dysfluent and Non-Impaired Readers

    Science.gov (United States)

    Lebel, Catherine; Shaywitz, Bennett; Holahan, John; Shaywitz, Sally; Marchione, Karen; Beaulieu, Christian

    2013-01-01

    Many children and adults have specific reading disabilities; insight into the brain structure underlying these difficulties is evolving from imaging. Previous research highlights the left temporal-parietal white matter as important in reading, yet the degree of involvement of other areas remains unclear. Diffusion tensor imaging (DTI) and…

  9. Data quality in diffusion tensor imaging studies of the preterm brain : a systematic review

    NARCIS (Netherlands)

    Pieterman, Kay; Plaisier, Annemarie; Govaert, Paul; Leemans, A; Lequin, Maarten H.; Dudink, Jeroen

    BACKGROUND: To study early neurodevelopment in preterm infants, evaluation of brain maturation and injury is increasingly performed using diffusion tensor imaging, for which the reliability of underlying data is paramount. OBJECTIVE: To review the literature to evaluate acquisition and processing

  10. Diffusion abnormalities of the uncinate fasciculus in Alzheimer's disease: diffusion tensor tract-specific analysis using a new method to measure the core of the tract

    Energy Technology Data Exchange (ETDEWEB)

    Yasmin, Hasina; Nakata, Yasuhiro; Abe, Osamu; Masutani, Yoshitaka; Ohtomo, Kuni [University of Tokyo, Department of Radiology, Tokyo (Japan); Aoki, Shigeki [University of Tokyo, Department of Radiology, Tokyo (Japan); Sato, Noriko [National Center of Neurology and Psychiatry, Department of Radiology, National Center Hospital for Mental, Nervous and Muscular Disorders, Tokyo (Japan); Nemoto, Kiyotaka [Ibaraki Prefectural Tomobe Hospital, Department of Psychiatry, Ibaraki (Japan); Arima, Kunimasa; Furuta, Nobuo [National Center of Neurology and Psychiatry, Department of Psychiatry, National Center Hospital for Mental, Nervous and Muscular Disorders, Tokyo (Japan); Uno, Masatake [Yoshioka Rehabilitation Clinic, Department of Psychiatry, Tokyo (Japan); Hirai, Shigeo [Iruma Hirai Clinic, Department of Psychiatry, Saitama (Japan)

    2008-04-15

    Our aim was to determine diffusion abnormalities in the uncinate fasciculus (UF) in Alzheimer's disease (AD) by diffusion tensor tractography (DTT) using a new method for measuring the core of the tract. We studied 19 patients with AD and 19 age-matched control subjects who underwent MRI using diffusion tensor imaging (DTI). DTT of the UF was generated. The mean diffusivity (MD) and fractional anisotropy (FA) of the core of the tract were measured after voxelized tract shape processing. Student's t-test was used to compare results between patients with AD and controls. Intraobserver correlation tests were also performed. FA was significantly lower (P < 0.0001) in the UF of patients with AD than of controls. There was no significant difference in MD along the UF between the two groups. Intraobserver reliability (intraclass correlation coefficient) for the first and second measurement was r > 0.93 for measured FA and r > 0.92 for measured MD. Our results suggest that FA reflects progression of AD-related histopathological changes in the UF of the white matter and may represent a useful biological index in monitoring AD. Diffusion tensor tract-specific analysis with voxelized tract shape processing to measure the core of the tract may be a sensitive tool for evaluation of diffusion abnormalities of white matter tracts in AD. (orig.)

  11. Corticospinal tract degeneration and possible pathogenesis in ALS evaluated by MR diffusion tensor imaging

    DEFF Research Database (Denmark)

    Karlsborg, Merete; Rosenbaum, Sverre; Wiegell, Mette R.

    2004-01-01

    BACKGROUND: MR diffusion tensor imaging (DTI) appears to be a powerful method to investigate the neuronal and axonal fibre distribution in the human brain. Changes in diffusion characteristics of water molecules in the white matter can be estimated as the apparent diffusion coefficient (ADC...... significance. ADC was unchanged at the level of the corona radiata. FA was significantly reduced at the lowest level (pons), only tended to be reduced in the internal capsule, but was also unchanged in the corona radiata. CONCLUSIONS: Segmentation of the CST into three regions supports the hypothesis...

  12. Diffusion tensor imaging of cingulum bundle and corpus callosum in schizophrenia vs. bipolar disorder.

    Science.gov (United States)

    Nenadić, Igor; Hoof, Anna; Dietzek, Maren; Langbein, Kerstin; Reichenbach, Jürgen R; Sauer, Heinrich; Güllmar, Daniel

    2017-08-30

    Both schizophrenia and bipolar disorder show abnormalities of white matter, as seen in diffusion tensor imaging (DTI) analyses of major brain fibre bundles. While studies in each of the two conditions have indicated possible overlap in anatomical location, there are few direct comparisons between the disorders. Also, it is unclear whether phenotypically similar subgroups (e.g. patients with bipolar disorder and psychotic features) might share white matter pathologies or be rather similar. Using region-of-interest (ROI) analysis of white matter with diffusion tensor imaging (DTI) at 3 T, we analysed fractional anisotropy (FA), radial diffusivity (RD), and apparent diffusion coefficient (ADC) of the corpus callosum and cingulum bundle in 33 schizophrenia patients, 17 euthymic (previously psychotic) bipolar disorder patients, and 36 healthy controls. ANOVA analysis showed significant main effects of group for RD and ADC (both elevated in schizophrenia). Across the corpus callosum ROIs, there was not group effect on FA, but for RD (elevated in schizophrenia, lower in bipolar disorder) and ADC (higher in schizophrenia, intermediate in bipolar disorder). Our findings show similarities and difference (some gradual) across regions of the two major fibre tracts implicated in these disorders, which would be consistent with a neurobiological overlap of similar clinical phenotypes. Copyright © 2017 Elsevier Ireland Ltd. All rights reserved.

  13. Magnetic resonance fiber density mapping of age-related white matter changes

    International Nuclear Information System (INIS)

    Stadlbauer, Andreas; Ganslandt, Oliver; Salomonowitz, Erich; Buchfelder, Michael; Hammen, Thilo; Bachmair, Johanna; Eberhardt, Knut

    2012-01-01

    Objectives: To introduce fiber density mapping (FDM) for investigation of age-related white matter (WM) changes and to compare its capabilities with conventional diffusion tensor imaging (DTI) post-processing. Methods: DTI data with 1.9 mm 3 isotropic voxels were acquired from 44 healthy volunteers (18–88 years) at 3 T. FDM is a 3-step approach which includes diagonalization of the diffusion tensor, fiber reconstruction for the whole brain, and calculation of fiber density (FD) values. Maps of fractional anisotropy (FA) and mean diffusivity (MD) were additionally calculated. Voxel-based analyses were performed to determine volume clusters of significant correlation with age. Bivariate linear regression models and Hotelling–Williams tests were used to detect significant differences between correlations. Results: FDM detected a larger WM volume affected by age-related changes concomitant with fewer significant clusters compared to FA and MD. This indicates that WM alterations due to normal aging occur rather globally than locally. FD values showed a significant stronger correlation with age in frontal lobes (prefrontal and precentral gyrus), limbic lobes (cingulate and parahippocampal gyrus), the corpus callosum (genu) and temporal lobes. Conclusions: FDM shows higher sensitivity for detection of age-related WM changes because it includes all surrounding fiber structures into the evaluation of each DTI data voxel.

  14. Magnetic resonance fiber density mapping of age-related white matter changes

    Energy Technology Data Exchange (ETDEWEB)

    Stadlbauer, Andreas, E-mail: andi@nmr.at [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, A-3100 St. Poelten (Austria); Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen (Germany); Ganslandt, Oliver [Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen (Germany); Salomonowitz, Erich [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, A-3100 St. Poelten (Austria); Buchfelder, Michael [Department of Neurosurgery, University of Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen (Germany); Hammen, Thilo [Department of Neurology, Epilepsy Center, University of Erlangen-Nuremberg, Schwabachanlage 6, D-90429 Erlangen (Germany); Bachmair, Johanna [MR Physics Group, Department of Radiology, Landesklinikum St. Poelten, Propst Fuehrer Strasse 4, A-3100 St. Poelten (Austria); Eberhardt, Knut [Krankenhaus Schloss Werneck, MRT-Kompetenzzentrum, Balthasar-Neumann-Platz 1, D-97440 Werneck (Germany)

    2012-12-15

    Objectives: To introduce fiber density mapping (FDM) for investigation of age-related white matter (WM) changes and to compare its capabilities with conventional diffusion tensor imaging (DTI) post-processing. Methods: DTI data with 1.9 mm{sup 3} isotropic voxels were acquired from 44 healthy volunteers (18–88 years) at 3 T. FDM is a 3-step approach which includes diagonalization of the diffusion tensor, fiber reconstruction for the whole brain, and calculation of fiber density (FD) values. Maps of fractional anisotropy (FA) and mean diffusivity (MD) were additionally calculated. Voxel-based analyses were performed to determine volume clusters of significant correlation with age. Bivariate linear regression models and Hotelling–Williams tests were used to detect significant differences between correlations. Results: FDM detected a larger WM volume affected by age-related changes concomitant with fewer significant clusters compared to FA and MD. This indicates that WM alterations due to normal aging occur rather globally than locally. FD values showed a significant stronger correlation with age in frontal lobes (prefrontal and precentral gyrus), limbic lobes (cingulate and parahippocampal gyrus), the corpus callosum (genu) and temporal lobes. Conclusions: FDM shows higher sensitivity for detection of age-related WM changes because it includes all surrounding fiber structures into the evaluation of each DTI data voxel.

  15. Diffusion tensor trace mapping in normal adult brain using single-shot EPI technique: A methodological study of the aging brain

    International Nuclear Information System (INIS)

    Chen, Z.G.; Hindmarsh, T.; Li, T.Q.

    2001-01-01

    Purpose: To quantify age-related changes of the average diffusion coefficient value in normal adult brain using orientation-independent diffusion tensor trace mapping and to address the methodological influences on diffusion quantification. Material and Methods: Fifty-four normal subjects (aged 20-79 years) were studied on a 1.5-T whole-body MR medical unit using a diffusion-weighted single-shot echo-planar imaging technique. Orientation-independent diffusion tensor trace maps were constructed for each subject using diffusion-weighted MR measurements in four different directions using a tetrahedral gradient combination pattern. The global average (including cerebral spinal fluid) and the tissue average of diffusion coefficients in adult brains were determined by analyzing the diffusion coefficient distribution histogram for the entire brain. Methodological influences on the measured diffusion coefficient were also investigated by comparing the results obtained using different experimental settings. Results: Both global and tissue averages of the diffusion coefficient are significantly correlated with age (p<0.03). The global average of the diffusion coefficient increases 3% per decade after the age of 40, whereas the increase in the tissue average of diffusion coefficient is about 1% per decade. Experimental settings for self-diffusion measurements, such as data acquisition methods and number of b-values, can slightly influence the statistical distribution histogram of the diffusion tensor trace and its average value. Conclusion: Increased average diffusion coefficient in adult brains with aging are consistent with findings regarding structural changes in the brain that have been associated with aging. The study also demonstrates that it is desirable to use the same experimental parameters for diffusion coefficient quantification when comparing between different subjects and groups of interest

  16. Voxel-based analysis of diffusion tensor indices in the brain in patients with Parkinson's disease

    International Nuclear Information System (INIS)

    Zhang Kaiyuan; Yu Chunshui; Zhang Yujin; Wu Xiaoli; Zhu Chaozhe; Chan Piu; Li Kuncheng

    2011-01-01

    Purpose: To investigate the abnormal diffusion in cerebral white matter and its relationship with the olfactory dysfunction in patients with Parkinson's disease (PD) through diffusion tensor imaging (DTI). Materials and methods: Diffusion tensor imaging of the cerebrum was performed in 25 patients with Parkinson's disease and 25 control subjects matched for age and sex. Differences in fractional anisotropy (FA) and mean diffusivity (MD) between these two groups were studied by voxel-based analysis of the DTI data. Correlations between diffusion indices and the olfactory function in PD patients were evaluated using the multiple regression model after controlling for the duration of the disease, Unified Parkinson's Disease Rating Sale (UPDRS), and age. Results: The damaged white and gray matter showed decreased FA or increased MD, localized bilaterally in the cerebellar and orbitofrontal cortex. In addition, in PD patients there was a positive correlation between FA values in the white matter of the left cerebellum and the thresholds of olfactory identification (TOI) and a negative correlation between MD values in the white matter of right cerebellum and the TOI. Conclusion: In patients with PD, there was disruption in the cerebellar white matter which may play an important role in the olfactory dysfunction in patients with Parkinson's disease.

  17. T2-enhanced tensor diffusion trace-weighted image in the detection of hyper-acute cerebral infarction: Comparison with isotropic diffusion-weighted image

    International Nuclear Information System (INIS)

    Chou, M.-C.; Tzeng, W.-S.; Chung, H.-W.; Wang, C.-Y.; Liu, H.-S.; Juan, C.-J.; Lo, C.-P.; Hsueh, C.-J.; Chen, C.-Y.

    2010-01-01

    Background and purpose: Although isotropic diffusion-weighted imaging (isoDWI) is very sensitive to the detection of acute ischemic stroke, it may occasionally show diffusion negative result in hyper-acute stroke. We hypothesize that high diffusion contrast diffusion trace-weighted image with enhanced T2 may improve stroke lesion conspicuity. Methods: Five hyper acute stroke patients (M:F = 0:5, average age = 61.8 ± 20.5 y/o) and 16 acute stroke patients (M:F = 11:5, average age = 67.7 ± 12 y/o) were examined six-direction tensor DWIs at b = 707 s/mm 2 . Three different diffusion-weighted images, including isotropic (isoDWI), diffusion trace-weighted image (trDWI) and T2-enhanced diffusion trace-weighted image (T2E t rDWI), were generated. Normalized lesion-to-normal ratio (nLNR) and contrast-to-noise ratio (CNR) of three diffusion images were calculated from each patient and statistically compared. Results: The trDWI shows better nLNR than isoDWI on both hyper-acute and acute stroke lesions, whereas no significant improvement in CNR. Nevertheless, the T2E t rDWI has statistically superior CNR and nLNR than those of isoDWI and trDWI in both hyper-acute and acute stroke. Conclusions: We concluded that tensor diffusion trace-weighted image with T2 enhancement is more sensitive to stroke lesion detection, and can provide higher lesion conspicuity than the conventional isotropic DWI for early stroke lesion delineation without the need of high-b-value technique.

  18. Neurite density imaging versus imaging of microscopic anisotropy in diffusion MRI: A model comparison using spherical tensor encoding.

    Science.gov (United States)

    Lampinen, Björn; Szczepankiewicz, Filip; Mårtensson, Johan; van Westen, Danielle; Sundgren, Pia C; Nilsson, Markus

    2017-02-15

    In diffusion MRI (dMRI), microscopic diffusion anisotropy can be obscured by orientation dispersion. Separation of these properties is of high importance, since it could allow dMRI to non-invasively probe elongated structures such as neurites (axons and dendrites). However, conventional dMRI, based on single diffusion encoding (SDE), entangles microscopic anisotropy and orientation dispersion with intra-voxel variance in isotropic diffusivity. SDE-based methods for estimating microscopic anisotropy, such as the neurite orientation dispersion and density imaging (NODDI) method, must thus rely on model assumptions to disentangle these features. An alternative approach is to directly quantify microscopic anisotropy by the use of variable shape of the b-tensor. Along those lines, we here present the 'constrained diffusional variance decomposition' (CODIVIDE) method, which jointly analyzes data acquired with diffusion encoding applied in a single direction at a time (linear tensor encoding, LTE) and in all directions (spherical tensor encoding, STE). We then contrast the two approaches by comparing neurite density estimated using NODDI with microscopic anisotropy estimated using CODIVIDE. Data were acquired in healthy volunteers and in glioma patients. NODDI and CODIVIDE differed the most in gray matter and in gliomas, where NODDI detected a neurite fraction higher than expected from the level of microscopic diffusion anisotropy found with CODIVIDE. The discrepancies could be explained by the NODDI tortuosity assumption, which enforces a connection between the neurite density and the mean diffusivity of tissue. Our results suggest that this assumption is invalid, which leads to a NODDI neurite density that is inconsistent between LTE and STE data. Using simulations, we demonstrate that the NODDI assumptions result in parameter bias that precludes the use of NODDI to map neurite density. With CODIVIDE, we found high levels of microscopic anisotropy in white matter

  19. Diffusion tensor imaging, white matter lesions, the corpus callosum, and gait in the elderly

    Science.gov (United States)

    Gait impairment is common in the elderly, especially affected by stroke and white matter hyper intensities found in conventional brain magnetic resonance imaging (MRI). Diffusion tensor imaging (DTI) is more sensitive to white matter damage than conventional MRI. The relationship between DTI measure...

  20. Diffusion tensor imaging correlates with lesion volume in cerebral hemisphere infarctions

    International Nuclear Information System (INIS)

    Rossi, Maija E; Jason, Eeva; Marchesotti, Silvia; Dastidar, Prasun; Ollikainen, Jyrki; Soimakallio, Seppo

    2010-01-01

    Both a large lesion volume and abnormalities in diffusion tensor imaging are independently associated with a poor prognosis after cerebral infarctions. Therefore, we assume that they are associated. This study assessed the associations between lesion volumes and diffusion tensor imaging in patients with a right-sided cerebral infarction. The lesion volumes of 33 patients (age 65.9 ± 8.7, 26 males and 7 females) were imaged using computed tomography (CT) in the acute phase (within 3-4 hours) and magnetic resonance imaging (MRI) in the chronic phase (follow-up at 12 months, with a range of 8-27 months). The chronic-phase fractional anisotropy (FA) and mean diffusivity (MD) values were measured at the site of the infarct and selected white matter tracts. Neurological tests in both the acute and chronic phases, and DTI lateralization were assessed with the Wilcoxon signed-rank test. The effects of thrombolytic therapy (n = 10) were assessed with the Mann-Whitney U test. The correlations between the measured parameters were analysed with Spearman's rho correlation. Bonferroni post-hoc correction was used to compensate for the familywise error rate in multiple comparisons. Several MD values in the right hemisphere correlated positively and FA values negatively with the lesion volumes. These correlations included both lesion area and healthy tissue. The results of the mini-mental state examination and the National Institutes of Health Stroke Scale also correlated with the lesion volume. A larger infarct volume is associated with more pronounced tissue modifications in the chronic stage as observed with the MD and FA alterations

  1. Muscle changes detected with diffusion-tensor imaging after long-distance running.

    Science.gov (United States)

    Froeling, Martijn; Oudeman, Jos; Strijkers, Gustav J; Maas, Mario; Drost, Maarten R; Nicolay, Klaas; Nederveen, Aart J

    2015-02-01

    To develop a protocol for diffusion-tensor imaging (DTI) of the complete upper legs and to demonstrate feasibility of detection of subclinical sports-related muscle changes in athletes after strenuous exercise, which remain undetected by using conventional T2-weighted magnetic resonance (MR) imaging with fat suppression. The research was approved by the institutional ethics committee review board, and the volunteers provided written consent before the study. Five male amateur long-distance runners underwent an MR examination (DTI, T1-weighted MR imaging, and T2-weighted MR imaging with fat suppression) of both upper legs 1 week before, 2 days after, and 3 weeks after they participated in a marathon. The tensor eigenvalues (λ1, λ2, and λ3), the mean diffusivity, and the fractional anisotropy (FA) were derived from the DTI data. Data per muscle from the three time-points were compared by using a two-way mixed-design analysis of variance with a Bonferroni posthoc test. The DTI protocol allowed imaging of both complete upper legs with adequate signal-to-noise ratio and within a 20-minute imaging time. After the marathon, T2-weighted MR imaging revealed grade 1 muscle strains in nine of the 180 investigated muscles. The three eigenvalues, mean diffusivity, and FA were significantly increased (P DTI measurements of the upper legs was developed that fully included frequently injured muscles, such as hamstrings, in one single imaging session. This study also revealed changes in DTI parameters that over time were not revealed by qualitative T2-weighted MR imaging with fat suppression. © RSNA, 2014.

  2. Analyzing functional, structural, and anatomical correlation of hemispheric language lateralization in healthy subjects using functional MRI, diffusion tensor imaging, and voxel-based morphometry.

    Science.gov (United States)

    James, Jija S; Kumari, Sheela R; Sreedharan, Ruma Madhu; Thomas, Bejoy; Radhkrishnan, Ashalatha; Kesavadas, Chandrasekharan

    2015-01-01

    To evaluate the efficacy of diffusion fiber tractography (DFT) and voxel-based morphometry (VBM) for lateralizing language in comparison with functional magnetic resonance imaging (fMRI) to noninvasively assess hemispheric language lateralization in normal healthy volunteers. The aim of the present study is to evaluate the concordance of language lateralization obtained by diffusion tensor imaging (DTI) and VBM to fMRI, and thus to see whether there exists an anatomical correlate for language lateralization result obtained using fMRI. This is an advanced neuroimaging study conducted in normal healthy volunteers. Fifty-seven normal healthy subjects (39 males and 18 females; age range: 15-40 years) underwent language fMRI and 30 underwent direction DTI. fMRI language laterality index (LI), fiber tract asymmetry index (AI), and tract-based statistics of dorsal and ventral language pathways were calculated. The combined results were correlated with VBM-based volumetry of Heschl's gyrus (HG), planum temporale (PT), and insula for lateralization of language function. A linear regression analysis was done to study the correlation between fMRI, DTI, and VBM measurements. A good agreement was found between language fMRI LI and fiber tract AI, more specifically for arcuate fasciculus (ArcF) and inferior longitudinal fasciculus (ILF). The study demonstrated significant correlations (P based statistics, and PT and HG volumetry for determining language lateralization. A strong one-to-one correlation between fMRI, laterality index, DTI tractography measures, and VBM-based volumetry measures for determining language lateralization exists.

  3. Regional Cerebral Disease Progression in Friedreich's Ataxia: A Longitudinal Diffusion Tensor Imaging Study.

    Science.gov (United States)

    Mascalchi, Mario; Toschi, Nicola; Giannelli, Marco; Ginestroni, Andrea; Della Nave, Riccardo; Tessa, Carlo; Piacentini, Silvia; Dotti, Maria Teresa; Aiello, Marco; Nicolai, Emanuele; Soricelli, Andrea; Salvi, Fabrizio; Diciotti, Stefano

    2016-01-01

    Imaging biomarkers of disease progression are desirable in inherited ataxias. MRI has demonstrated brain damage in Friedreich ataxia (FRDA) in form of regional atrophy of the medulla, peridentate cerebellar white matter (WM) and superior cerebellar peduncles (visible in T1-weighted images) and of change of microstructural characteristics of WM tracts of the brainstem, cerebellar peduncles, cerebellum, and supratentorial structures (visible through diffusion-weighted imaging). We explored the potential of brain MR morphometry and diffusion tensor imaging (DTI) to track the progression of neurodegeneration in FRDA. Eight patients (5F, 3M; age 13.4-41.2 years) and 8 healthy controls (2F, 6M; age 26.2-48.3 years) underwent 2 MRI examinations (mean 3.9 and 4.1 years apart, respectively) on the same 1.5T scanner. The protocol included 3D T1-weighted images and axial diffusion-weighted images (b-value 1,000 s/mm(2)) for calculating maps of fractional anisotropy, mean, axial and radial diffusivity, and mode of anisotropy. Tensor-based morphometry was used to investigate regional volume changes and tract-based spatial statistics was used to investigate microstructural changes in WM tracts. Longitudinal analyses showed no differences in regional volume changes but a significant difference in axial diffusivity changes in cerebral and corpus callosum WM of patients as compared to controls (mean longitudinal rate of change for axial diffusivity: -.02 × 10(-3) mm(2)/s/year in patients vs. .01 × 10(-3) mm(2)/s/year in controls). No correlation with number of triplets, disease duration, and worsening of the clinical deficit was observed. DTI can track brain microstructural changes in FRDA and can be considered a potential biomarker of disease progression. Copyright © 2015 by the American Society of Neuroimaging.

  4. Tensor eigenvalues and their applications

    CERN Document Server

    Qi, Liqun; Chen, Yannan

    2018-01-01

    This book offers an introduction to applications prompted by tensor analysis, especially by the spectral tensor theory developed in recent years. It covers applications of tensor eigenvalues in multilinear systems, exponential data fitting, tensor complementarity problems, and tensor eigenvalue complementarity problems. It also addresses higher-order diffusion tensor imaging, third-order symmetric and traceless tensors in liquid crystals, piezoelectric tensors, strong ellipticity for elasticity tensors, and higher-order tensors in quantum physics. This book is a valuable reference resource for researchers and graduate students who are interested in applications of tensor eigenvalues.

  5. Potential of diffusion tensor MR imaging in the assessment of cognitive impairments in children with periventricular leukomalacia born preterm

    International Nuclear Information System (INIS)

    Wang, Shanshan; Fan, Guoguang; Xu, Ke; Wang, Ci

    2013-01-01

    Purpose: To investigate MR diffusion tensor imaging (DTI) and fiber tractography (FT) in the assessment of altered major white matter fibers correlated with cognitive functions in preterm infants with periventricular leukomalacia (PVL), to explore the neural foundation for PVL children's cognitive impairments. Materials and methods: Forty six preterm infants (16 ± 4.7 months) suffered from PVL and 16 age-matched normal controls were recruited. Developmental quotient (DQ) was recorded to evaluate PVL children's cognitive functions. According to the DQ scores, patients were divided into three groups: mild, moderate and severe cognitive impairment groups. DTI scan was performed. Fractional anisotropy (FA) values of major white matter fibers were measured and their correlation with cognitive levels was evaluated. Results: Compared with the control group, the PVL group showed a significant mean FA reduction in bilateral corticospinal tract (CST), anterior/posterior limb of internal capsule (ICAL/ICPL), arcuate fasciculus (AF), corona radiate (CR), superior longitudinal fasciculus (SLF), splenium of corpus callosum (SCC) (p < 0.05) and bilateral posterior thalamic radiation (PTR) (p < 0.01). The FA values of left CST, bilateral AF, anterior cingulum (ACG), SLF, ICAL, ICPL, PTR, CR, genu of corpus callosum (GCC), SCC and middle cerebellar peduncle showed significant negative correlations with the cognitive levels. Conclusions: DTI can provide more information for understanding the pathophysiology of cognitive impairment in preterm infants with PVL

  6. Potential of diffusion tensor MR imaging in the assessment of cognitive impairments in children with periventricular leukomalacia born preterm

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shanshan, E-mail: jelly_66@126.com [Department of Radiology, The First Hospital, China Medical University, #155, Nanjing North St., Heping Dist., Shenyang, Liaoning 110001 (China); Fan, Guoguang, E-mail: cjr.fanguoguang@vip.163.com [Department of Radiology, The First Hospital, China Medical University, #155, Nanjing North St., Heping Dist., Shenyang, Liaoning 110001 (China); Xu, Ke, E-mail: cjr.xuke@vip.163.com [Department of Radiology, The First Hospital, China Medical University, #155, Nanjing North St., Heping Dist., Shenyang, Liaoning 110001 (China); Wang, Ci, E-mail: xiangxuehai19850224@yahoo.cn [Department of Radiology, The First Hospital, China Medical University, #155, Nanjing North St., Heping Dist., Shenyang, Liaoning 110001 (China)

    2013-01-15

    Purpose: To investigate MR diffusion tensor imaging (DTI) and fiber tractography (FT) in the assessment of altered major white matter fibers correlated with cognitive functions in preterm infants with periventricular leukomalacia (PVL), to explore the neural foundation for PVL children's cognitive impairments. Materials and methods: Forty six preterm infants (16 ± 4.7 months) suffered from PVL and 16 age-matched normal controls were recruited. Developmental quotient (DQ) was recorded to evaluate PVL children's cognitive functions. According to the DQ scores, patients were divided into three groups: mild, moderate and severe cognitive impairment groups. DTI scan was performed. Fractional anisotropy (FA) values of major white matter fibers were measured and their correlation with cognitive levels was evaluated. Results: Compared with the control group, the PVL group showed a significant mean FA reduction in bilateral corticospinal tract (CST), anterior/posterior limb of internal capsule (ICAL/ICPL), arcuate fasciculus (AF), corona radiate (CR), superior longitudinal fasciculus (SLF), splenium of corpus callosum (SCC) (p < 0.05) and bilateral posterior thalamic radiation (PTR) (p < 0.01). The FA values of left CST, bilateral AF, anterior cingulum (ACG), SLF, ICAL, ICPL, PTR, CR, genu of corpus callosum (GCC), SCC and middle cerebellar peduncle showed significant negative correlations with the cognitive levels. Conclusions: DTI can provide more information for understanding the pathophysiology of cognitive impairment in preterm infants with PVL.

  7. Diffusion tensor imaging and diffusion tensor imaging-fibre tractograph depict the mechanisms of Broca-like and Wernicke-like conduction aphasia.

    Science.gov (United States)

    Song, Xinjie; Dornbos, David; Lai, Zongli; Zhang, Yumei; Li, Tieshan; Chen, Hongyan; Yang, Zhonghua

    2011-06-01

    Conduction aphasia is usually considered a result of damage of the arcuate fasciculus, which is subjacent to the parietal portion of the supra-marginal gyrus and the upper part of the insula. It is important to stress that many features of conduction aphasia relate to a cortical deficit, more than a pure disconnection mechanism. In this study, we explore the mechanism of Broca-like and Wernicke-like conduction aphasia by using diffusion tensor imaging (DTI) and diffusion tensor imaging-fibre tractograph (DT-FT). We enrolled five Broca-like conduction aphasia cases, five Wernicke-like aphasia conduction cases and 10 healthy volunteers residing in Beijing and speaking Mandarin. All are right handed. We analyzed the arcuate fasciculus, Broca's areas and Wernicke's areas by DTI and measured fractional anisotrogy (FA). The results of left and right hemispheres were compared in both conduction aphasia cases and volunteers. Then the results of the conduction aphasia cases were compared with those of volunteers. The fibre construction of Broca's and Wernicke's areas was also compared by DTI-FT. The FA occupied by the identified connective pathways (Broca's area, Wernicke's area and the arcuate fasciculus) in the left hemisphere was larger than that in the right hemisphere in the control group (Paphasia cases, the FA of the left Broca's area was smaller than that of the right mirror side (PWernicke-like conduction aphasia patients, the FA of the left Wernicke's area was smaller than that of right mirror side (Paphasia results from not only arcuate fasciculus destruction, but also from disruption of the associated cortical areas. Along different segments of the arcuate fasciculus, the characteristics of language disorders of conduction aphasia were different. A lesion involving Broca's area and the anterior segments of the arcuate fasciculus would lead to Broca-like conduction aphasia, whereas a lesion involved Wernicke's area and posterior segments of the arcuate fasciculus

  8. Assessment of arcuate fasciculus with diffusion-tensor tractography may predict the prognosis of aphasia in patients with left middle cerebral artery infarcts

    Energy Technology Data Exchange (ETDEWEB)

    Hosomi, Akiko; Nagakane, Yoshinari; Kuriyama, Nagato; Mizuno, Toshiki; Nakagawa, Masanori [Kyoto Prefectural University of Medicine, Department of Neurology, Graduate School of Medical Science, Kyoto (Japan); Yamada, Kei; Nishimura, Tsunehiko [Kyoto Prefectural University of Medicine, Department of Radiology, Graduate School of Medical Science, Kyoto (Japan)

    2009-09-15

    It is often clinically difficult to assess the severity of aphasia in the earliest stage of cerebral infarction. A method enabling objective assessment of verbal function is needed for this purpose. We examined whether diffusion tensor (DT) tractography is of clinical value in assessing aphasia. Thirteen right-handed patients with left middle cerebral artery infarcts who were scanned within 2 days after stroke onset were enrolled in this study. Magnetic resonance data of ten control subjects were also examined by DT tractography. Based on the severity of aphasia at discharge, patients were divided into two groups: six patients in the aphasic group and seven in the nonaphasic group. Fractional anisotropy (FA) and number of arcuate fasciculus fibers were evaluated. Asymmetry index was calculated for both FA and number of fibers. FA values for the arcuate fasciculus fibers did not differ between hemispheres in either the patient groups or the controls. Number of arcuate fasciculus fibers exhibited a significant leftward asymmetry in the controls and the nonaphasic group but not in the aphasic group. Asymmetry index of number of fibers was significantly lower (rightward) in the aphasic group than in the nonaphasic (P = 0.015) and control (P = 0.005) groups. Loss of leftward asymmetry in number of AF fibers predicted aphasia at discharge with a sensitivity of 0.83 and specificity of 0.86. Asymmetry of arcuate fasciculus fibers by DT tractography may deserve to be assessed in acute infarction for predicting the fate of vascular aphasia. (orig.)

  9. Assessment of arcuate fasciculus with diffusion-tensor tractography may predict the prognosis of aphasia in patients with left middle cerebral artery infarcts

    International Nuclear Information System (INIS)

    Hosomi, Akiko; Nagakane, Yoshinari; Kuriyama, Nagato; Mizuno, Toshiki; Nakagawa, Masanori; Yamada, Kei; Nishimura, Tsunehiko

    2009-01-01

    It is often clinically difficult to assess the severity of aphasia in the earliest stage of cerebral infarction. A method enabling objective assessment of verbal function is needed for this purpose. We examined whether diffusion tensor (DT) tractography is of clinical value in assessing aphasia. Thirteen right-handed patients with left middle cerebral artery infarcts who were scanned within 2 days after stroke onset were enrolled in this study. Magnetic resonance data of ten control subjects were also examined by DT tractography. Based on the severity of aphasia at discharge, patients were divided into two groups: six patients in the aphasic group and seven in the nonaphasic group. Fractional anisotropy (FA) and number of arcuate fasciculus fibers were evaluated. Asymmetry index was calculated for both FA and number of fibers. FA values for the arcuate fasciculus fibers did not differ between hemispheres in either the patient groups or the controls. Number of arcuate fasciculus fibers exhibited a significant leftward asymmetry in the controls and the nonaphasic group but not in the aphasic group. Asymmetry index of number of fibers was significantly lower (rightward) in the aphasic group than in the nonaphasic (P = 0.015) and control (P = 0.005) groups. Loss of leftward asymmetry in number of AF fibers predicted aphasia at discharge with a sensitivity of 0.83 and specificity of 0.86. Asymmetry of arcuate fasciculus fibers by DT tractography may deserve to be assessed in acute infarction for predicting the fate of vascular aphasia. (orig.)

  10. Application of fiber tractography for neurosurgery

    International Nuclear Information System (INIS)

    Hashimoto, Naoya; Yoshimine, Toshiki

    2007-01-01

    This review describes about the fiber tractography (FT) for its basic principle, method, and application to neurosurgery involving usefulness, pitfall, validation needed and future perspective. MR diffusion weighted image exhibits the diffusion (Brownian movement) of water molecules and its multiple images taken by different angles of magnetic field can also give information of their diffusion anisotropy, whereby diffusion tensor image is yielded as FT owing to their high anisotropy, with use of appropriate softwares assuming an ellipsoid of anisotropic water (single tensor model). FT thus presents an image of a specific and functional neurofiber bundle. Recently, FT in neurosurgery has been recognized to have pitfalls in tracing the bundle at its crossing and branch, e.g., suggested avoidance of surgery of eloquent area navigated with FT alone. For this, developed and considered are the multi-tensor models based on multiple ellipsoids and on probabilistic one on probability, and combination of electrophysiological mapping is thought necessary as well. Application of FT is also actively in progress to understand neurological diseases like cerebral vascular lesion, hemiplegia, epilepsy, injury and many others. FT navigation without other validation is thus limited in neurosurgery, but FT is surely one of means to improve patients' prognosis and quality of life (QOL). (R.T.)

  11. Changes of brain microstructure in patients with painful chronic pancreatitis assessed by diffusion tensor imaging

    DEFF Research Database (Denmark)

    Frøkjær, Jens Brøndum; Olesen, Søren Schou; Gram, Mikkel

    Objective In patients with painful chronic pancreatitis (CP) there is increasing evidence of abnormal pain processing in the central nervous system. Using magnetic resonance (MR) diffusion tensor imaging, brain microstructure in areas involved in processing of visceral pain was characterised...

  12. Injury of the inferior cerebellar peduncle in patients with mild traumatic brain injury: A diffusion tensor tractography study.

    Science.gov (United States)

    Jang, Sung Ho; Yi, Ji Hyun; Kwon, Hyeok Gyu

    2016-01-01

    No study on injury of the inferior cerebellar peduncle (ICP) in patients with mild traumatic brain injury (mTBI) has been reported. This study, using diffusion tensor tractography (DTT), attempted to demonstrate injury of the ICP in patients with mTBI. Three patients with mTBI resulting from a car accident and 18 normal healthy control subjects were enrolled in this study. Diffusion tensor imaging data were acquired at 2 months (patient 1) and 3 months (patients 2 and 3) after onset and the ICP was reconstructed. The Balance Error Scoring System was used for evaluation of balance at the same time diffusion tensor imaging scanning was performed. The ICPs were discontinued at the upper portion of the vertical cerebellar branch and the transverse cerebellar branch (patient 1) and the proximal portion of the transverse cerebellar branch (patients 2 and 3) compared to the normal control subjects. Regarding DTT parameters, in the three patients, the fibre number of the ICPs was decreased by more than 2 SD compared with those of subjects in the control group. Evaluation of the ICP using DTT would be useful in patients with a balance problem after mTBI.

  13. An efficient explicit numerical scheme for diffusion-type equations with a highly inhomogeneous and highly anisotropic diffusion tensor

    International Nuclear Information System (INIS)

    Larroche, O.

    2007-01-01

    A locally split-step explicit (LSSE) algorithm was developed for efficiently solving a multi-dimensional advection-diffusion type equation involving a highly inhomogeneous and highly anisotropic diffusion tensor, which makes the problem very ill-conditioned for standard implicit methods involving the iterative solution of large linear systems. The need for such an optimized algorithm arises, in particular, in the frame of thermonuclear fusion applications, for the purpose of simulating fast charged-particle slowing-down with an ion Fokker-Planck code. The LSSE algorithm is presented in this paper along with the results of a model slowing-down problem to which it has been applied

  14. CUDA-Accelerated Geodesic Ray-Tracing for Fiber Tracking

    Directory of Open Access Journals (Sweden)

    Evert van Aart

    2011-01-01

    Full Text Available Diffusion Tensor Imaging (DTI allows to noninvasively measure the diffusion of water in fibrous tissue. By reconstructing the fibers from DTI data using a fiber-tracking algorithm, we can deduce the structure of the tissue. In this paper, we outline an approach to accelerating such a fiber-tracking algorithm using a Graphics Processing Unit (GPU. This algorithm, which is based on the calculation of geodesics, has shown promising results for both synthetic and real data, but is limited in its applicability by its high computational requirements. We present a solution which uses the parallelism offered by modern GPUs, in combination with the CUDA platform by NVIDIA, to significantly reduce the execution time of the fiber-tracking algorithm. Compared to a multithreaded CPU implementation of the same algorithm, our GPU mapping achieves a speedup factor of up to 40 times.

  15. Glioma grade assessment by using histogram analysis of diffusion tensor imaging-derived maps

    International Nuclear Information System (INIS)

    Jakab, Andras; Berenyi, Ervin; Molnar, Peter; Emri, Miklos

    2011-01-01

    Current endeavors in neuro-oncology include morphological validation of imaging methods by histology, including molecular and immunohistochemical techniques. Diffusion tensor imaging (DTI) is an up-to-date methodology of intracranial diagnostics that has gained importance in studies of neoplasia. Our aim was to assess the feasibility of discriminant analysis applied to histograms of preoperative diffusion tensor imaging-derived images for the prediction of glioma grade validated by histomorphology. Tumors of 40 consecutive patients included 13 grade II astrocytomas, seven oligoastrocytomas, six grade II oligodendrogliomas, three grade III oligoastrocytomas, and 11 glioblastoma multiformes. Preoperative DTI data comprised: unweighted (B 0 ) images, fractional anisotropy, longitudinal and radial diffusivity maps, directionally averaged diffusion-weighted imaging, and trace images. Sampling consisted of generating histograms for gross tumor volumes; 25 histogram bins per scalar map were calculated. The histogram bins that allowed the most precise determination of low-grade (LG) or high-grade (HG) classification were selected by multivariate discriminant analysis. Accuracy of the model was defined by the success rate of the leave-one-out cross-validation. Statistical descriptors of voxel value distribution did not differ between LG and HG tumors and did not allow classification. The histogram model had 88.5% specificity and 85.7% sensitivity in the separation of LG and HG gliomas; specificity was improved when cases with oligodendroglial components were omitted. Constructing histograms of preoperative radiological images over the tumor volume allows representation of the grade and enables discrimination of LG and HG gliomas which has been confirmed by histopathology. (orig.)

  16. Feasibility of creating a high-resolution 3D diffusion tensor imaging based atlas of the human brainstem: a case study at 11.7 T.

    Science.gov (United States)

    Aggarwal, Manisha; Zhang, Jiangyang; Pletnikova, Olga; Crain, Barbara; Troncoso, Juan; Mori, Susumu

    2013-07-01

    A three-dimensional stereotaxic atlas of the human brainstem based on high resolution ex vivo diffusion tensor imaging (DTI) is introduced. The atlas consists of high resolution (125-255 μm isotropic) three-dimensional DT images of the formalin-fixed brainstem acquired at 11.7 T. The DTI data revealed microscopic neuroanatomical details, allowing three-dimensional visualization and reconstruction of fiber pathways including the decussation of the pyramidal tract fibers, and interdigitating fascicles of the corticospinal and transverse pontine fibers. Additionally, strong gray-white matter contrasts in the apparent diffusion coefficient (ADC) maps enabled precise delineation of gray matter nuclei in the brainstem, including the cranial nerve and the inferior olivary nuclei. Comparison with myelin-stained histology shows that at the level of resolution achieved in this study, the structural details resolved with DTI contrasts in the brainstem were comparable to anatomical delineation obtained with histological sectioning. Major neural structures delineated from DTI contrasts in the brainstem are segmented and three-dimensionally reconstructed. Further, the ex vivo DTI data are nonlinearly mapped to a widely-used in vivo human brain atlas, to construct a high-resolution atlas of the brainstem in the Montreal Neurological Institute (MNI) stereotaxic coordinate space. The results demonstrate the feasibility of developing a 3D DTI based atlas for detailed characterization of brainstem neuroanatomy with high resolution and contrasts, which will be a useful resource for research and clinical applications. Copyright © 2013 Elsevier Inc. All rights reserved.

  17. UNC-Utah NA-MIC framework for DTI fiber tract analysis.

    Science.gov (United States)

    Verde, Audrey R; Budin, Francois; Berger, Jean-Baptiste; Gupta, Aditya; Farzinfar, Mahshid; Kaiser, Adrien; Ahn, Mihye; Johnson, Hans; Matsui, Joy; Hazlett, Heather C; Sharma, Anuja; Goodlett, Casey; Shi, Yundi; Gouttard, Sylvain; Vachet, Clement; Piven, Joseph; Zhu, Hongtu; Gerig, Guido; Styner, Martin

    2014-01-01

    Diffusion tensor imaging has become an important modality in the field of neuroimaging to capture changes in micro-organization and to assess white matter integrity or development. While there exists a number of tractography toolsets, these usually lack tools for preprocessing or to analyze diffusion properties along the fiber tracts. Currently, the field is in critical need of a coherent end-to-end toolset for performing an along-fiber tract analysis, accessible to non-technical neuroimaging researchers. The UNC-Utah NA-MIC DTI framework represents a coherent, open source, end-to-end toolset for atlas fiber tract based DTI analysis encompassing DICOM data conversion, quality control, atlas building, fiber tractography, fiber parameterization, and statistical analysis of diffusion properties. Most steps utilize graphical user interfaces (GUI) to simplify interaction and provide an extensive DTI analysis framework for non-technical researchers/investigators. We illustrate the use of our framework on a small sample, cross sectional neuroimaging study of eight healthy 1-year-old children from the Infant Brain Imaging Study (IBIS) Network. In this limited test study, we illustrate the power of our method by quantifying the diffusion properties at 1 year of age on the genu and splenium fiber tracts.

  18. Diffusion tensor magnetic resonance imaging of the pancreas.

    Directory of Open Access Journals (Sweden)

    Noam Nissan

    Full Text Available To develop a diffusion-tensor-imaging (DTI protocol that is sensitive to the complex diffusion and perfusion properties of the healthy and malignant pancreas tissues.Twenty-eight healthy volunteers and nine patients with pancreatic-ductal-adenocacinoma (PDAC, were scanned at 3T with T2-weighted and DTI sequences. Healthy volunteers were also scanned with multi-b diffusion-weighted-imaging (DWI, whereas a standard clinical protocol complemented the PDAC patients' scans. Image processing at pixel resolution yielded parametric maps of three directional diffusion coefficients λ1, λ2, λ3, apparent diffusion coefficient (ADC, and fractional anisotropy (FA, as well as a λ1-vector map, and a main diffusion-direction map.DTI measurements of healthy pancreatic tissue at b-values 0,500 s/mm² yielded: λ1 = (2.65±0.35×10⁻³, λ2 = (1.87±0.22×10⁻³, λ3 = (1.20±0.18×10⁻³, ADC = (1.91±0.22×10⁻³ (all in mm²/s units and FA = 0.38±0.06. Using b-values of 100,500 s/mm² led to a significant reduction in λ1, λ2, λ3 and ADC (p<.0001 and a significant increase (p<0.0001 in FA. The reduction in the diffusion coefficients suggested a contribution of a fast intra-voxel-incoherent-motion (IVIM component at b≤100 s/mm², which was confirmed by the multi-b DWI results. In PDACs, λ1, λ2, λ3 and ADC in both 0,500 s/mm² and 100,500 s/mm² b-values sets, as well as the reduction in these diffusion coefficients between the two sets, were significantly lower in comparison to the distal normal pancreatic tissue, suggesting higher cellularity and diminution of the fast-IVIM component in the cancer tissue.DTI using two reference b-values 0 and 100 s/mm² enabled characterization of the water diffusion and anisotropy of the healthy pancreas, taking into account a contribution of IVIM. The reduction in the diffusion coefficients of PDAC, as compared to normal pancreatic tissue, and the smaller change in these coefficients in PDAC

  19. Diffusion tensor magnetic resonance imaging of the breast: a pilot study

    International Nuclear Information System (INIS)

    Baltzer, Pascal A.T.; Schaefer, Anja; Dietzel, Matthias; Kaiser, Werner A.; Graessel, David; Gajda, Mieczyslaw; Camara, Oumar

    2011-01-01

    Diffusion-weighted MR imaging has shown diagnostic value for differential diagnosis of breast lesions. Diffusion tensor imaging (DTI) adds information about tissue microstructure by addressing diffusion direction. We have examined the diagnostic application of DTI of the breast. A total of 59 patients (71 lesions: 54 malignant, 17 benign) successfully underwent prospective echo planar imaging-DTI (EPI-DTI) (1.5 T). First, diffusion direction both of parenchyma as well as lesions was assessed on parametric maps. Subsequently, apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were measured. Statistics included univariate (Mann-Whitney U test, receiver operating analysis) and multivariate (logistic regression analysis, LRA) tests. Main diffusion direction of parenchyma was anterior-posterior in the majority of cases (66.1%), whereas lesions (benign, malignant) showed no predominant diffusion direction in the majority of cases (23.9%). ADC values showed highest differences between benign and malignant lesions (P < 0.001) with resulting area under the curve (AUC) of 0.899. FA values were lower in benign (interquartile range, IR, 0.14-0.24) compared to malignant lesions (IR 0.21-0.35, P < 0.002) with an AUC of 0.751-0.770. Following LRA, FA did not prove to have incremental value for differential diagnosis over ADC values. Microanatomical differences between benign and malignant breast lesions as well as breast parenchyma can be visualized by using DTI. (orig.)

  20. Motion-robust diffusion tensor acquisition at routine 3T magnetic resonance imaging

    International Nuclear Information System (INIS)

    Yasmin, Hasina; Abe, Osamu; Masutani, Yoshitaka; Hayashi, Naoto; Ohtomo, Kuni; Kabasawa, Hiroyuki; Aoki, Shigeki

    2010-01-01

    We compared different acquisition and reconstruction methods in phantom and human studies in the clinical setting to validate our hypothesis that optimizing the k-space acquisition and reconstruction method could decrease motion artifacts. Diffusion tensor images of a water phantom were obtained with three table displacement magnitudes: 1 mm, 2 mm, and 3 mm. Images were reconstructed using homodyne and zero-fill reconstruction. Overscanning in 8- and 16-k y lines was tested. We performed visual assessment of the artifacts using reconstructed coronal images and analyzed them with Wilcoxon signed-ranks test both for phantom and human studies. Also, fractional anisotropy (FA) changes between acquisition methods were compared. Artifacts due to smaller displacement (1 and 2 mm) were significantly reduced in 16-k y overscan with zero filling. The Wilcoxon signed-ranks test showed significant differences (P<0.031 for reconstruction methods and P<0.016 for overscanning methods). FA changes were statistically significant (P<0.037; Student's t-test). The Wilcoxon signed-ranks test showed significant reductions (P<0.005) in the human study. Motion-induced artifacts can be reduced by optimizing acquisition and reconstruction methods. The techniques described in this study offer an effective method for robust estimation of diffusion tensor in the presence of motion-related artifactual data points. (author)

  1. Simultaneous analysis and quality assurance for diffusion tensor imaging.

    Directory of Open Access Journals (Sweden)

    Carolyn B Lauzon

    Full Text Available Diffusion tensor imaging (DTI enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio. However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70% while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA

  2. Neuropsychological Correlates of Diffusion Tensor Imaging in Schizophrenia

    Science.gov (United States)

    Nestor, Paul G.; Kubicki, Marek; Gurrera, Ronald J.; Niznikiewicz, Margaret; Frumin, Melissa; McCarley, Robert W.; Shenton, Martha E.

    2009-01-01

    Patients with schizophrenia (n = 41) and healthy comparison participants (n = 46) completed neuropsychological measures of intelligence, memory, and executive function. A subset of each group also completed magnetic resonance diffusion tensor imaging (DTI) studies (fractional anisotropy and cross-sectional area) of the uncinate fasciculus (UF) and cingulate bundle (CB). Patients with schizophrenia showed reduced levels of functioning across all neuropsychological measures. In addition, selective neuropsychological–DTI relationships emerged. Among patients but not controls, lower levels of declarative–episodic verbal memory correlated with reduced left UF, whereas executive function errors related to performance monitoring correlated with reduced left CB. The data suggested abnormal DTI patterns linking declarative–episodic verbal memory deficits to the left UF and executive function deficits to the left CB among patients with schizophrenia. PMID:15506830

  3. Normal development of human brain white matter from infancy to early adulthood: a diffusion tensor imaging study.

    Science.gov (United States)

    Uda, Satoshi; Matsui, Mie; Tanaka, Chiaki; Uematsu, Akiko; Miura, Kayoko; Kawana, Izumi; Noguchi, Kyo

    2015-01-01

    Diffusion tensor imaging (DTI), which measures the magnitude of anisotropy of water diffusion in white matter, has recently been used to visualize and quantify parameters of neural tracts connecting brain regions. In order to investigate the developmental changes and sex and hemispheric differences of neural fibers in normal white matter, we used DTI to examine 52 healthy humans ranging in age from 2 months to 25 years. We extracted the following tracts of interest (TOIs) using the region of interest method: the corpus callosum (CC), cingulum hippocampus (CGH), inferior longitudinal fasciculus (ILF), and superior longitudinal fasciculus (SLF). We measured fractional anisotropy (FA), apparent diffusion coefficient (ADC), axial diffusivity (AD), and radial diffusivity (RD). Approximate values and changes in growth rates of all DTI parameters at each age were calculated and analyzed using LOESS (locally weighted scatterplot smoothing). We found that for all TOIs, FA increased with age, whereas ADC, AD and RD values decreased with age. The turning point of growth rates was at approximately 6 years. FA in the CC was greater than that in the SLF, ILF and CGH. Moreover, FA, ADC and AD of the splenium of the CC (sCC) were greater than in the genu of the CC (gCC), whereas the RD of the sCC was lower than the RD of the gCC. The FA of right-hemisphere TOIs was significantly greater than that of left-hemisphere TOIs. In infants, growth rates of both FA and RD were larger than those of AD. Our data show that developmental patterns differ by TOIs and myelination along with the development of white matter, which can be mainly expressed as an increase in FA together with a decrease in RD. These findings clarify the long-term normal developmental characteristics of white matter microstructure from infancy to early adulthood. © 2015 S. Karger AG, Basel.

  4. Diffusion tensor imaging parameters' changes of cerebellar hemispheres in Parkinson's disease

    Energy Technology Data Exchange (ETDEWEB)

    Mormina, Enricomaria; Arrigo, Alessandro; Granata, Francesca; Anastasi, Giuseppe P.; Gaeta, Michele [University of Messina, Department of Biomedical Science and Morphological and Functional Images, Messina (Italy); Calamuneri, Alessandro; Quartarone, Angelo [University of Messina, Department of Neurosciences, Messina (Italy); Ghilardi, Maria F.; Inglese, Matilde; Di Rocco, Alessandro [Mount Sinai Hospital, New York, NY (United States); Milardi, Demetrio [University of Messina, Department of Biomedical Science and Morphological and Functional Images, Messina (Italy); IRCCS Centro Neurolesi Bonino Pulejo, Messina (Italy)

    2015-03-01

    Studies with diffusion tensor imaging (DTI) analysis have produced conflicting information about the involvement of the cerebellar hemispheres in Parkinson's disease (PD). We, thus, used a new approach for the analysis of DTI parameters in order to ascertain the involvement of the cerebellum in PD. We performed a fiber tract-based analysis of cerebellar peduncles and cerebellar hemispheres in 16 healthy subjects and in 16 PD patients with more than 5 years duration of disease, using a 3T MRI scanner and a constrained spherical deconvolution (CSD) approach for tractographic reconstructions. In addition, we performed statistical analysis of DTI parameters and fractional anisotropy (FA) XYZ direction samplings. We found a statistically significant decrement of FA values in PD patients compared to controls (p < 0.05). In addition, extrapolating and analyzing FA XYZ direction samplings for each patient and each control, we found that this result was due to a stronger decrement of FA values along the Y axis (antero-posterior direction) (p < 0.01); FA changes along X and Z axes were not statistically significant (p > 0.05). We confirmed also no statistically significant differences of FA and apparent diffusion coefficient (ADC) for cerebellar peduncles in PD patients compared to healthy controls. The DTI-based cerebellar abnormalities in PD could constitute an advance in the knowledge of this disease. We demonstrated a statistically significant reduction of FA in cerebellar hemispheres of PD patients compared to healthy controls. Our work also demonstrated that the use of more sophisticated approaches in the DTI parameter analysis could potentially have a clinical relevance. (orig.)

  5. Diffusion tensor imaging parameters' changes of cerebellar hemispheres in Parkinson's disease

    International Nuclear Information System (INIS)

    Mormina, Enricomaria; Arrigo, Alessandro; Granata, Francesca; Anastasi, Giuseppe P.; Gaeta, Michele; Calamuneri, Alessandro; Quartarone, Angelo; Ghilardi, Maria F.; Inglese, Matilde; Di Rocco, Alessandro; Milardi, Demetrio

    2015-01-01

    Studies with diffusion tensor imaging (DTI) analysis have produced conflicting information about the involvement of the cerebellar hemispheres in Parkinson's disease (PD). We, thus, used a new approach for the analysis of DTI parameters in order to ascertain the involvement of the cerebellum in PD. We performed a fiber tract-based analysis of cerebellar peduncles and cerebellar hemispheres in 16 healthy subjects and in 16 PD patients with more than 5 years duration of disease, using a 3T MRI scanner and a constrained spherical deconvolution (CSD) approach for tractographic reconstructions. In addition, we performed statistical analysis of DTI parameters and fractional anisotropy (FA) XYZ direction samplings. We found a statistically significant decrement of FA values in PD patients compared to controls (p < 0.05). In addition, extrapolating and analyzing FA XYZ direction samplings for each patient and each control, we found that this result was due to a stronger decrement of FA values along the Y axis (antero-posterior direction) (p < 0.01); FA changes along X and Z axes were not statistically significant (p > 0.05). We confirmed also no statistically significant differences of FA and apparent diffusion coefficient (ADC) for cerebellar peduncles in PD patients compared to healthy controls. The DTI-based cerebellar abnormalities in PD could constitute an advance in the knowledge of this disease. We demonstrated a statistically significant reduction of FA in cerebellar hemispheres of PD patients compared to healthy controls. Our work also demonstrated that the use of more sophisticated approaches in the DTI parameter analysis could potentially have a clinical relevance. (orig.)

  6. Cognitive functions, electroencephalographic and diffusion tensor imaging changes in children with active idiopathic epilepsy.

    Science.gov (United States)

    A Yassine, Imane; M Eldeeb, Waleed; A Gad, Khaled; A Ashour, Yossri; A Yassine, Inas; O Hosny, Ahmed

    2018-07-01

    Neurocognitive impairment represents one of the most common comorbidities occurring in children with idiopathic epilepsy. Diagnosis of the idiopathic form of epilepsy requires the absence of any macrostructural abnormality in the conventional MRI. Though changes can be seen at the microstructural level imaged using advanced techniques such as the Diffusion Tensor Imaging (DTI). The aim of this work is to study the correlation between the microstructural white matter DTI findings, the electroencephalographic changes and the cognitive dysfunction in children with active idiopathic epilepsy. A comparative cross-sectional study, included 60 children with epilepsy based on the Stanford-Binet 5th Edition Scores was conducted. Patients were equally assigned to normal cognitive function or cognitive dysfunction groups. The history of the epileptic condition was gathered via personal interviews. All patients underwent brain Electroencephalography (EEG) and DTI, which was analyzed using FSL. The Fractional Anisotropy (FA) was significantly higher whereas the Mean Diffusivity (MD) was significantly lower in the normal cognitive function group than in the cognitive dysfunction group. This altered microstructure was related to the degree of the cognitive performance of the studied children with epilepsy. The microstructural alterations of the neural fibers in children with epilepsy and cognitive dysfunction were significantly related to the younger age of onset of epilepsy, the poor control of the clinical seizures, and the use of multiple antiepileptic medications. Children with epilepsy and normal cognitive functions differ in white matter integrity, measured using DTI, compared with children with cognitive dysfunction. These changes have important cognitive consequences. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Tensor estimation for double-pulsed diffusional kurtosis imaging.

    Science.gov (United States)

    Shaw, Calvin B; Hui, Edward S; Helpern, Joseph A; Jensen, Jens H

    2017-07-01

    Double-pulsed diffusional kurtosis imaging (DP-DKI) represents the double diffusion encoding (DDE) MRI signal in terms of six-dimensional (6D) diffusion and kurtosis tensors. Here a method for estimating these tensors from experimental data is described. A standard numerical algorithm for tensor estimation from conventional (i.e. single diffusion encoding) diffusional kurtosis imaging (DKI) data is generalized to DP-DKI. This algorithm is based on a weighted least squares (WLS) fit of the signal model to the data combined with constraints designed to minimize unphysical parameter estimates. The numerical algorithm then takes the form of a quadratic programming problem. The principal change required to adapt the conventional DKI fitting algorithm to DP-DKI is replacing the three-dimensional diffusion and kurtosis tensors with the 6D tensors needed for DP-DKI. In this way, the 6D diffusion and kurtosis tensors for DP-DKI can be conveniently estimated from DDE data by using constrained WLS, providing a practical means for condensing DDE measurements into well-defined mathematical constructs that may be useful for interpreting and applying DDE MRI. Data from healthy volunteers for brain are used to demonstrate the DP-DKI tensor estimation algorithm. In particular, representative parametric maps of selected tensor-derived rotational invariants are presented. Copyright © 2017 John Wiley & Sons, Ltd.

  8. Diffusion tensor imaging of the anterior cruciate ligament graft.

    Science.gov (United States)

    Van Dyck, Pieter; Froeling, Martijn; De Smet, Eline; Pullens, Pim; Torfs, Michaël; Verdonk, Peter; Sijbers, Jan; Parizel, Paul M; Jeurissen, Ben

    2017-11-01

    A great need exists for objective biomarkers to assess graft healing following ACL reconstruction to guide the time of return to sports. The purpose of this study was to evaluate the feasibility and reliability of diffusion tensor imaging (DTI) to delineate the anterior cruciate ligament (ACL) graft and to investigate its diffusion properties using a clinical 3T scanner. DTI of the knee (b = 0, 400, and 800 s/mm 2 , 10 diffusion directions, repeated 16 times for a total of 336 diffusion-weighted volumes) was performed at 3T in 17 patients between 3 and 7 months (mean, 4 months) following ACL reconstruction. Tractography was performed by two independent observers to delineate the ACL graft. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) were calculated within the graft. Interrater reliability was assessed using the intraclass correlation coefficient (ICC) and the scan-rescan reproducibility was evaluated based on the percentage coefficient of variance (%CV) across 20 repetition bootknife samples. In all subjects, tractography of the ACL graft was feasible. Quantitative evaluation of the diffusion properties of the ACL graft yielded the following mean ± SD values: FA = 0.23 ± 0.04; MD = 1.30 ± 0.11 × 10 -3 mm 2 /s; AD = 1.61 ± 0.12 × 10 -3 mm 2 /s, and RD = 1.15 ± 0.11 × 10 -3 mm 2 /s. Interrater reliability for the DTI parameters was excellent (ICC = 0.91-0.98). Mean %CVs for FA, MD, AD, and RD were 4.6%, 3.5%, 3.7%, and 4.4%, respectively. We demonstrated the feasibility and reliability of DTI for the visualization and quantitative evaluation of the ACL graft at 3T. 3 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2017;46:1423-1432. © 2017 International Society for Magnetic Resonance in Medicine.

  9. Diffusion imaging and tractography of congenital brain malformations

    International Nuclear Information System (INIS)

    Wahl, Michael; Barkovich, A.J.; Mukherjee, Pratik

    2010-01-01

    Diffusion imaging is an MRI modality that measures the microscopic molecular motion of water in order to investigate white matter microstructure. The modality has been used extensively in recent years to investigate the neuroanatomical basis of congenital brain malformations. We review the basic principles of diffusion imaging and of specific techniques, including diffusion tensor imaging (DTI) and high angular resolution diffusion imaging (HARDI). We show how DTI and HARDI, and their application to fiber tractography, has elucidated the aberrant connectivity underlying a number of congenital brain malformations. Finally, we discuss potential uses for diffusion imaging of developmental disorders in the clinical and research realms. (orig.)

  10. Impact of Gradient Number and Voxel Size on Diffusion Tensor Imaging Tractography for Resective Brain Surgery

    NARCIS (Netherlands)

    Hoefnagels, Friso W. A.; de Witt Hamer, Philip C.; Pouwels, Petra J. W.; Barkhof, Frederik; Vandertop, W. Peter

    2017-01-01

    To explore quantitatively and qualitatively how the number of gradient directions (NGD) and spatial resolution (SR) affect diffusion tensor imaging (DTI) tractography in patients planned for brain tumor surgery, using routine clinical magnetic resonance imaging protocols. Of 67 patients with

  11. Voxel-based analysis of diffusion tensor indices in the brain in patients with Parkinson's disease

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Kaiyuan, E-mail: kaiyuanzhang@yahoo.cn [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Key Laboratory of Neurodegenerative Diseases, Capital Medical University, Ministry of Education (China); Yu Chunshui, E-mail: chunshuiyu826@yahoo.com.cn [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Key Laboratory of Neurodegenerative Diseases, Capital Medical University, Ministry of Education (China); Zhang Yujin, E-mail: zyjinjin@gmail.com [State Key Laboratory of Cognitive Neurosciences and Learning, Beijing Normal University, Beijing 100875 (China); Wu Xiaoli, E-mail: wendy2006315@126.com [Key Laboratory of Neurodegenerative Diseases, Capital Medical University, Ministry of Education (China) and Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Zhu Chaozhe, E-mail: czzhu@bnu.edu.cn [State Key Laboratory of Cognitive Neurosciences and Learning, Beijing Normal University, Beijing 100875 (China); Chan Piu, E-mail: pbchan@bjsap.org [Key Laboratory of Neurodegenerative Diseases, Capital Medical University, Ministry of Education (China); Department of Neurology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Li Kuncheng, E-mail: likuncheng1955@yahoo.com.cn [Department of Radiology, Xuanwu Hospital, Capital Medical University, Beijing 100053 (China); Key Laboratory of Neurodegenerative Diseases, Capital Medical University, Ministry of Education (China)

    2011-02-15

    Purpose: To investigate the abnormal diffusion in cerebral white matter and its relationship with the olfactory dysfunction in patients with Parkinson's disease (PD) through diffusion tensor imaging (DTI). Materials and methods: Diffusion tensor imaging of the cerebrum was performed in 25 patients with Parkinson's disease and 25 control subjects matched for age and sex. Differences in fractional anisotropy (FA) and mean diffusivity (MD) between these two groups were studied by voxel-based analysis of the DTI data. Correlations between diffusion indices and the olfactory function in PD patients were evaluated using the multiple regression model after controlling for the duration of the disease, Unified Parkinson's Disease Rating Sale (UPDRS), and age. Results: The damaged white and gray matter showed decreased FA or increased MD, localized bilaterally in the cerebellar and orbitofrontal cortex. In addition, in PD patients there was a positive correlation between FA values in the white matter of the left cerebellum and the thresholds of olfactory identification (TOI) and a negative correlation between MD values in the white matter of right cerebellum and the TOI. Conclusion: In patients with PD, there was disruption in the cerebellar white matter which may play an important role in the olfactory dysfunction in patients with Parkinson's disease.

  12. Diffusion Tensor Imaging of Normal-Appearing White Matter as Biomarker for Radiation-Induced Late Delayed Cognitive Decline

    International Nuclear Information System (INIS)

    Chapman, Christopher H.; Nagesh, Vijaya; Sundgren, Pia C.; Buchtel, Henry; Chenevert, Thomas L.; Junck, Larry; Lawrence, Theodore S.; Tsien, Christina I.; Cao, Yue

    2012-01-01

    Purpose: To determine whether early assessment of cerebral white matter degradation can predict late delayed cognitive decline after radiotherapy (RT). Methods and Materials: Ten patients undergoing conformal fractionated brain RT participated in a prospective diffusion tensor magnetic resonance imaging study. Magnetic resonance imaging studies were acquired before RT, at 3 and 6 weeks during RT, and 10, 30, and 78 weeks after starting RT. The diffusivity variables in the parahippocampal cingulum bundle and temporal lobe white matter were computed. A quality-of-life survey and neurocognitive function tests were administered before and after RT at the magnetic resonance imaging follow-up visits. Results: In both structures, longitudinal diffusivity (λ ‖ ) decreased and perpendicular diffusivity (λ ⊥ ) increased after RT, with early changes correlating to later changes (p ⊥ at 3 weeks, and patients with >50% of cingula volume receiving >12 Gy had a greater increase in λ ⊥ at 3 and 6 weeks (p ‖ (30 weeks, p ‖ changes predicted for post-RT changes in verbal recall scores (3 and 6 weeks, p < .05). The neurocognitive test scores correlated significantly with the quality-of-life survey results. Conclusions: The correlation between early diffusivity changes in the parahippocampal cingulum and the late decline in verbal recall suggests that diffusion tensor imaging might be useful as a biomarker for predicting late delayed cognitive decline.

  13. Dynamics of chaotic maps for modelling the multifractal spectrum of human brain Diffusion Tensor Images

    International Nuclear Information System (INIS)

    Provata, A.; Katsaloulis, P.; Verganelakis, D.A.

    2012-01-01

    Highlights: ► Calculation of human brain multifractal spectra. ► Calculations are based on Diffusion Tensor MRI Images. ► Spectra are modelled by coupled Ikeda map dynamics. ► Coupled lattice Ikeda maps model well only positive multifractal spectra. ► Appropriately modified coupled lattice Ikeda maps give correct spectra. - Abstract: The multifractal spectra of 3d Diffusion Tensor Images (DTI) obtained by magnetic resonance imaging of the human brain are studied. They are shown to deviate substantially from artificial brain images with the same white matter intensity. All spectra, obtained from 12 healthy subjects, show common characteristics indicating non-trivial moments of the intensity. To model the spectra the dynamics of the chaotic Ikeda map are used. The DTI multifractal spectra for positive q are best approximated by 3d coupled Ikeda maps in the fully developed chaotic regime. The coupling constants are as small as α = 0.01. These results reflect not only the white tissue non-trivial architectural complexity in the human brain, but also demonstrate the presence and importance of coupling between neuron axons. The architectural complexity is also mirrored by the deviations in the negative q-spectra, where the rare events dominate. To obtain a good agreement in the DTI negative q-spectrum of the brain with the Ikeda dynamics, it is enough to slightly modify the most rare events of the coupled Ikeda distributions. The representation of Diffusion Tensor Images with coupled Ikeda maps is not unique: similar conclusions are drawn when other chaotic maps (Tent, Logistic or Henon maps) are employed in the modelling of the neuron axons network.

  14. Elucidating fluctuating diffusivity in center-of-mass motion of polymer models with time-averaged mean-square-displacement tensor

    Science.gov (United States)

    Miyaguchi, Tomoshige

    2017-10-01

    There have been increasing reports that the diffusion coefficient of macromolecules depends on time and fluctuates randomly. Here a method is developed to elucidate this fluctuating diffusivity from trajectory data. Time-averaged mean-square displacement (MSD), a common tool in single-particle-tracking (SPT) experiments, is generalized to a second-order tensor with which both magnitude and orientation fluctuations of the diffusivity can be clearly detected. This method is used to analyze the center-of-mass motion of four fundamental polymer models: the Rouse model, the Zimm model, a reptation model, and a rigid rodlike polymer. It is found that these models exhibit distinctly different types of magnitude and orientation fluctuations of diffusivity. This is an advantage of the present method over previous ones, such as the ergodicity-breaking parameter and a non-Gaussian parameter, because with either of these parameters it is difficult to distinguish the dynamics of the four polymer models. Also, the present method of a time-averaged MSD tensor could be used to analyze trajectory data obtained in SPT experiments.

  15. Connectivity-enhanced diffusion analysis reveals white matter density disruptions in first episode and chronic schizophrenia

    Directory of Open Access Journals (Sweden)

    Rachael G. Grazioplene

    Full Text Available Reduced fractional anisotropy (FA is a well-established correlate of schizophrenia, but it remains unclear whether these tensor-based differences are the result of axon damage and/or organizational changes and whether the changes are progressive in the adult course of illness. Diffusion MRI data were collected in 81 schizophrenia patients (54 first episode and 27 chronic and 64 controls. Analysis of FA was combined with “fixel-based” analysis, the latter of which leverages connectivity and crossing-fiber information to assess both fiber bundle density and organizational complexity (i.e., presence and magnitude of off-axis diffusion signal. Compared with controls, patients with schizophrenia displayed clusters of significantly lower FA in the bilateral frontal lobes, right dorsal centrum semiovale, and the left anterior limb of the internal capsule. All FA-based group differences overlapped substantially with regions containing complex fiber architecture. FA within these clusters was positively correlated with principal axis fiber density, but inversely correlated with both secondary/tertiary axis fiber density and voxel-wise fiber complexity. Crossing fiber complexity had the strongest (inverse association with FA (r = −0.82. When crossing fiber structure was modeled in the MRtrix fixel-based analysis pipeline, patients exhibited significantly lower fiber density compared to controls in the dorsal and posterior corpus callosum (central, postcentral, and forceps major. Findings of lower FA in patients with schizophrenia likely reflect two inversely related signals: reduced density of principal axis fiber tracts and increased off-axis diffusion sources. Whereas the former confirms at least some regions where myelin and or/axon count are lower in schizophrenia, the latter indicates that the FA signal from principal axis fiber coherence is broadly contaminated by macrostructural complexity, and therefore does not necessarily reflect

  16. Diffusion formation and psychiatric diseases

    International Nuclear Information System (INIS)

    Reith, W.; Kulikovski, J.

    2015-01-01

    The basic principle behind diffusion is Brownian motion. The diffusion parameters obtained in a clinical association provide information on the spatial distribution of water molecule mobility and, therefore, evidence of the morphological integrity of the white and grey matters of the brain. In recent years functional magnetic resonance imaging (fMRI) could contribute to obtaining a detailed understanding of the cortical and subcortical cerebral networks. Diffusion tensor imaging (DTI) investigations can demonstrate the extent of anisotropy and the fiber pathways in so-called parametric images. For example, in Alzheimer's disease DTI reveals a reduced structural connectivity between the posterior cingulum and the hippocampus. This article shows examples of the application of diffusion-weighted imaging (DWI) in psychiatric disorders. (orig.) [de

  17. Utility of diffusion tensor imaging tractography in decision making for extratemporal resective epilepsy surgery.

    Science.gov (United States)

    Radhakrishnan, Ashalatha; James, Jija S; Kesavadas, Chandrasekharan; Thomas, Bejoy; Bahuleyan, Biji; Abraham, Mathew; Radhakrishnan, Kurupath

    2011-11-01

    To assess the utility of diffusion tensor imaging tractography (DTIT) in decision making in patients considered for extratemporal resective epilepsy surgery. We subjected 49 patients with drug-resistant focal seizures due to lesions located in frontal, parietal and occipital lobes to DTIT to map the white matter fiber anatomy in relation to the planned resection zone, in addition to routine presurgical evaluation. We stratified our patients preoperatively into different grades of risk for anticipated neurological deficits as judged by the distance of the white matter tracts from the resection zones and functional cortical areas. Thirty-seven patients underwent surgery; surgery was abandoned in 12 (24.5%) patients because of the high risk of postoperative neurological deficit. DTIT helped us to modify the surgical procedures in one-fourth of occipital, one-third of frontal, and two-thirds of parietal and multilobar resections. Overall, DTIT assisted us in surgical decision making in two-thirds of our patients. DTIT is a noninvasive imaging strategy that can be used effectively in planning resection of epileptogenic lesions at or close to eloquent cortical areas. DTIT helps in predicting postoperative neurological outcome and thereby assists in surgical decision making and in preoperative counseling of patients with extratemporal focal epilepsies. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Fast diffusion tensor magnetic resonance imaging of the mouse brain at ultrahigh-field: aiming at cohort studies.

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    Hans-Peter Müller

    Full Text Available INTRODUCTION: In-vivo high resolution diffusion tensor imaging (DTI of the mouse brain is often limited by the low signal to noise ratio (SNR resulting from the required small voxel sizes. Recently, cryogenically cooled resonators (CCR have demonstrated significant increase of the effective SNR. It is the objective of this study to enable fast DTI of the mouse brain. In this context, CCRs appear attractive for SNR improvement. METHODS: Three mice underwent a DTI examination at 156²×250 µm³ spatial resolution with a CCR at ultrahigh field (11.7T. Diffusion images were acquired along 30 gradient directions plus 5 references without diffusion encoding, resulting in a total acquisition time of 35 minutes. For comparison, mice additionally underwent a standardized 110 minutes acquisition protocol published earlier. Fractional anisotropy (FA and fiber tracking (FT results including quantitative tractwise fractional anisotropy statistics (TFAS were qualitatively and quantitatively compared. RESULTS: Qualitative and quantitative assessment of the calculated fractional anisotropy maps and fibre tracking results showed coinciding outcome comparing 35 minute scans to the standardized 110 minute scan. Coefficients of variation for ROI-based FA-comparison as well as for TFAS revealed comparable results for the different scanning protocols. CONCLUSION: Mouse DTI at 11.7 T was performed with an acquisition time of approximately 30 minutes, which is considered feasible for cohort studies. The rapid acquisition protocol reveals reliable and reproducible FA-values and FT reconstructions, thus allowing an experimental setup for in-vivo large scale whole brain murine DTI cohort studies.

  19. White Matter Integrity in Asperger Syndrome: A Preliminary Diffusion Tensor Magnetic Resonance Imaging Study in Adults

    NARCIS (Netherlands)

    Bloemen, Oswald J. N.; Deeley, Quinton; Sundram, Fred; Daly, Eileen M.; Barker, Gareth J.; Jones, Derek K.; van Amelsvoort, Therese A. M. J.; Schmitz, Nicole; Robertson, Dene; Murphy, Kieran C.; Murphy, Declan G. M.

    2010-01-01

    Background: Autistic Spectrum Disorder (ASD), including Asperger syndrome and autism, is a highly genetic neurodevelopmental disorder. There is a consensus that ASD has a biological basis, and it has been proposed that it is a "connectivity" disorder. Diffusion Tensor Magnetic Resonance Imaging

  20. Evidence of a middle longitudinal fasciculus in the human brain from fiber dissection

    Science.gov (United States)

    Maldonado, Igor Lima; de Champfleur, Nicolas Menjot; Velut, Stéphane; Destrieux, Christophe; Zemmoura, Ilyess; Duffau, Hugues

    2013-01-01

    A rostrocaudal pathway connecting the temporal and parietal lobes was described in monkeys using autoradiography and was named the middle longitudinal fasciculus (MdLF). Recently, the use of diffusion tensor tractography has allowed it to be depicted in human volunteers. In the present study, a technique of fiber dissection was used in 18 cadaveric human brains to investigate the presence of this fasciculus and to detail its anatomical relationships. On the basis of our findings, fiber dissection provides evidence for a long horizontal bundle medial to the arcuate fasciculus and extending to the superior temporal gyrus. Its fibers occupy the lateral-most layer of the upper portion of the stratum sagittale and partially cover the inferior fronto-occipital fasciculus, which is situated deeper and slightly inferiorly. Whereas MdLF fibers continue on a relatively superficial level to reach the superior temporal gyrus, the inferior fronto-occipital fasciculus penetrates the deep temporal white matter and crosses the insular lobe. Although diffusion tensor imaging suggests that the MdLF terminates in the angular gyrus, this was not confirmed by the present study. These long association fibers continue onward posteriorly into upper portions of the occipital lobe. Further studies are needed to understand the role of the MdLF in brain function. PMID:23621438

  1. Harmonization of multi-site diffusion tensor imaging data.

    Science.gov (United States)

    Fortin, Jean-Philippe; Parker, Drew; Tunç, Birkan; Watanabe, Takanori; Elliott, Mark A; Ruparel, Kosha; Roalf, David R; Satterthwaite, Theodore D; Gur, Ruben C; Gur, Raquel E; Schultz, Robert T; Verma, Ragini; Shinohara, Russell T

    2017-11-01

    Diffusion tensor imaging (DTI) is a well-established magnetic resonance imaging (MRI) technique used for studying microstructural changes in the white matter. As with many other imaging modalities, DTI images suffer from technical between-scanner variation that hinders comparisons of images across imaging sites, scanners and over time. Using fractional anisotropy (FA) and mean diffusivity (MD) maps of 205 healthy participants acquired on two different scanners, we show that the DTI measurements are highly site-specific, highlighting the need of correcting for site effects before performing downstream statistical analyses. We first show evidence that combining DTI data from multiple sites, without harmonization, may be counter-productive and negatively impacts the inference. Then, we propose and compare several harmonization approaches for DTI data, and show that ComBat, a popular batch-effect correction tool used in genomics, performs best at modeling and removing the unwanted inter-site variability in FA and MD maps. Using age as a biological phenotype of interest, we show that ComBat both preserves biological variability and removes the unwanted variation introduced by site. Finally, we assess the different harmonization methods in the presence of different levels of confounding between site and age, in addition to test robustness to small sample size studies. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Towards the use of bioresorbable fibers in time-domain diffuse optics.

    Science.gov (United States)

    Di Sieno, Laura; Boetti, Nadia G; Dalla Mora, Alberto; Pugliese, Diego; Farina, Andrea; Konugolu Venkata Sekar, Sanathana; Ceci-Ginistrelli, Edoardo; Janner, Davide; Pifferi, Antonio; Milanese, Daniel

    2018-01-01

    In the last years bioresorbable materials are gaining increasing interest for building implantable optical components for medical devices. In this work we show the fabrication of bioresorbable optical fibers designed for diffuse optics applications, featuring large core diameter (up to 200 μm) and numerical aperture (0.17) to maximize the collection efficiency of diffused light. We demonstrate the suitability of bioresorbable fibers for time-domain diffuse optical spectroscopy firstly checking the intrinsic performances of the setup by acquiring the instrument response function. We then validate on phantoms the use of bioresorbable fibers by applying the MEDPHOT protocol to assess the performance of the system in measuring optical properties (namely, absorption and scattering coefficients) of homogeneous media. Further, we show an ex-vivo validation on a chicken breast by measuring the absorption and scattering spectra in the 500-1100 nm range using interstitially inserted bioresorbable fibers. This work represents a step toward a new way to look inside the body using optical fibers that can be implanted in patients. These fibers could be useful either for diagnostic (e. g. for monitoring the evolution after surgical interventions) or treatment (e. g. photodynamic therapy) purposes. Picture: Microscopy image of the 100 μm core bioresorbable fiber. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Diffusion tensor imaging differentiates vascular parkinsonism from parkinsonian syndromes of degenerative origin in elderly subjects

    Energy Technology Data Exchange (ETDEWEB)

    Deverdun, Jérémy [Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Laboratoire Charles Coulomb, CNRS UMR 5221 - Université Montpellier II, Montpellier (France); I2FH, Institut d’Imagerie Fonctionnelle Humaine, Hôpital Gui de Chauliac, CHRU de, Montpellier (France); Menjot de Champfleur, Sophie [Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Clinique du Parc, Castelnau-le-Lez (France); Cabello-Aguilar, Simon [Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); I2FH, Institut d’Imagerie Fonctionnelle Humaine, Hôpital Gui de Chauliac, CHRU de, Montpellier (France); Maury, Florence [Department of Neurology, Montpellier University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Molino, François [Laboratoire Charles Coulomb, CNRS UMR 5221 - Université Montpellier II, Montpellier (France); Institut de Génomique Fonctionnelle, UMR 5203 - INSERM U661 - Université Montpellier II - Université, Montpellier I (France); Charif, Mahmoud [Department of Neurology, Montpellier University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Leboucq, Nicolas [Department of Neuroradiology, Montpellier University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); Ayrignac, Xavier; Labauge, Pierre [Department of Neurology, Montpellier University Hospital Center, Gui de Chauliac Hospital, Montpellier (France); and others

    2014-11-15

    Background and Purpose: The etiologic diagnosis of parkinsonian syndromes is of particular importance when considering syndromes of vascular or degenerative origin. The purpose of this study is to find differences in the white-matter architecture between those two groups in elderly patients. Materials and Methods: Thirty-five patients were prospectively included (multiple-system atrophy, n = 5; Parkinson's disease, n = 15; progressive supranuclear palsy, n = 9; vascular parkinsonism, n = 6), with a mean age of 76 years. Patients with multiple-system atrophy, progressive supranuclear palsy and Parkinson's disease were grouped as having parkinsonian syndromes of degenerative origin. Brain MRIs included diffusion tensor imaging. Fractional anisotropy and mean-diffusivity maps were spatially normalized, and group analyses between parkinsonian syndromes of degenerative origin and vascular parkinsonism were performed using a voxel-based approach. Results: Statistical parametric-mapping analysis of diffusion tensor imaging data showed decreased fractional anisotropy value in internal capsules bilaterally in patients with vascular parkinsonism compared to parkinsonian syndromes of degenerative origin (p = 0.001) and showed a lower mean diffusivity in the white matter of the left superior parietal lobule (p = 0.01). Fractional anisotropy values were found decreased in the middle cerebellar peduncles in multiple-system atrophy compared to Parkinson's disease and progressive supranuclear palsy. The mean diffusivity was increased in those regions for these subgroups. Conclusion: Clinically defined vascular parkinsonism was associated with decreased fractional anisotropy in the deep white matter (internal capsules) compared to parkinsonian syndromes of degenerative origin. These findings are consistent with previously published neuropathological data.

  4. Diffusion tensor imaging differentiates vascular parkinsonism from parkinsonian syndromes of degenerative origin in elderly subjects

    International Nuclear Information System (INIS)

    Deverdun, Jérémy; Menjot de Champfleur, Sophie; Cabello-Aguilar, Simon; Maury, Florence; Molino, François; Charif, Mahmoud; Leboucq, Nicolas; Ayrignac, Xavier; Labauge, Pierre

    2014-01-01

    Background and Purpose: The etiologic diagnosis of parkinsonian syndromes is of particular importance when considering syndromes of vascular or degenerative origin. The purpose of this study is to find differences in the white-matter architecture between those two groups in elderly patients. Materials and Methods: Thirty-five patients were prospectively included (multiple-system atrophy, n = 5; Parkinson's disease, n = 15; progressive supranuclear palsy, n = 9; vascular parkinsonism, n = 6), with a mean age of 76 years. Patients with multiple-system atrophy, progressive supranuclear palsy and Parkinson's disease were grouped as having parkinsonian syndromes of degenerative origin. Brain MRIs included diffusion tensor imaging. Fractional anisotropy and mean-diffusivity maps were spatially normalized, and group analyses between parkinsonian syndromes of degenerative origin and vascular parkinsonism were performed using a voxel-based approach. Results: Statistical parametric-mapping analysis of diffusion tensor imaging data showed decreased fractional anisotropy value in internal capsules bilaterally in patients with vascular parkinsonism compared to parkinsonian syndromes of degenerative origin (p = 0.001) and showed a lower mean diffusivity in the white matter of the left superior parietal lobule (p = 0.01). Fractional anisotropy values were found decreased in the middle cerebellar peduncles in multiple-system atrophy compared to Parkinson's disease and progressive supranuclear palsy. The mean diffusivity was increased in those regions for these subgroups. Conclusion: Clinically defined vascular parkinsonism was associated with decreased fractional anisotropy in the deep white matter (internal capsules) compared to parkinsonian syndromes of degenerative origin. These findings are consistent with previously published neuropathological data

  5. Whole-brain diffusion-tensor changes in parkinsonian patients with impulse control disorders.

    Science.gov (United States)

    Yoo, Hye Bin; Lee, Jee-Young; Lee, Jae Sung; Kang, Hyejin; Kim, Yu Kyeong; Song, In Chan; Lee, Dong Soo; Jeon, Beom Seok

    2015-01-01

    The aim of this study was to determine the changes in diffusion-tensor images associated with medication-related impulse control disorder (ICD) in Parkinson's disease (PD) patients undergoing chronic dopamine-replacement therapy. Nineteen PD patients, comprising 10 with ICD (PD-ICD) and 9 without ICD (PD-nonICD), and 18 age-matched healthy controls (HCs) with no cognitive or other psychiatric disorders were analyzed. All subjects underwent 3-T magnetic resonance diffusion-tensor imaging. For all PD patients, clinical data on PD duration, antiparkinsonian medication dosages, Unified Parkinson's Disease Rating Scale and Mini-Mental State Examination were collected. Whole-brain voxel-based measures of fractional anisotropy (FA) and mean diffusivity (MD) were analyzed. In comparison with HCs, the PD-nonICD subjects had low FA at the bilateral orbitofrontal areas. While the PD-ICD subjects exhibited no such difference, their FA was significantly elevated at the anterior corpus callosum. Analysis of FA between the two PD groups revealed that FA in the anterior corpus callosum, right internal capsule posterior limbs, right posterior cingulum, and right thalamic radiations were significantly higher (corrected p<0.05) in the PD-ICD than in the PD-nonICD patients. MD did not differ between the PD-ICD and PD-nonICD groups in any brain regions. The PD-ICD patients appear to have relatively preserved white-matter integrity in the regions involved in reward-related behaviors compared to PD-nonICD patients. Further investigation is required to determine whether the difference in FA between PD-ICD and PD-nonICD patients reflects microstructural differences in the pathological progression of PD or is secondary to ICD.

  6. The utility of preoperative diffusion tensor imaging in the surgical management of brainstem cavernous malformations.

    Science.gov (United States)

    Flores, Bruno C; Whittemore, Anthony R; Samson, Duke S; Barnett, Samuel L

    2015-03-01

    Resection of brainstem cavernous malformations (BSCMs) may reduce the risk of stepwise neurological deterioration secondary to hemorrhage, but the morbidity of surgery remains high. Diffusion tensor imaging (DTI) and diffusion tensor tractography (DTT) are neuroimaging techniques that may assist in the complex surgical planning necessary for these lesions. The authors evaluate the utility of preoperative DTI and DTT in the surgical management of BSCMs and their correlation with functional outcome. A retrospective review was conducted to identify patients who underwent resection of a BSCM between 2007 and 2012. All patients had preoperative DTI/DTT studies and a minimum of 6 months of clinical and radiographic follow-up. Five major fiber tracts were evaluated preoperatively using the DTI/DTT protocol: 1) corticospinal tract, 2) medial lemniscus and medial longitudinal fasciculus, 3) inferior cerebellar peduncle, 4) middle cerebellar peduncle, and 5) superior cerebellar peduncle. Scores were applied according to the degree of distortion seen, and the sum of scores was used for analysis. Functional outcomes were measured at hospital admission, discharge, and last clinic visit using modified Rankin Scale (mRS) scores. Eleven patients who underwent resection of a BSCM and preoperative DTI were identified. The mean age at presentation was 49 years, with a male-to-female ratio of 1.75:1. Cranial nerve deficit was the most common presenting symptom (81.8%), followed by cerebellar signs or gait/balance difficulties (54.5%) and hemibody anesthesia (27.2%). The majority of the lesions were located within the pons (54.5%). The mean diameter and estimated volume of lesions were 1.21 cm and 1.93 cm(3), respectively. Using DTI and DTT, 9 patients (82%) were found to have involvement of 2 or more major fiber tracts; the corticospinal tract and medial lemniscus/medial longitudinal fasciculus were the most commonly affected. In 2 patients with BSCMs without pial presentation, DTI

  7. Diffusion and saponification inside porous cellulose triacetate fibers.

    Science.gov (United States)

    Braun, Jennifer L; Kadla, John F

    2005-01-01

    Cellulose triacetate (CTA) fibers were partially hydrolyzed in 0.054 N solutions of NaOH/H(2)O and NaOMe/MeOH. The surface concentration of acetyl groups was determined using ATR-FTIR. Total acetyl content was determined by the alkaline hydrolysis method. Fiber cross-sections were stained with Congo red in order to examine the interface between reacted and unreacted material; these data were used to estimate the rate constant k and effective diffusivity D(B) for each reagent during the early stages of reaction by means of a volume-based unreacted core model. For NaOH/H(2)O, k = 0.37 L mol(-1) min(-1) and D(B) = 6.2 x 10(-7) cm(2)/sec; for NaOMe/MeOH, k = 4.0 L mol(-1) min(-1) and D(B) = 5.7 x 10(-6) cm(2)/sec. The NaOMe/MeOH reaction has a larger rate constant due to solvent effects and the greater nucleophilicity of MeO(-) as compared to OH(-); the reaction has a larger effective diffusivity because CTA swells more in MeOH than it does in water. Similarities between calculated concentration profiles for each case indicate that the relatively diffuse interface seen in fibers from the NaOMe/MeOH reaction results from factors not considered in the model; shrinkage of stained fiber cross-sections suggests that increased disruption of intermolecular forces may be the cause.

  8. New insights into the developing rabbit brain using diffusion tensor tractography and generalized q-sampling MRI.

    Directory of Open Access Journals (Sweden)

    Seong Yong Lim

    Full Text Available The use of modern neuroimaging methods to characterize the complex anatomy of brain development at different stages reveals an enormous wealth of information in understanding this highly ordered process and provides clues to detect neurological and neurobehavioral disorders that have their origin in early structural and functional cerebral maturation. Non-invasive diffusion tensor magnetic resonance imaging (DTI is able to distinguish cerebral microscopic structures, especially in the white matter regions. However, DTI is unable to resolve the complicated neural structure, i.e., the fiber crossing that is frequently observed during the maturation process. To overcome this limitation, several methods have been proposed. One such method, generalized q-sampling imaging (GQI, can be applied to a variety of datasets, including the single shell, multi-shell or grid sampling schemes that are believed to be able to resolve the complicated crossing fibers. Rabbits have been widely used for neurodevelopment research because they exhibit human-like timing of perinatal brain white matter maturation. Here, we present a longitudinal study using both DTI and GQI to demonstrate the changes in cerebral maturation of in vivo developing rabbit brains over a period of 40 weeks. Fractional anisotropy (FA of DTI and generalized fractional anisotropy (GFA of GQI indices demonstrated that the white matter anisotropy increased with age, with GFA exhibiting an increase in the hippocampus as well. Normalized quantitative anisotropy (NQA of GQI also revealed an increase in the hippocampus, allowing us to observe the changes in gray matter as well. Regional and whole brain DTI tractography also demonstrated refinement in fiber pathway architecture with maturation. We concluded that DTI and GQI results were able to characterize the white matter anisotropy changes, whereas GQI provided further information about the gray matter hippocampus area. This developing rabbit brain

  9. Determination of 13C CSA Tensors: Extension of the Model-independent Approach to an RNA Kissing Complex Undergoing Anisotropic Rotational Diffusion in Solution

    International Nuclear Information System (INIS)

    Ravindranathan, Sapna; Kim, Chul-Hyun; Bodenhausen, Geoffrey

    2005-01-01

    Chemical shift anisotropy (CSA) tensor parameters have been determined for the protonated carbons of the purine bases in an RNA kissing complex in solution by extending the model-independent approach [Fushman, D., Cowburn, D. (1998) J. Am. Chem. Soc. 120, 7109-7110]. A strategy for determining CSA tensor parameters of heteronuclei in isolated X-H two-spin systems (X = 13 C or 15 N) in molecules undergoing anisotropic rotational diffusion is presented. The original method relies on the fact that the ratio κ 2 =R 2 auto /R 2 cross of the transverse auto- and cross-correlated relaxation rates involving the X CSA and the X-H dipolar interaction is independent of parameters related to molecular motion, provided rotational diffusion is isotropic. However, if the overall motion is anisotropic κ 2 depends on the anisotropy D parallel /D -perpendicular of rotational diffusion. In this paper, the field dependence of both κ 2 and its longitudinal counterpart κ 1 =R 1 auto /R 1 cross are determined. For anisotropic rotational diffusion, our calculations show that the average κ av = 1/2 (κ 1 +κ 2 ), of the ratios is largely independent of the anisotropy parameter D parallel /D -perpendicular . The field dependence of the average ratio κ av may thus be utilized to determine CSA tensor parameters by a generalized model-independent approach in the case of molecules with an overall motion described by an axially symmetric rotational diffusion tensor

  10. Fiber architecture in remodeled myocardium revealed with a quantitative diffusion CMR tractography framework and histological validation.

    Science.gov (United States)

    Mekkaoui, Choukri; Huang, Shuning; Chen, Howard H; Dai, Guangping; Reese, Timothy G; Kostis, William J; Thiagalingam, Aravinda; Maurovich-Horvat, Pal; Ruskin, Jeremy N; Hoffmann, Udo; Jackowski, Marcel P; Sosnovik, David E

    2012-10-12

    The study of myofiber reorganization in the remote zone after myocardial infarction has been performed in 2D. Microstructural reorganization in remodeled hearts, however, can only be fully appreciated by considering myofibers as continuous 3D entities. The aim of this study was therefore to develop a technique for quantitative 3D diffusion CMR tractography of the heart, and to apply this method to quantify fiber architecture in the remote zone of remodeled hearts. Diffusion Tensor CMR of normal human, sheep, and rat hearts, as well as infarcted sheep hearts was performed ex vivo. Fiber tracts were generated with a fourth-order Runge-Kutta integration technique and classified statistically by the median, mean, maximum, or minimum helix angle (HA) along the tract. An index of tract coherence was derived from the relationship between these HA statistics. Histological validation was performed using phase-contrast microscopy. In normal hearts, the subendocardial and subepicardial myofibers had a positive and negative HA, respectively, forming a symmetric distribution around the midmyocardium. However, in the remote zone of the infarcted hearts, a significant positive shift in HA was observed. The ratio between negative and positive HA variance was reduced from 0.96 ± 0.16 in normal hearts to 0.22 ± 0.08 in the remote zone of the remodeled hearts (p layers of the myocardium. Tractography-based quantification, performed here for the first time in remodeled hearts, may provide a framework for assessing regional changes in the left ventricle following infarction.

  11. Segmentation of the Canine Corpus Callosum using Diffusion Tensor Imaging Tractography

    Science.gov (United States)

    Pierce, T.T.; Calabrese, E.; White, L.E.; Chen, S.D.; Platt, S.R.; Provenzale, J.M.

    2014-01-01

    Background We set out to determine functional white matter (WM) connections passing through the canine corpus callosum useful for subsequent studies of canine brains that serve as models for human WM pathway disease. Based on prior studies, we anticipated that the anterior corpus callosum would send projections to the anterior cerebral cortex while progressively posterior segments would send projections to more posterior cortex. Methods A post mortem canine brain was imaged using a 7T MRI producing 100 micron isotropic resolution DTI analyzed by tractography. Using ROIs within cortical locations, which were confirmed by a Nissl stain that identified distinct cortical architecture, we successfully identified 6 important WM pathways. We also compared fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity (RD), and axial diffusivity (AD) in tracts passing through the genu and splenium. Results Callosal fibers were organized based upon cortical destination, i.e. fibers from the genu project to the frontal cortex. Histologic results identified the motor cortex based on cytoarchitectonic criteria that allowed placement of ROIs to discriminate between frontal and parietal lobes. We also identified cytoarchitecture typical of the orbital frontal, anterior frontal, and occipital regions and placed ROIs accordingly. FA, ADC, RD and AD values were all higher in posterior corpus callosum fiber tracts. Conclusions Using 6 cortical ROIs, we identified 6 major white matter tracts that reflect major functional divisions of the cerebral hemispheres and we derived quantitative values that can be used for study of canine models of human WM pathological states. PMID:24370161

  12. Moisture diffusivity in structure of random fractal fiber bed

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Fanglong, E-mail: zhufanglong_168@163.com [College of Textile, Zhongyuan University of Technology, Zhengzhou City (China); The Chinese People' s Armed Police Forces Academy, Langfan City (China); Zhou, Yu; Feng, Qianqian [College of Textile, Zhongyuan University of Technology, Zhengzhou City (China); Xia, Dehong [School of Mechanical Engineering, University of Science and Technology, Beijing (China)

    2013-11-08

    A theoretical expression related to effective moisture diffusivity to random fiber bed is derived by using fractal theory and considering both parallel and perpendicular channels to diffusion flow direction. In this Letter, macroporous structure of hydrophobic nonwoven material is investigated, and Knudsen diffusion and surface diffusion are neglected. The effective moisture diffusivity predicted by the present fractal model are compared with water vapor transfer rate (WVTR) experiment data and calculated values obtained from other theoretical models. This verifies the validity of the present fractal diffusivity of fibrous structural beds.

  13. Structural changes of central white matter tracts in Kennedy's disease - a diffusion tensor imaging and voxel-based morphometry study.

    Science.gov (United States)

    Pieper, C C; Konrad, C; Sommer, J; Teismann, I; Schiffbauer, H

    2013-05-01

    Spinobulbar muscular atrophy [Kennedy's disease (KD)] is a rare X-linked neurodegenerative disorder of mainly spinal and bulbar motoneurons. Recent studies suggest a multisystem character of this disease. The aim of this study was to identify and characterize structural changes of gray (GM) and white matter (WM) in the central nervous system. Whole-brain-based voxel-based morphometry (VBM) and diffusion tensor imaging (DTI) analyses were applied to MRI data of eight genetically proven patients with KD and compared with 16 healthy age-matched controls. Diffusion tensor imaging analysis showed not only decreased fractional anisotropy (FA) values in the brainstem, but also widespread changes in central WM tracts, whereas VBM analysis of the WM showed alterations primarily in the brainstem and cerebellum. There were no changes in GM volume. The FA value decrease in the brainstem correlated with the disease duration. Diffusion tensor imaging analysis revealed subtle changes of central WM tract integrity, while GM and WM volume remained unaffected. In our patient sample, KD had more extended effects than previously reported. These changes could either be attributed primarily to neurodegeneration or reflect secondary plastic changes due to atrophy of lower motor neurons and reorganization of cortical structures. © 2012 John Wiley & Sons A/S.

  14. Comparison between cerebral ischemia disease and multiple sclerosis by using MR diffusion tensor imaging

    International Nuclear Information System (INIS)

    Lou Xin; Cai Youquan; Ma Lin; Cai Jianming

    2007-01-01

    Objective: To assess the value of MR diffusion tensor imaging (DTI) in the differentiation between the patients with cerebral ischemia disease and multiple sclerosis. Methods: MR diffusion tensor imaging was performed in thirty-two patients with internal carotid artery stenosis ≥70% and eighteen patients with clinical diagnosed multiple sclerosis. Fractional anisotropy (FA) value of the germ, splenium, body of the corpus callosum, and the white matter of the frontal and occipital lobe were measured respectively, and independent-sample t-test statistical analysis was performed. Results: The FA value was decreased obviously in the anterior and posterior body and splenium of the corpus callosumin the MS patients compared with the ICA severe stenosis patients (0.67 ± 0.12 vs. 0.75 ± 0.05, t=3.443, P 0.05; 0.34 ± 0.08 vs. 0.34 ± 0.05, t=0.137, P> 0.05; 0.29 ± 0.06 vs. 0.40 ± 0.06, t=5.449, P>0.05). Conclusion: DTI can noninvasive detect the potential disorder of corpus callosum in vivo, thus providing useful information to differentiate the cerebral ischemia disease from multiple sclerosis. (authors)

  15. Preoperative Identification of Facial Nerve in Vestibular Schwannomas Surgery Using Diffusion Tensor Tractography

    OpenAIRE

    Choi, Kyung-Sik; Kim, Min-Su; Kwon, Hyeok-Gyu; Jang, Sung-Ho; Kim, Oh-Lyong

    2014-01-01

    Objective Facial nerve palsy is a common complication of treatment for vestibular schwannoma (VS), so preserving facial nerve function is important. The preoperative visualization of the course of facial nerve in relation to VS could help prevent injury to the nerve during the surgery. In this study, we evaluate the accuracy of diffusion tensor tractography (DTT) for preoperative identification of facial nerve. Methods We prospectively collected data from 11 patients with VS, who underwent pr...

  16. Experimental evaluation of electrical conductivity imaging of anisotropic brain tissues using a combination of diffusion tensor imaging and magnetic resonance electrical impedance tomography

    Energy Technology Data Exchange (ETDEWEB)

    Sajib, Saurav Z. K.; Jeong, Woo Chul; Oh, Tong In; Kim, Hyung Joong, E-mail: bmekim@khu.ac.kr, E-mail: ejwoo@khu.ac.kr; Woo, Eung Je, E-mail: bmekim@khu.ac.kr, E-mail: ejwoo@khu.ac.kr [Department of Biomedical Engineering, Kyung Hee University, Seoul 02447 (Korea, Republic of); Kyung, Eun Jung [Department of Pharmacology, Chung-Ang University, Seoul 06974 (Korea, Republic of); Kim, Hyun Bum [Department of East-West Medical Science, Kyung Hee University, Yongin 17104 (Korea, Republic of); Kwon, Oh In [Department of Mathematics, Konkuk University, Seoul 05029 (Korea, Republic of)

    2016-06-15

    Anisotropy of biological tissues is a low-frequency phenomenon that is associated with the function and structure of cell membranes. Imaging of anisotropic conductivity has potential for the analysis of interactions between electromagnetic fields and biological systems, such as the prediction of current pathways in electrical stimulation therapy. To improve application to the clinical environment, precise approaches are required to understand the exact responses inside the human body subjected to the stimulated currents. In this study, we experimentally evaluate the anisotropic conductivity tensor distribution of canine brain tissues, using a recently developed diffusion tensor-magnetic resonance electrical impedance tomography method. At low frequency, electrical conductivity of the biological tissues can be expressed as a product of the mobility and concentration of ions in the extracellular space. From diffusion tensor images of the brain, we can obtain directional information on diffusive movements of water molecules, which correspond to the mobility of ions. The position dependent scale factor, which provides information on ion concentration, was successfully calculated from the magnetic flux density, to obtain the equivalent conductivity tensor. By combining the information from both techniques, we can finally reconstruct the anisotropic conductivity tensor images of brain tissues. The reconstructed conductivity images better demonstrate the enhanced signal intensity in strongly anisotropic brain regions, compared with those resulting from previous methods using a global scale factor.

  17. Visualization of Fiber Structure in the Left and Right Ventricle of a Human Heart

    International Nuclear Information System (INIS)

    Rohmer, Damien; Sitek, Arkadiusz; Gullberg, Grant T.

    2006-01-01

    The human heart is composed of a helical network of muscle fibers. Anisotropic least squares filtering followed by fiber tracking techniques were applied to Diffusion Tensor Magnetic Resonance Imaging(DTMRI) data of the excised human heart. The fiber configuration was visualized by using thin tubes to increase 3-dimensional visual perception of the complex structure. All visualizations were performed using the high-quality ray-tracing software POV-Ray. The fibers are shown within the left and right ventricles. Both ventricles exhibit similar fiber architecture and some bundles of fibers are shown linking right and left ventricles on the posterior region of the heart

  18. Diffusion tensor imaging in spinal cord injury

    International Nuclear Information System (INIS)

    Kamble, Ravindra B; Venkataramana, Neelam K; Naik, Arun L; Rao, Shailesh V

    2011-01-01

    To assess the feasibility of spinal tractography in patients of spinal cord injury vs a control group and to compare fractional anisotropy (FA) values between the groups. Diffusion tensor imaging (DTI) was performed in the spinal cord of 29 patients (18 patients and 11 controls). DTI was done in the cervical region if the cord injury was at the dorsal or lumbar region and in the conus region if cord injury was in the cervical or dorsal region. FA was calculated for the patients and the controls and the values were compared. The mean FA value was 0.550±0.09 in the control group and 0.367±0.14 in the patients; this difference was statistically significant (P=0.001). Spinal tractography is a feasible technique to assess the extent of spinal cord injury by FA, which is reduced in patients of spinal cord injury, suggesting possible Wallerian degeneration. In future, this technique may become a useful tool for assessing cord injury patients after stem cell therapy, with improvement in FA values indicating axonal regeneration

  19. 人脑神经心理功能的DTI研究%Diffusion tensor imaging research on some neuropsychological function of human brain

    Institute of Scientific and Technical Information of China (English)

    何冠勇; 刘远健

    2016-01-01

    目的:探讨MR弥散张量成像( DTI)技术在记忆、学习、语言、音乐及思维活动相关脑区白质纤维的研究进展。方法在 Medline 和 Embase 数据库,以“diffusion tensor imaging”与“memory”、“study”、“language”、“music”、“cognition”等为关键词,检索2015年6月之前发表的MR DTI技术研究有关心理神经功能的文章进行分析总结。对检索到100余篇文献进行筛选,以近5年发表在较权威期刊者优先纳入,主要文献32篇。结果人脑白质纤维通过记忆、学习、语言、音乐及认知活动可发生重塑性改变。结论 MR DTI技术作为一种能无创显示活体内脑白质纤维变化的技术,可广泛应用于各种认知训练及神经心理功能研究。%Objective To explore the progress of neuropsychological profile on memory, study, language, music, and cognition with diffusion tensor imaging(DTI). Methods A computer-based online database of Medline and Embase were undertaken to identify all articles about neuropsychological activities and diffusion tensor imaging with the key words of "memory, study, language, music, and cognition"published from January 2004 to June 2015. The search involved in more than 100 articles, as the key 32 of them were issued on authority magazines recently. Results The white matter fiber of human brain can be changed and remodeled through memory, learning, language, music and cognitive activity. Conclusions As a kind of technology to display the changing white matter construction of brain in vivo, magnetic resonance DTI are widely used in research on a variety of neuropsychological function as well as cognitive training.

  20. Simultaneous Multislice Echo Planar Imaging With Blipped Controlled Aliasing in Parallel Imaging Results in Higher Acceleration: A Promising Technique for Accelerated Diffusion Tensor Imaging of Skeletal Muscle.

    Science.gov (United States)

    Filli, Lukas; Piccirelli, Marco; Kenkel, David; Guggenberger, Roman; Andreisek, Gustav; Beck, Thomas; Runge, Val M; Boss, Andreas

    2015-07-01

    The aim of this study was to investigate the feasibility of accelerated diffusion tensor imaging (DTI) of skeletal muscle using echo planar imaging (EPI) applying simultaneous multislice excitation with a blipped controlled aliasing in parallel imaging results in higher acceleration unaliasing technique. After federal ethics board approval, the lower leg muscles of 8 healthy volunteers (mean [SD] age, 29.4 [2.9] years) were examined in a clinical 3-T magnetic resonance scanner using a 15-channel knee coil. The EPI was performed at a b value of 500 s/mm2 without slice acceleration (conventional DTI) as well as with 2-fold and 3-fold acceleration. Fractional anisotropy (FA) and mean diffusivity (MD) were measured in all 3 acquisitions. Fiber tracking performance was compared between the acquisitions regarding the number of tracks, average track length, and anatomical precision using multivariate analysis of variance and Mann-Whitney U tests. Acquisition time was 7:24 minutes for conventional DTI, 3:53 minutes for 2-fold acceleration, and 2:38 minutes for 3-fold acceleration. Overall FA and MD values ranged from 0.220 to 0.378 and 1.595 to 1.829 mm2/s, respectively. Two-fold acceleration yielded similar FA and MD values (P ≥ 0.901) and similar fiber tracking performance compared with conventional DTI. Three-fold acceleration resulted in comparable MD (P = 0.199) but higher FA values (P = 0.006) and significantly impaired fiber tracking in the soleus and tibialis anterior muscles (number of tracks, P DTI of skeletal muscle with similar image quality and quantification accuracy of diffusion parameters. This may increase the clinical applicability of muscle anisotropy measurements.

  1. Combining Diffusion Tensor Metrics and DSC Perfusion Imaging: Can It Improve the Diagnostic Accuracy in Differentiating Tumefactive Demyelination from High-Grade Glioma?

    Science.gov (United States)

    Hiremath, S B; Muraleedharan, A; Kumar, S; Nagesh, C; Kesavadas, C; Abraham, M; Kapilamoorthy, T R; Thomas, B

    2017-04-01

    Tumefactive demyelinating lesions with atypical features can mimic high-grade gliomas on conventional imaging sequences. The aim of this study was to assess the role of conventional imaging, DTI metrics ( p:q tensor decomposition), and DSC perfusion in differentiating tumefactive demyelinating lesions and high-grade gliomas. Fourteen patients with tumefactive demyelinating lesions and 21 patients with high-grade gliomas underwent brain MR imaging with conventional, DTI, and DSC perfusion imaging. Imaging sequences were assessed for differentiation of the lesions. DTI metrics in the enhancing areas and perilesional hyperintensity were obtained by ROI analysis, and the relative CBV values in enhancing areas were calculated on DSC perfusion imaging. Conventional imaging sequences had a sensitivity of 80.9% and specificity of 57.1% in differentiating high-grade gliomas ( P = .049) from tumefactive demyelinating lesions. DTI metrics ( p : q tensor decomposition) and DSC perfusion demonstrated a statistically significant difference in the mean values of ADC, the isotropic component of the diffusion tensor, the anisotropic component of the diffusion tensor, the total magnitude of the diffusion tensor, and rCBV among enhancing portions in tumefactive demyelinating lesions and high-grade gliomas ( P ≤ .02), with the highest specificity for ADC, the anisotropic component of the diffusion tensor, and relative CBV (92.9%). Mean fractional anisotropy values showed no significant statistical difference between tumefactive demyelinating lesions and high-grade gliomas. The combination of DTI and DSC parameters improved the diagnostic accuracy (area under the curve = 0.901). Addition of a heterogeneous enhancement pattern to DTI and DSC parameters improved it further (area under the curve = 0.966). The sensitivity increased from 71.4% to 85.7% after the addition of the enhancement pattern. DTI and DSC perfusion add profoundly to conventional imaging in differentiating tumefactive

  2. Assessment of tissue heterogeneity using diffusion tensor and diffusion kurtosis imaging for grading gliomas

    Energy Technology Data Exchange (ETDEWEB)

    Raja, Rajikha; Sinha, Neelam [International Institute of Information Technology-Bangalore, Bangalore (India); Saini, Jitender; Mahadevan, Anita; Rao, K.V.L. Narasinga; Swaminathan, Aarthi [National Institute of Mental Health and Neurosciences, Bangalore (India)

    2016-12-15

    In this work, we aim to assess the significance of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) parameters in grading gliomas. Retrospective studies were performed on 53 subjects with gliomas belonging to WHO grade II (n = 19), grade III (n = 20) and grade IV (n = 14). Expert marked regions of interest (ROIs) covering the tumour on T2-weighted images. Statistical texture measures such as entropy and busyness calculated over ROIs on diffusion parametric maps were used to assess the tumour heterogeneity. Additionally, we propose a volume heterogeneity index derived from cross correlation (CC) analysis as a tool for grading gliomas. The texture measures were compared between grades by performing the Mann-Whitney test followed by receiver operating characteristic (ROC) analysis for evaluating diagnostic accuracy. Entropy, busyness and volume heterogeneity index for all diffusion parameters except fractional anisotropy and anisotropy of kurtosis showed significant differences between grades. The Mann-Whitney test on mean diffusivity (MD), among DTI parameters, resulted in the highest discriminability with values of P = 0.029 (0.0421) for grade II vs. III and P = 0.0312 (0.0415) for III vs. IV for entropy (busyness). In DKI, mean kurtosis (MK) showed the highest discriminability, P = 0.018 (0.038) for grade II vs. III and P = 0.022 (0.04) for III vs. IV for entropy (busyness). Results of CC analysis illustrate the existence of homogeneity in volume (uniformity across slices) for lower grades, as compared to higher grades. Hypothesis testing performed on volume heterogeneity index showed P values of 0.0002 (0.0001) and 0.0003 (0.0003) between grades II vs. III and III vs. IV, respectively, for MD (MK). In summary, the studies demonstrated great potential towards automating grading gliomas by employing tumour heterogeneity measures on DTI and DKI parameters. (orig.)

  3. Assessment of tissue heterogeneity using diffusion tensor and diffusion kurtosis imaging for grading gliomas

    International Nuclear Information System (INIS)

    Raja, Rajikha; Sinha, Neelam; Saini, Jitender; Mahadevan, Anita; Rao, K.V.L. Narasinga; Swaminathan, Aarthi

    2016-01-01

    In this work, we aim to assess the significance of diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) parameters in grading gliomas. Retrospective studies were performed on 53 subjects with gliomas belonging to WHO grade II (n = 19), grade III (n = 20) and grade IV (n = 14). Expert marked regions of interest (ROIs) covering the tumour on T2-weighted images. Statistical texture measures such as entropy and busyness calculated over ROIs on diffusion parametric maps were used to assess the tumour heterogeneity. Additionally, we propose a volume heterogeneity index derived from cross correlation (CC) analysis as a tool for grading gliomas. The texture measures were compared between grades by performing the Mann-Whitney test followed by receiver operating characteristic (ROC) analysis for evaluating diagnostic accuracy. Entropy, busyness and volume heterogeneity index for all diffusion parameters except fractional anisotropy and anisotropy of kurtosis showed significant differences between grades. The Mann-Whitney test on mean diffusivity (MD), among DTI parameters, resulted in the highest discriminability with values of P = 0.029 (0.0421) for grade II vs. III and P = 0.0312 (0.0415) for III vs. IV for entropy (busyness). In DKI, mean kurtosis (MK) showed the highest discriminability, P = 0.018 (0.038) for grade II vs. III and P = 0.022 (0.04) for III vs. IV for entropy (busyness). Results of CC analysis illustrate the existence of homogeneity in volume (uniformity across slices) for lower grades, as compared to higher grades. Hypothesis testing performed on volume heterogeneity index showed P values of 0.0002 (0.0001) and 0.0003 (0.0003) between grades II vs. III and III vs. IV, respectively, for MD (MK). In summary, the studies demonstrated great potential towards automating grading gliomas by employing tumour heterogeneity measures on DTI and DKI parameters. (orig.)

  4. Tract-Specific Analyses of Diffusion Tensor Imaging Show Widespread White Matter Compromise in Autism Spectrum Disorder

    Science.gov (United States)

    Shukla, Dinesh K.; Keehn, Brandon; Muller, Ralph-Axel

    2011-01-01

    Background: Previous diffusion tensor imaging (DTI) studies have shown white matter compromise in children and adults with autism spectrum disorder (ASD), which may relate to reduced connectivity and impaired function of distributed networks. However, tract-specific evidence remains limited in ASD. We applied tract-based spatial statistics (TBSS)…

  5. Multi-Shell Hybrid Diffusion Imaging (HYDI) at 7 Tesla in TgF344-AD Transgenic Alzheimer Rats

    OpenAIRE

    Daianu, Madelaine; Jacobs, Russell E.; Weitz, Tara M.; Town, Terrence C.; Thompson, Paul M.

    2015-01-01

    Diffusion weighted imaging (DWI) is widely used to study microstructural characteristics of the brain. Diffusion tensor imaging (DTI) and high-angular resolution imaging (HARDI) are frequently used in radiology and neuroscience research but can be limited in describing the signal behavior in composite nerve fiber structures. Here, we developed and assessed the benefit of a comprehensive diffusion encoding scheme, known as hybrid diffusion imaging (HYDI), composed of 300 DWI volumes acquired a...

  6. Particle-level simulations of flocculation in a fiber suspension flowing through a diffuser

    Directory of Open Access Journals (Sweden)

    Andrić Jelena S.

    2017-01-01

    Full Text Available We investigate flocculation in dilute suspensions of rigid, straight fibers in a decelerating flow field of a diffuser. We carry out numerical studies using a particle-level simulation technique that takes into account the fiber inertia and the non-creeping fiber-flow interactions. The fluid flow is governed by the Reynolds-averaged Navier-Stokes equations with the standard k-omega eddy-viscosity turbulence model. A one-way coupling between the fibers and the flow is considered with a stochastic model for the fiber dispersion due to turbulence. The fibers interact through short-range attractive forces that cause them to aggregate into flocs when fiber-fiber collisions occur. We show that ballistic deflection of fibers greatly increases the flocculation in the diffuser. The inlet fiber kinematics and the fiber inertia are the main parameters that affect fiber flocculation in the prediffuser region.

  7. Diffusion tensor imaging in children and adolescents with tuberous sclerosis

    Energy Technology Data Exchange (ETDEWEB)

    Karadag, Demet [Institute of Diagnostic and Interventional Radiology, Friedrich Schiller University, Department of Paediatric Radiology, Jena (Germany); Kirikkale Yuksek Ihtisas Hospital, Department of Radiology, Kirirkale (Turkey); Mentzel, Hans-J.; Loebel, Ulrike; Reichenbach, Juergen R.; Kaiser, Werner A. [Institute of Diagnostic and Interventional Radiology, Friedrich Schiller University, Department of Paediatric Radiology, Jena (Germany); Guellmar, Daniel [Institute of Diagnostic and Interventional Radiology, Friedrich Schiller University, Department of Paediatric Radiology, Jena (Germany); Friedrich Schiller University, Biomagnetic Centre, Clinic of Neurology, Jena (Germany); Rating, Tina; Brandl, Ulrich [Friedrich Schiller University, Department of Paediatric Neurology, Jena (Germany)

    2005-10-01

    Tuberous sclerosis (TS) is characterised by benign hamartomatous lesions in many organs. Diffusion tensor imaging (DTI) can detect microstructural changes in pathological processes. To determine apparent diffusion coefficient (ADC) and fractional anisotropy (FA) maps in children with TS and to investigate the diffusion properties in cortical tubers, white-matter lesions, perilesional white matter, and contralateral normal-appearing white matter, and to compare the results with ADC and FA maps of normal age- and sex-matched volunteers. Seven children and adolescents (age range 2-20 years) suffering from TS were included. MRI was performed on a 1.5-T scanner using a transmit/receive coil with T1-W and T2-W spin-echo and FLAIR sequences. DT images were acquired by using a single-shot echo-planar pulse sequence. Diffusion gradients were applied in six different directions with a b value of 1,000 s/mm{sup 2}. ADC was higher in cortical tubers than in the corresponding cortical location of controls. ADC values were higher and FA values were lower in white-matter lesions and perilesional white matter than in both the contralateral normal-appearing white matter of patients and in controls. There were no significant differences for both ADC and FA values in the normal-appearing white matter of patients with TS compared to controls. DTI provides important information about cortical tubers, white-matter abnormalities, and perilesional white matter in patients with TS. (orig.)

  8. Quantitative evaluation of normal lumbosacral plexus nerve by using diffusion tensor imaging

    International Nuclear Information System (INIS)

    Shi Yin; Wang Chuanbing; Liu Wei; Zong Min; Sa Rina; Shi Haibin; Wang Dehang

    2014-01-01

    Objective: To observe the lumbosacral plexus nerves by diffusion tensor tractography (DTT) and quantitatively evaluate them by using diffusion tensor imaging (DTI) in healthy volunteers. Methods: A total of 60 healthy volunteers (30 males and 30 females) underwent DTI scanning. Mean FA values of the lumbosacral plexus nerves (both sides of lumbar roots L3 to S1, proximal and distal to the lumbar foraminal zone) were quantified. Differences among various segments of lumbar nerve roots were compared with ANOVA test and SNK test. Differences between two sides of the lumbar nerve roots at the same lumbar segment were compared with paired-samples t test. Differences between the proximal and the distal nerve to the the lumbar foraminal zone at the same lumbar segment were compared with paired-samples t test. The lumbosacral plexus nerve was visualized with tractography. Results: (1) The lumbosacral plexus nerve was clearly visualized with tractography. (2) Mean FA values of the lumbar nerve roots L3 to S1 were as followings: proximal to the left lumbar foraminal zone 0.202 ± 0.021, 0.201 ± 0.026, 0.201 ± 0.027, 0.191 ±0.016, distal to the left lumbar foraminal zone 0.222 ± 0.034, 0.250 ± 0.028, 0.203 ± 0.026, 0.183 ± 0.020, proximal to the right lumbar foraminal zone 0.200 ± 0.023, 0.202 ± 0.023, 0.205 ± 0.027, 0.191 ± 0.017, distal to the right lumbar foraminal zone 0.225 ± 0.032, 0.247 ± 0.027, 0.205 ± 0.033, 0.183 ± 0.021. Mean FA values were significantly different between the proximal nerve to the distal nerve in lumbar nerve roots L3, L4, S1 (t=-9.114-2.366, P<0.05), but not significantly different in L5 (P>0.05). Differences were not found between the right and left side nerves at the same lumbar segment (P>0.05). (3) The whole length of the lumbar roots nerve L3 to S1 can be visualized clearly by using DTT. Conclusions: Diffusion tensor imaging and tractography can show and provide quantitative information of human lumbosacral plexus nerves. DTI

  9. Longitudinal diffusion tensor imaging in amyotrophic lateral sclerosis

    Directory of Open Access Journals (Sweden)

    Keil Carsten

    2012-11-01

    Full Text Available Abstract Background Amyotrophic lateral sclerosis (ALS is a fatal neurodegenerative disorder, caused by progressive loss of motor neurons. Changes are widespread in the subcortical white matter in ALS. Diffusion tensor imaging (DTI detects pathological changes in white matter fibres in vivo, based on alterations in the degree (diffusivity, ADC and directedness (fractional anisotropy, FA of proton movement. Methods 24 patients with ALS and 24 age-matched controls received 1.5T DTI. FA and ADC were analyzed using statistical parametric mapping. In 15 of the 24 ALS patients, a second DTI was obtained after 6 months. Results Decreased FA in the corticospinal tract (CST and frontal areas confirm existing results. With a direct comparison of baseline and follow-up dataset, the progression of upper motor neuron degeneration, reflected in FA decrease, could be captured along the CST and in frontal areas. The involvement of cerebellum in the pathology of ALS, as suspected from functional MRI studies, could be confirmed by a reduced FA (culmen, declive. These structural changes correlated well with disease duration, ALSFRS-R, and physical and executive functions. Conclusion DTI detects changes that are regarded as prominent features of ALS and thus, shows promise in its function as a biomarker. Using the technique herein, we could demonstrate DTI changes at follow-up which correlated well with clinical progression.

  10. Asynchrony of the early maturation of white matter bundles in healthy infants: Quantitative landmarks revealed noninvasively by diffusion tensor imaging

    International Nuclear Information System (INIS)

    Dubois, J.; Perrin, M.; Mangin, J.F.; Cointepas, Y.; Duchesnay, E.; Le Bihan, D.; Hertz-Pannier, L.; Dehaene-Lambertz, G.; Dubois, J.; Dehaene-Lambertz, G.; Perrin, M.; Mangin, J.F.; Cointepas, Y.; Duchesnay, E.; Le Bihan, D.; Hertz-Pannier, L.

    2008-01-01

    Normal cognitive development in infants follows a well-known temporal sequence, which is assumed to be correlated with the structural maturation of underlying functional networks. Postmortem studies and, more recently, structural MR imaging studies have described qualitatively the heterogeneous spatio-temporal progression of white matter myelination. However, in vivo quantification of the maturation phases of fiber bundles is still lacking. We used noninvasive diffusion tensor MR imaging and tractography in twenty-three 1-4-month-old healthy infants to quantify the early maturation of the main cerebral fascicles. A specific maturation model, based on the respective roles of different maturational processes on the diffusion phenomena, was designed to highlight asynchronous maturation across bundles by evaluating the time-course of mean diffusivity and anisotropy changes over the considered developmental period. Using an original approach, a progression of maturation in four relative stages was determined in each tract by estimating the maturation state and speed, from the diffusion indices over the infants group compared with an adults group on one hand, and in each tract compared with the average over bundles on the other hand. Results were coherent with, and extended previous findings in 8 of 11 bundles, showing the anterior limb of the internal capsule and cingulum as the most immature, followed by the optic radiations, arcuate and inferior longitudinal fascicles, then the spino-thalamic tract and fornix, and finally the cortico-spinal tract as the most mature bundle. Thus, this approach provides new quantitative landmarks for further noninvasive research on brain-behavior relationships during normal and abnormal development. (authors)

  11. Fiber architecture in remodeled myocardium revealed with a quantitative diffusion CMR tractography framework and histological validation

    Directory of Open Access Journals (Sweden)

    Mekkaoui Choukri

    2012-10-01

    Full Text Available Abstract Background The study of myofiber reorganization in the remote zone after myocardial infarction has been performed in 2D. Microstructural reorganization in remodeled hearts, however, can only be fully appreciated by considering myofibers as continuous 3D entities. The aim of this study was therefore to develop a technique for quantitative 3D diffusion CMR tractography of the heart, and to apply this method to quantify fiber architecture in the remote zone of remodeled hearts. Methods Diffusion Tensor CMR of normal human, sheep, and rat hearts, as well as infarcted sheep hearts was performed ex vivo. Fiber tracts were generated with a fourth-order Runge-Kutta integration technique and classified statistically by the median, mean, maximum, or minimum helix angle (HA along the tract. An index of tract coherence was derived from the relationship between these HA statistics. Histological validation was performed using phase-contrast microscopy. Results In normal hearts, the subendocardial and subepicardial myofibers had a positive and negative HA, respectively, forming a symmetric distribution around the midmyocardium. However, in the remote zone of the infarcted hearts, a significant positive shift in HA was observed. The ratio between negative and positive HA variance was reduced from 0.96 ± 0.16 in normal hearts to 0.22 ± 0.08 in the remote zone of the remodeled hearts (p Conclusions A significant reorganization of the 3D fiber continuum is observed in the remote zone of remodeled hearts. The positive (rightward shift in HA in the remote zone is greatest in the subepicardium, but involves all layers of the myocardium. Tractography-based quantification, performed here for the first time in remodeled hearts, may provide a framework for assessing regional changes in the left ventricle following infarction.

  12. Communication: On the diffusion tensor in macroscopic theory of cavitation

    Science.gov (United States)

    Shneidman, Vitaly A.

    2017-08-01

    The classical description of nucleation of cavities in a stretched fluid relies on a one-dimensional Fokker-Planck equation (FPE) in the space of their sizes r, with the diffusion coefficient D(r) constructed for all r from macroscopic hydrodynamics and thermodynamics, as shown by Zeldovich. When additional variables (e.g., vapor pressure) are required to describe the state of a bubble, a similar approach to construct a diffusion tensor D ^ generally works only in the direct vicinity of the thermodynamic saddle point corresponding to the critical nucleus. It is shown, nevertheless, that "proper" kinetic variables to describe a cavity can be selected, allowing to introduce D ^ in the entire domain of parameters. In this way, for the first time, complete FPE's are constructed for viscous volatile and inertial fluids. In the former case, the FPE with symmetric D ^ is solved numerically. Alternatively, in the case of an inertial fluid, an equivalent Langevin equation is considered; results are compared with analytics. The suggested approach is quite general and can be applied beyond the cavitation problem.

  13. Diffusion tensor imaging of the cortical plate and subplate in very-low-birth-weight infants

    Energy Technology Data Exchange (ETDEWEB)

    Dudink, Jeroen; Govaert, Paul; Zwol, Arjen L. van; Conneman, Nikk; Goudoever, Johannes B. van [Erasmus MC-Sophia Children' s Hospital, Division of Neonatology, Department of Paediatrics, Rotterdam (Netherlands); Buijs, Jan [Maxima Medical Center, Division of Neonatology, Department of Paediatrics, Veldhoven (Netherlands); Lequin, Maarten [Erasmus MC-Sophia Children' s Hospital, Division of Paediatrics, Department of Radiology, Rotterdam, Zuid-holland (Netherlands)

    2010-08-15

    Many intervention studies in preterm infants aim to improve neurodevelopmental outcome, but short-term proxy outcome measurements are lacking. Cortical plate and subplate development could be such a marker. Our aim was to provide normal DTI reference values for the cortical plate and subplate of preterm infants. As part of an ongoing study we analysed diffusion tensor imaging (DTI) images of 19 preterm infants without evidence of injury on conventional MRI, with normal outcome (Bayley-II assessed at age 2), and scanned in the first 4 days of life. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values in the frontal and temporal subplate and cortical plate were measured in single and multiple voxel regions of interest (ROI) placed on predefined regions. Using single-voxel ROIs, statistically significant inverse correlation was found between gestational age (GA) and FA of the frontal (r = -0.5938, P = 0.0058) and temporal (r = -0.4912, P = 0.0327) cortical plate. ADC values had a significant positive correlation with GA in the frontal (r = 0.5427, P = 0.0164) and temporal (r = 0.5540, P = 0.0138) subplate. Diffusion tensor imaging allows in vivo exploration of the evolving cortical plate and subplate. We provide FA and ADC values of the subplate and cortical plate in very-low-birth-weight (VLBW) infants with normal developmental outcome that can be used as reference values. (orig.)

  14. Diffusion tensor imaging of the cortical plate and subplate in very-low-birth-weight infants

    International Nuclear Information System (INIS)

    Dudink, Jeroen; Govaert, Paul; Zwol, Arjen L. van; Conneman, Nikk; Goudoever, Johannes B. van; Buijs, Jan; Lequin, Maarten

    2010-01-01

    Many intervention studies in preterm infants aim to improve neurodevelopmental outcome, but short-term proxy outcome measurements are lacking. Cortical plate and subplate development could be such a marker. Our aim was to provide normal DTI reference values for the cortical plate and subplate of preterm infants. As part of an ongoing study we analysed diffusion tensor imaging (DTI) images of 19 preterm infants without evidence of injury on conventional MRI, with normal outcome (Bayley-II assessed at age 2), and scanned in the first 4 days of life. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values in the frontal and temporal subplate and cortical plate were measured in single and multiple voxel regions of interest (ROI) placed on predefined regions. Using single-voxel ROIs, statistically significant inverse correlation was found between gestational age (GA) and FA of the frontal (r = -0.5938, P = 0.0058) and temporal (r = -0.4912, P = 0.0327) cortical plate. ADC values had a significant positive correlation with GA in the frontal (r = 0.5427, P = 0.0164) and temporal (r = 0.5540, P = 0.0138) subplate. Diffusion tensor imaging allows in vivo exploration of the evolving cortical plate and subplate. We provide FA and ADC values of the subplate and cortical plate in very-low-birth-weight (VLBW) infants with normal developmental outcome that can be used as reference values. (orig.)

  15. UNC-Utah NA-MIC Framework for DTI Fiber Tract Analysis

    Directory of Open Access Journals (Sweden)

    Audrey Rose Verde

    2014-01-01

    Full Text Available Diffusion tensor imaging has become an important modality in the field ofneuroimaging to capture changes in micro-organization and to assess white matterintegrity or development. While there exists a number of tractography toolsets,these usually lack tools for preprocessing or to analyze diffusion properties alongthe fiber tracts. Currently, the field is in critical need of a coherent end-to-endtoolset for performing an along-fiber tract analysis, accessible to non-technicalneuroimaging researchers. The UNC-Utah NA-MIC DTI framework represents acoherent, open source, end-to-end toolset for atlas fiber tract based DTI analysisencompassing DICOM data conversion, quality control, atlas building, fibertractography, fiber parameterization, and statistical analysis of diffusionproperties. Most steps utilize graphical user interfaces (GUI to simplifyinteraction and provide an extensive DTI analysis framework for non-technicalresearchers/investigators. We illustrate the use of our framework on a smallsample, cross sectional neuroimaging study of 8 healthy 1-year-old children fromthe Infant Brain Imaging Study (IBIS Network. In this limited test study, weillustrate the power of our method by quantifying the diffusion properties at 1year of age on the genu and splenium fiber tracts.

  16. Long-term effects of radiation therapy on white matter of the corpus callosum: a diffusion tensor imaging study in children

    Energy Technology Data Exchange (ETDEWEB)

    Makola, Monwabisi [University of Cincinnati, College of Medicine, Cincinnati, OH (United States); Douglas Ris, M. [Texas Children' s Hospital, Department of Pediatrics, Baylor College of Medicine, Houston, TX (United States); Mahone, E.M. [Kennedy Krieger Institute, Department of Neuropsychology, Baltimore, MD (United States); Johns Hopkins University School of Medicine, Department of Psychiatry and Behavioral Sciences, Baltimore, MD (United States); Yeates, Keith Owen [University of Calgary, Department of Psychology, Alberta Children' s Hospital Research Institute, Hotchkiss Brain Institute, Calgary, AB (Canada); Cecil, Kim M. [Imaging Research Center, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Department of Radiology, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Department of Pediatrics, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Neuroscience Graduate Program, Cincinnati, OH (United States); University of Cincinnati College of Medicine, Department of Environmental Health, Cincinnati, OH (United States)

    2017-12-15

    Despite improving survival rates, children are at risk for long-term cognitive and behavioral difficulties following the diagnosis and treatment of a brain tumor. Surgery, chemotherapy and radiation therapy have all been shown to impact the developing brain, especially the white matter. The purpose of this study was to determine the long-term effects of radiation therapy on white matter integrity, as measured by diffusion tensor imaging, in pediatric brain tumor patients 2 years after the end of radiation treatment, while controlling for surgical interventions. We evaluated diffusion tensor imaging performed at two time points: a baseline 3 to 12 months after surgery and a follow-up approximately 2 years later in pediatric brain tumor patients. A region of interest analysis was performed within three regions of the corpus callosum. Diffusion tensor metrics were determined for participants (n=22) who underwent surgical tumor resection and radiation therapy and demographically matched with participants (n=22) who received surgical tumor resection only. Analysis revealed that 2 years after treatment, the radiation treated group exhibited significantly lower fractional anisotropy and significantly higher radial diffusivity within the body of the corpus callosum compared to the group that did not receive radiation. The findings indicate that pediatric brain tumor patients treated with radiation therapy may be at greater risk of experiencing long-term damage to the body of the corpus callosum than those treated with surgery alone. (orig.)

  17. Long-term effects of radiation therapy on white matter of the corpus callosum: a diffusion tensor imaging study in children

    International Nuclear Information System (INIS)

    Makola, Monwabisi; Douglas Ris, M.; Mahone, E.M.; Yeates, Keith Owen; Cecil, Kim M.

    2017-01-01

    Despite improving survival rates, children are at risk for long-term cognitive and behavioral difficulties following the diagnosis and treatment of a brain tumor. Surgery, chemotherapy and radiation therapy have all been shown to impact the developing brain, especially the white matter. The purpose of this study was to determine the long-term effects of radiation therapy on white matter integrity, as measured by diffusion tensor imaging, in pediatric brain tumor patients 2 years after the end of radiation treatment, while controlling for surgical interventions. We evaluated diffusion tensor imaging performed at two time points: a baseline 3 to 12 months after surgery and a follow-up approximately 2 years later in pediatric brain tumor patients. A region of interest analysis was performed within three regions of the corpus callosum. Diffusion tensor metrics were determined for participants (n=22) who underwent surgical tumor resection and radiation therapy and demographically matched with participants (n=22) who received surgical tumor resection only. Analysis revealed that 2 years after treatment, the radiation treated group exhibited significantly lower fractional anisotropy and significantly higher radial diffusivity within the body of the corpus callosum compared to the group that did not receive radiation. The findings indicate that pediatric brain tumor patients treated with radiation therapy may be at greater risk of experiencing long-term damage to the body of the corpus callosum than those treated with surgery alone. (orig.)

  18. A voxel-based morphometry and diffusion tensor imaging analysis of asymptomatic Parkinson's disease-related G2019S LRRK2 mutation carriers.

    Science.gov (United States)

    Thaler, Avner; Artzi, Moran; Mirelman, Anat; Jacob, Yael; Helmich, Rick C; van Nuenen, Bart F L; Gurevich, Tanya; Orr-Urtreger, Avi; Marder, Karen; Bressman, Susan; Bloem, Bastiaan R; Hendler, Talma; Giladi, Nir; Ben Bashat, Dafna

    2014-05-01

    Patients with Parkinson's disease have reduced gray matter volume and fractional anisotropy in both cortical and sub-cortical structures, yet changes in the pre-motor phase of the disease are unknown. A comprehensive imaging study using voxel-based morphometry and diffusion tensor imaging tract-based spatial statistics analysis was performed on 64 Ashkenazi Jewish asymptomatic first degree relatives of patients with Parkinson's disease (30 mutation carriers), who carry the G2019S mutation in the leucine-rich repeat kinase 2 (LRRK2) gene. No between-group differences in gray matter volume could be noted in either whole-brain or volume-of-interest analysis. Diffusion tensor imaging analysis did not identify group differences in white matter areas, and volume-of-interest analysis identified no differences in diffusivity parameters in Parkinson's disease-related structures. G2019S carriers do not manifest changes in gray matter volume or diffusivity parameters in Parkinson's disease-related structures prior to the appearance of motor symptoms. © 2014 International Parkinson and Movement Disorder Society.

  19. Retrospective Correction of Physiological Noise in DTI Using an Extended Tensor Model and Peripheral Measurements

    Science.gov (United States)

    Mohammadi, Siawoosh; Hutton, Chloe; Nagy, Zoltan; Josephs, Oliver; Weiskopf, Nikolaus

    2013-01-01

    Diffusion tensor imaging is widely used in research and clinical applications, but this modality is highly sensitive to artefacts. We developed an easy-to-implement extension of the original diffusion tensor model to account for physiological noise in diffusion tensor imaging using measures of peripheral physiology (pulse and respiration), the so-called extended tensor model. Within the framework of the extended tensor model two types of regressors, which respectively modeled small (linear) and strong (nonlinear) variations in the diffusion signal, were derived from peripheral measures. We tested the performance of four extended tensor models with different physiological noise regressors on nongated and gated diffusion tensor imaging data, and compared it to an established data-driven robust fitting method. In the brainstem and cerebellum the extended tensor models reduced the noise in the tensor-fit by up to 23% in accordance with previous studies on physiological noise. The extended tensor model addresses both large-amplitude outliers and small-amplitude signal-changes. The framework of the extended tensor model also facilitates further investigation into physiological noise in diffusion tensor imaging. The proposed extended tensor model can be readily combined with other artefact correction methods such as robust fitting and eddy current correction. PMID:22936599

  20. Changes in lumbosacral spinal nerve roots on diffusion tensor imaging in spinal stenosis

    OpenAIRE

    Zhong-jun Hou; Yong Huang; Zi-wen Fan; Xin-chun Li; Bing-yi Cao

    2015-01-01

    Lumbosacral degenerative disc disease is a common cause of lower back and leg pain. Conventional T1-weighted imaging (T1WI) and T2-weighted imaging (T2WI) scans are commonly used to image spinal cord degeneration. However, these modalities are unable to image the entire lumbosacral spinal nerve roots. Thus, in the present study, we assessed the potential of diffusion tensor imaging (DTI) for quantitative assessment of compressed lumbosacral spinal nerve roots. Subjects were 20 young healthy v...

  1. Renal water molecular diffusion characteristics in healthy native kidneys: assessment with diffusion tensor MR imaging.

    Directory of Open Access Journals (Sweden)

    Zhenfeng Zheng

    Full Text Available BACKGROUND: To explore the characteristics of diffusion tensor imaging (DTI and magnetic resonance (MR imaging in healthy native kidneys. METHODS: Seventy-three patients without chronic kidney disease underwent DTI-MRI with spin echo-echo planar (SE-EPI sequences accompanied by an array spatial sensitivity encoding technique (ASSET. Cortical and medullary mean, axial and radial diffusivity (MD, AD and RD, fractional anisotropy (FA and primary, secondary and tertiary eigenvalues (λ1, λ2, λ3 were analysed in both kidneys and in different genders. RESULTS: Cortical MD, λ2, λ3, and RD values were higher than corresponding medullary values. The cortical FA value was lower than the medullary FA value. Medullary λ1 and RD values in the left kidney were lower than in the right kidney. Medullary λ2, and λ3 values in women were higher than those in men. Medullary FA values in women were lower than those in men. Medullary FA (r = 0.351, P = 0.002 and λ1 (r = 0.277, P = 0.018 positively correlated with eGFR. Medullary FA (r = -0.25, P = 0.033 negatively correlated with age. CONCLUSIONS: Renal water molecular diffusion differences exist in human kidneys and genders. Age and eGFR correlate with medullary FA and primary eigenvalue.

  2. Test-Retest Reliability of Diffusion Tensor Imaging in Huntington's Disease.

    Science.gov (United States)

    Cole, James H; Farmer, Ruth E; Rees, Elin M; Johnson, Hans J; Frost, Chris; Scahill, Rachael I; Hobbs, Nicola Z

    2014-03-21

    Diffusion tensor imaging (DTI) has shown microstructural abnormalities in patients with Huntington's Disease (HD) and work is underway to characterise how these abnormalities change with disease progression. Using methods that will be applied in longitudinal research, we sought to establish the reliability of DTI in early HD patients and controls. Test-retest reliability, quantified using the intraclass correlation coefficient (ICC), was assessed using region-of-interest (ROI)-based white matter atlas and voxelwise approaches on repeat scan data from 22 participants (10 early HD, 12 controls). T1 data was used to generate further ROIs for analysis in a reduced sample of 18 participants. The results suggest that fractional anisotropy (FA) and other diffusivity metrics are generally highly reliable, with ICCs indicating considerably lower within-subject compared to between-subject variability in both HD patients and controls. Where ICC was low, particularly for the diffusivity measures in the caudate and putamen, this was partly influenced by outliers. The analysis suggests that the specific DTI methods used here are appropriate for cross-sectional research in HD, and give confidence that they can also be applied longitudinally, although this requires further investigation. An important caveat for DTI studies is that test-retest reliability may not be evenly distributed throughout the brain whereby highly anisotropic white matter regions tended to show lower relative within-subject variability than other white or grey matter regions.

  3. Preliminary study of diffusion tensor MR on the cervical spinal cord in normal subjects

    International Nuclear Information System (INIS)

    Zheng Kuihong; Ma Lin; Guo Xinggao; Liang Li

    2006-01-01

    Objective: To investigate a simplified and practical strategy for MR diffusion tensor imaging (DTI) of the cervical spinal cord and acquire the normal values of DTI parameters in normal subjects, and to offer the basis for the research of the cervical spinal cord disorders. Methods: DTI examinations were performed in 36 consecutive healthy subjects by using SE-EPI sequence on the cervical spinal cord. The values of apparent diffusion coefficient (ADC), fractional anisotropy (FA), λ 1 , λ 2 , and λ 3 were measured in regions of interest positioned in the normal cervical cords. Results: All 36 subjects completed the examinations. The cervical spinal cords were clearly demonstrated on the postprocessing images, and there were no obvious artifacts on the diffusion tensor images. The average value of ADC was (914.44±82.61) x 10 -6 mm 2 /s and FA was (593.84±52.22) x 10 -3 . The diffusivity components parallel (λ 1 ) and orthogonal (λ 2 and λ 3 ) to the longitudinal axes of the spinal cord were (1585.10±130.07) x 10 -6 mm 2 /s, (559.84±66.49) x 10 -6 mm 2 /s, and (613.28±128.71) x 10 -6 mm 2 /s, respectively. The value of λ 1 was significantly higher than that of λ 2 and λ 3 (P 2 and λ 3 (P>0.05). The value of 2λ 1 /(λ 2 +λ 3 ) was 2.74± 0.32. Conclusion: The normal cervical spinal cord can be well demonstrated in vivo by using DTI with SE-EPI sequence, and various parameters acquired on DTI are stable. The water diffusivity in the direction parallel to the longitudinal axes of the spinal cord is found to be higher than that in directions perpendicular to the longitudinal axes of the spinal cord, thus suggesting the cylindrical anisotropic characteristics in the cervical spinal cord. (authors)

  4. Determination of the Rotational Diffusion Tensor of Macromolecules in Solution from NMR Relaxation Data with a Combination of Exact and Approximate Methods—Application to the Determination of Interdomain Orientation in Multidomain Proteins

    Science.gov (United States)

    Ghose, Ranajeet; Fushman, David; Cowburn, David

    2001-04-01

    In this paper we present a method for determining the rotational diffusion tensor from NMR relaxation data using a combination of approximate and exact methods. The approximate method, which is computationally less intensive, computes values of the principal components of the diffusion tensor and estimates the Euler angles, which relate the principal axis frame of the diffusion tensor to the molecular frame. The approximate values of the principal components are then used as starting points for an exact calculation by a downhill simplex search for the principal components of the tensor over a grid of the space of Euler angles relating the diffusion tensor frame to the molecular frame. The search space of Euler angles is restricted using the tensor orientations calculated using the approximate method. The utility of this approach is demonstrated using both simulated and experimental relaxation data. A quality factor that determines the extent of the agreement between the measured and predicted relaxation data is provided. This approach is then used to estimate the relative orientation of SH3 and SH2 domains in the SH(32) dual-domain construct of Abelson kinase complexed with a consolidated ligand.

  5. Determination of the rotational diffusion tensor of macromolecules in solution from nmr relaxation data with a combination of exact and approximate methods--application to the determination of interdomain orientation in multidomain proteins.

    Science.gov (United States)

    Ghose, R; Fushman, D; Cowburn, D

    2001-04-01

    In this paper we present a method for determining the rotational diffusion tensor from NMR relaxation data using a combination of approximate and exact methods. The approximate method, which is computationally less intensive, computes values of the principal components of the diffusion tensor and estimates the Euler angles, which relate the principal axis frame of the diffusion tensor to the molecular frame. The approximate values of the principal components are then used as starting points for an exact calculation by a downhill simplex search for the principal components of the tensor over a grid of the space of Euler angles relating the diffusion tensor frame to the molecular frame. The search space of Euler angles is restricted using the tensor orientations calculated using the approximate method. The utility of this approach is demonstrated using both simulated and experimental relaxation data. A quality factor that determines the extent of the agreement between the measured and predicted relaxation data is provided. This approach is then used to estimate the relative orientation of SH3 and SH2 domains in the SH(32) dual-domain construct of Abelson kinase complexed with a consolidated ligand. Copyright 2001 Academic Press.

  6. Reconstruction of white matter fibre tracts using diffusion kurtosis tensor imaging at 1.5T: Pre-surgical planning in patients with gliomas.

    Science.gov (United States)

    Leote, Joao; Nunes, Rita G; Cerqueira, Luis; Loução, Ricardo; Ferreira, Hugo A

    2018-01-01

    Tractography studies for pre-surgical planning of primary brain tumors is typically done using diffusion tensor imaging (DTI), which cannot resolve crossing, kissing or highly angulated fibres. Tractography based on the estimation of the diffusion kurtosis (DK) tensor was recently demonstrated to enable tackling these limitations. However, its use in the clinical context at low 1.5T field has not yet been reported. To evaluate if the estimation of whole-brain tractography using the DK tensor is feasible for pre-surgical investigation of patients with brain tumors at 1.5T. Eight healthy subjects and 3 patients with brain tumors were scanned at 1.5T using a 12-channel head coil. Diffusion-weighted images were acquired with repetition/echo times of 5800/107 ms, 82 × 82 resolution, 3 × 3 × 3 mm 3 voxel size, b-values of 0, 1000, 2000 s/mm 2 and 64 gradient sensitising directions. Whole-brain tractography was estimated using the DK tensor and corticospinal tracts (CST) were isolated using regions-of-interest placed at the cerebral peduncles and motor gyrus. Tract size, DK metrics and CST deviation index (highest curvature point) were compared between healthy subjects and patients. Tract sizes did not differ between groups. The CST deviation index was significantly higher in patients compared to healthy subjects. Fractional anisotropy was significantly lower in patients, with higher mean kurtosis asymmetry index at the highest curvature point in patients. Corticospinal fibre bundles estimated using DK tensor in a 1.5T scanner presented similar properties in patients with brain gliomas as those reported in the literature using DTI-based tractography.

  7. Weighted Mean of Signal Intensity for Unbiased Fiber Tracking of Skeletal Muscles: Development of a New Method and Comparison With Other Correction Techniques.

    Science.gov (United States)

    Giraudo, Chiara; Motyka, Stanislav; Weber, Michael; Resinger, Christoph; Thorsten, Feiweier; Traxler, Hannes; Trattnig, Siegfried; Bogner, Wolfgang

    2017-08-01

    The aim of this study was to investigate the origin of random image artifacts in stimulated echo acquisition mode diffusion tensor imaging (STEAM-DTI), assess the role of averaging, develop an automated artifact postprocessing correction method using weighted mean of signal intensities (WMSIs), and compare it with other correction techniques. Institutional review board approval and written informed consent were obtained. The right calf and thigh of 10 volunteers were scanned on a 3 T magnetic resonance imaging scanner using a STEAM-DTI sequence.Artifacts (ie, signal loss) in STEAM-based DTI, presumably caused by involuntary muscle contractions, were investigated in volunteers and ex vivo (ie, human cadaver calf and turkey leg using the same DTI parameters as for the volunteers). An automated postprocessing artifact correction method based on the WMSI was developed and compared with previous approaches (ie, iteratively reweighted linear least squares and informed robust estimation of tensors by outlier rejection [iRESTORE]). Diffusion tensor imaging and fiber tracking metrics, using different averages and artifact corrections, were compared for region of interest- and mask-based analyses. One-way repeated measures analysis of variance with Greenhouse-Geisser correction and Bonferroni post hoc tests were used to evaluate differences among all tested conditions. Qualitative assessment (ie, images quality) for native and corrected images was performed using the paired t test. Randomly localized and shaped artifacts affected all volunteer data sets. Artifact burden during voluntary muscle contractions increased on average from 23.1% to 77.5% but were absent ex vivo. Diffusion tensor imaging metrics (mean diffusivity, fractional anisotropy, radial diffusivity, and axial diffusivity) had a heterogeneous behavior, but in the range reported by literature. Fiber track metrics (number, length, and volume) significantly improved in both calves and thighs after artifact

  8. Fetal diffusion tensor quantification of brainstem pathology in Chiari II malformation

    Energy Technology Data Exchange (ETDEWEB)

    Woitek, Ramona; Prayer, Daniela; Weber, Michael; Schoepf, Veronika; Furtner, Julia; Asenbaum, Ulrika; Kasprian, Gregor [Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria); Amann, Gabriele [Medical University of Vienna, Department of Clinical Pathology, Vienna (Austria); Seidl, Rainer [Medical University of Vienna, Department of Paediatrics and Adolescent Medicine, Vienna (Austria); Bettelheim, Dieter [Medical University of Vienna, Department of Obstetrics and Gynecology, Vienna (Austria); Brugger, Peter C. [Medical University of Vienna, Center for Anatomy and Cell Biology, Vienna (Austria)

    2016-05-15

    This prenatal MRI study evaluated the potential of diffusion tensor imaging (DTI) metrics to identify changes in the midbrain of fetuses with Chiari II malformations compared to fetuses with mild ventriculomegaly, hydrocephalus and normal CNS development. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from a region of interest (ROI) in the midbrain of 46 fetuses with normal CNS, 15 with Chiari II malformations, eight with hydrocephalus and 12 with mild ventriculomegaly. Fetuses with different diagnoses were compared group-wise after age-matching. Axial T2W-FSE sequences and single-shot echo planar DTI sequences (16 non-collinear diffusion gradient-encoding directions, b-values of 0 and 700 s/mm{sup 2}, 1.5 Tesla) were evaluated retrospectively. In Chiari II malformations, FA was significantly higher than in age-matched fetuses with a normal CNS (p =.003), while ADC was not significantly different. No differences in DTI metrics between normal controls and fetuses with hydrocephalus or vetriculomegaly were detected. DTI can detect and quantify parenchymal alterations of the fetal midbrain in Chiari II malformations. Therefore, in cases of enlarged fetal ventricles, FA of the fetal midbrain may contribute to the differentiation between Chiari II malformation and other entities. (orig.)

  9. Histogram Analysis of Diffusion Tensor Imaging Parameters in Pediatric Cerebellar Tumors.

    Science.gov (United States)

    Wagner, Matthias W; Narayan, Anand K; Bosemani, Thangamadhan; Huisman, Thierry A G M; Poretti, Andrea

    2016-05-01

    Apparent diffusion coefficient (ADC) values have been shown to assist in differentiating cerebellar pilocytic astrocytomas and medulloblastomas. Previous studies have applied only ADC measurements and calculated the mean/median values. Here we investigated the value of diffusion tensor imaging (DTI) histogram characteristics of the entire tumor for differentiation of cerebellar pilocytic astrocytomas and medulloblastomas. Presurgical DTI data were analyzed with a region of interest (ROI) approach to include the entire tumor. For each tumor, histogram-derived metrics including the 25th percentile, 75th percentile, and skewness were calculated for fractional anisotropy (FA) and mean (MD), axial (AD), and radial (RD) diffusivity. The histogram metrics were used as primary predictors of interest in a logistic regression model. Statistical significance levels were set at p histogram skewness showed statistically significant differences for MD between low- and high-grade tumors (P = .008). The 25th percentile for MD yields the best results for the presurgical differentiation between pediatric cerebellar pilocytic astrocytomas and medulloblastomas. The analysis of other DTI metrics does not provide additional diagnostic value. Our study confirms the diagnostic value of the quantitative histogram analysis of DTI data in pediatric neuro-oncology. Copyright © 2015 by the American Society of Neuroimaging.

  10. Fetal diffusion tensor quantification of brainstem pathology in Chiari II malformation

    International Nuclear Information System (INIS)

    Woitek, Ramona; Prayer, Daniela; Weber, Michael; Schoepf, Veronika; Furtner, Julia; Asenbaum, Ulrika; Kasprian, Gregor; Amann, Gabriele; Seidl, Rainer; Bettelheim, Dieter; Brugger, Peter C.

    2016-01-01

    This prenatal MRI study evaluated the potential of diffusion tensor imaging (DTI) metrics to identify changes in the midbrain of fetuses with Chiari II malformations compared to fetuses with mild ventriculomegaly, hydrocephalus and normal CNS development. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from a region of interest (ROI) in the midbrain of 46 fetuses with normal CNS, 15 with Chiari II malformations, eight with hydrocephalus and 12 with mild ventriculomegaly. Fetuses with different diagnoses were compared group-wise after age-matching. Axial T2W-FSE sequences and single-shot echo planar DTI sequences (16 non-collinear diffusion gradient-encoding directions, b-values of 0 and 700 s/mm 2 , 1.5 Tesla) were evaluated retrospectively. In Chiari II malformations, FA was significantly higher than in age-matched fetuses with a normal CNS (p =.003), while ADC was not significantly different. No differences in DTI metrics between normal controls and fetuses with hydrocephalus or vetriculomegaly were detected. DTI can detect and quantify parenchymal alterations of the fetal midbrain in Chiari II malformations. Therefore, in cases of enlarged fetal ventricles, FA of the fetal midbrain may contribute to the differentiation between Chiari II malformation and other entities. (orig.)

  11. In vivo assessment of peripheral nerve regeneration by diffusion tensor imaging.

    Science.gov (United States)

    Morisaki, Shinsuke; Kawai, Yuko; Umeda, Masahiro; Nishi, Mayumi; Oda, Ryo; Fujiwara, Hiroyoshi; Yamada, Kei; Higuchi, Toshihiro; Tanaka, Chuzo; Kawata, Mitsuhiro; Kubo, Toshikazu

    2011-03-01

    To evaluate the sensitivity of diffusion tensor imaging (DTI) in assessing peripheral nerve regeneration in vivo. We assessed the changes in the DTI parameters and histological analyses after nerve injury to examine degeneration and regeneration in the rat sciatic nerves. For magnetic resonance imaging (MRI), 16 rats were randomly divided into two groups: group P (permanently crushed; n = 7) and group T (temporally crushed; n = 9). Serial MRI of the right leg was performed before the operation, and then performed at the timepoints of 1, 2, 3, and 4 weeks after the crush injury. The changes in fractional anisotropy (FA), axial diffusivity (λ(∥)), and radial diffusivity (λ(⟂)) were quantified. For histological analyses, the number of axons and the myelinated axon areas were quantified. Decreased FA and increased λ(⟂) were observed in the degenerative phase, and increased FA and decreased λ(⟂) were observed in the regenerative phase. The changes in FA and λ(⟂) were strongly correlated with histological changes, including axonal and myelin regeneration. DTI parameters, especially λ(⟂) , can be good indicators for peripheral nerve regeneration and can be applied as noninvasive diagnostic tools for a variety of neurological diseases. Copyright © 2011 Wiley-Liss, Inc.

  12. Diagnosis of Lumbar Foraminal Stenosis using Diffusion Tensor Imaging.

    Science.gov (United States)

    Eguchi, Yawara; Ohtori, Seiji; Suzuki, Munetaka; Oikawa, Yasuhiro; Yamanaka, Hajime; Tamai, Hiroshi; Kobayashi, Tatsuya; Orita, Sumihisa; Yamauchi, Kazuyo; Suzuki, Miyako; Aoki, Yasuchika; Watanabe, Atsuya; Kanamoto, Hirohito; Takahashi, Kazuhisa

    2016-02-01

    Diagnosis of lumbar foraminal stenosis remains difficult. Here, we report on a case in which bilateral lumbar foraminal stenosis was difficult to diagnose, and in which diffusion tensor imaging (DTI) was useful. The patient was a 52-year-old woman with low back pain and pain in both legs that was dominant on the right. Right lumbosacral nerve compression due to a massive uterine myoma was apparent, but the leg pain continued after a myomectomy was performed. No abnormalities were observed during nerve conduction studies. Computed tomography and magnetic resonance imaging indicated bilateral L5 lumbar foraminal stenosis. DTI imaging was done. The extraforaminal values were decreased and tractography was interrupted in the foraminal region. Bilateral L5 vertebral foraminal stenosis was treated by transforaminal lumbar interbody fusion and the pain in both legs disappeared. The case indicates the value of DTI for diagnosing vertebral foraminal stenosis.

  13. Potential of diffusion tensor MRI in the assessment of periventricular leukomalacia

    International Nuclear Information System (INIS)

    Fan, G.G.; Yu, B.; Quan, S.M.; Sun, B.H.; Guo, Q.Y.

    2006-01-01

    AIM: To investigate magnetic resonance (MR) diffusion tensor imaging (DTI) and fibre tractography in the assessment of altered major white matter (WM) fibre tracts in periventricular leukomalacia (PVL). MATERIALS AND METHODS: Twelve children (male:female=7:5, age range 3-10 years; mean age=6.5 years) who had suffered PVL were included in this study. Meanwhile, Twelve age-matched normal controls (male:female=6:6, age range 4-12 years; mean age=7.3 years) with normal MRI findings and no neurological abnormalities were recruited for comparison. DTI was performed with 15 different diffusion gradient directions and DTI colour maps were created from fractional anisotropy (FA) values and the three vector elements. To identify alteration of WM fibre tracts in patient of PVL quantitatively, FA values on diffusion tensor colour maps were compared between the patients and controls. Quantitative analysis was performed using the regions of interest (ROI) method settled on the central part of all identifiable WM fibres, including the corticospinal tract (CST) in the brainstem, middle cerebellar peduncle (MCP), medial lemniscus (ML), anterior/posterior limb of internal capsule (ICAL/ICPL), arcuate fasciculus (AF), posterior thalamic radiation (PTR), genu of corpus callosum (GCC), splenium of corpus callosum (SCC), corona radiata (CR), cingulum (CG), and superior longitudinal fasciculus (SLF). The averaged FA value of each WM fibre was measured and summarized as the mean±standard deviation (SD). All data were analysed by paired Student's t-test. A p-value of less than 0.05 was considered to indicate statistical significance. RESULTS: Visual investigation of WM fibre tracts showed that the ICAL, brainstem CST, ML, MCP, and external capsule (EC) was similar in controls and subjects. However, the ICPL, AF, PTR, CR, CG, SLF and corpus callosum, were all attenuated in size. All 12 cases of PVL showed a significant mean FA reduction in the ICPL, AF, PTR, CR, CG, SLF, SCC, and GCC in

  14. Reducing surgical levels by paraspinal mapping and diffusion tensor imaging techniques in lumbar spinal stenosis

    OpenAIRE

    Chen, Hua-Biao; Wan, Qi; Xu, Qi-Feng; Chen, Yi; Bai, Bo

    2016-01-01

    Background Correlating symptoms and physical examination findings with surgical levels based on common imaging results is not reliable. In patients who have no concordance between radiological and clinical symptoms, the surgical levels determined by conventional magnetic resonance imaging (MRI) and neurogenic examination (NE) may lead to a more extensive surgery and significant complications. We aimed to confirm that whether the use of diffusion tensor imaging (DTI) and paraspinal mapping (PM...

  15. Piriformis muscle syndrome with assessment of sciatic nerve using diffusion tensor imaging and tractography: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Keizo; Goto, Tomohiro; Takasago, Tomoya; Hamada, Daisuke; Sairyo, Koichi [The University of Tokushima Graduate School, Department of Orthopedics, Institute of Health Biosciences, Tokushima (Japan)

    2017-10-15

    Piriformis muscle syndrome (PMS) is difficult to diagnose by objective evaluation of sciatic nerve injury. Here we report a case of PMS diagnosed by diffusion tensor imaging (DTI) and tractography of the sciatic nerve, which can assess and visualize the extent of nerve injury. The patient was a 53-year-old man with a 2-year history of continuous pain and numbness in the left leg. His symptoms worsened when sitting. Physical examination, including sensorimotor neurologic tests, the deep tendon reflex test, and the straight leg raise test, revealed no specific findings. The hip flexion adduction and internal rotation test and resisted contraction maneuvers for the piriformis muscle were positive. There were no abnormal findings on magnetic resonance imaging (MRI) of the lumbar spine. The transverse diameter of piriformis muscle was slightly thicker in affected side on MRI of the pelvis. A single DTI sequence was performed during MRI of the pelvis. Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve were quantified at three levels using the fiber-tracking method. FA values were significantly lower and ADC values were significantly higher distal to the piriformis muscle. We performed endoscopic-assisted resection of the piriformis tendon. Intraoperatively, the motor-evoked potentials in the left gastrocnemius were improved by resection of the piriformis tendon. The patient's symptoms improved immediately after surgery. There was no significant difference in FA or ADC at any level between the affected side and the unaffected side 3 months postoperatively. MRI-DTI may aid the diagnosis of PMS. (orig.)

  16. Piriformis muscle syndrome with assessment of sciatic nerve using diffusion tensor imaging and tractography: a case report.

    Science.gov (United States)

    Wada, Keizo; Goto, Tomohiro; Takasago, Tomoya; Hamada, Daisuke; Sairyo, Koichi

    2017-10-01

    Piriformis muscle syndrome (PMS) is difficult to diagnose by objective evaluation of sciatic nerve injury. Here we report a case of PMS diagnosed by diffusion tensor imaging (DTI) and tractography of the sciatic nerve, which can assess and visualize the extent of nerve injury. The patient was a 53-year-old man with a 2-year history of continuous pain and numbness in the left leg. His symptoms worsened when sitting. Physical examination, including sensorimotor neurologic tests, the deep tendon reflex test, and the straight leg raise test, revealed no specific findings. The hip flexion adduction and internal rotation test and resisted contraction maneuvers for the piriformis muscle were positive. There were no abnormal findings on magnetic resonance imaging (MRI) of the lumbar spine. The transverse diameter of piriformis muscle was slightly thicker in affected side on MRI of the pelvis. A single DTI sequence was performed during MRI of the pelvis. Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve were quantified at three levels using the fiber-tracking method. FA values were significantly lower and ADC values were significantly higher distal to the piriformis muscle. We performed endoscopic-assisted resection of the piriformis tendon. Intraoperatively, the motor-evoked potentials in the left gastrocnemius were improved by resection of the piriformis tendon. The patient's symptoms improved immediately after surgery. There was no significant difference in FA or ADC at any level between the affected side and the unaffected side 3 months postoperatively. MRI-DTI may aid the diagnosis of PMS.

  17. Piriformis muscle syndrome with assessment of sciatic nerve using diffusion tensor imaging and tractography: a case report

    International Nuclear Information System (INIS)

    Wada, Keizo; Goto, Tomohiro; Takasago, Tomoya; Hamada, Daisuke; Sairyo, Koichi

    2017-01-01

    Piriformis muscle syndrome (PMS) is difficult to diagnose by objective evaluation of sciatic nerve injury. Here we report a case of PMS diagnosed by diffusion tensor imaging (DTI) and tractography of the sciatic nerve, which can assess and visualize the extent of nerve injury. The patient was a 53-year-old man with a 2-year history of continuous pain and numbness in the left leg. His symptoms worsened when sitting. Physical examination, including sensorimotor neurologic tests, the deep tendon reflex test, and the straight leg raise test, revealed no specific findings. The hip flexion adduction and internal rotation test and resisted contraction maneuvers for the piriformis muscle were positive. There were no abnormal findings on magnetic resonance imaging (MRI) of the lumbar spine. The transverse diameter of piriformis muscle was slightly thicker in affected side on MRI of the pelvis. A single DTI sequence was performed during MRI of the pelvis. Fractional anisotropy (FA) and the apparent diffusion coefficient (ADC) of the sciatic nerve were quantified at three levels using the fiber-tracking method. FA values were significantly lower and ADC values were significantly higher distal to the piriformis muscle. We performed endoscopic-assisted resection of the piriformis tendon. Intraoperatively, the motor-evoked potentials in the left gastrocnemius were improved by resection of the piriformis tendon. The patient's symptoms improved immediately after surgery. There was no significant difference in FA or ADC at any level between the affected side and the unaffected side 3 months postoperatively. MRI-DTI may aid the diagnosis of PMS. (orig.)

  18. Serial Diffusion Tensor Imaging of the Optic Radiations after Acute Optic Neuritis

    Directory of Open Access Journals (Sweden)

    Scott C. Kolbe

    2016-01-01

    Full Text Available Previous studies have reported diffusion tensor imaging (DTI changes within the optic radiations of patients after optic neuritis (ON. We aimed to study optic radiation DTI changes over 12 months following acute ON and to study correlations between DTI parameters and damage to the optic nerve and primary visual cortex (V1. We measured DTI parameters [fractional anisotropy (FA, axial diffusivity (AD, radial diffusivity (RD, and mean diffusivity (MD] from the optic radiations of 38 acute ON patients at presentation and 6 and 12 months after acute ON. In addition, we measured retinal nerve fibre layer thickness, visual evoked potential amplitude, optic radiation lesion load, and V1 thickness. At baseline, FA was reduced and RD and MD were increased compared to control. Over 12 months, FA reduced in patients at an average rate of −2.6% per annum (control = −0.51%; p=0.006. Change in FA, RD, and MD correlated with V1 thinning over 12 months (FA: R=0.450, p=0.006; RD: R=-0.428, p=0.009; MD: R=-0.365, p=0.029. In patients with no optic radiation lesions, AD significantly correlated with RNFL thinning at 12 months (R=0.489, p=0.039. In conclusion, DTI can detect optic radiation changes over 12 months following acute ON that correlate with optic nerve and V1 damage.

  19. Diffusion tensor imaging of partial intractable epilepsy

    International Nuclear Information System (INIS)

    Dumas de la Roque, Anne; Oppenheim, Catherine; Rodrigo, Sebastian; Meder, Jean-Francois; Chassoux, Francine; Devaux, Bertrand; Beuvon, Frederic; Daumas-Duport, Catherine

    2005-01-01

    Our aim was to assess the value of diffusion tensor imaging (DTI) in patients with partial intractable epilepsy. We used DTI (25 non-collinear directions) in 15 patients with a cortical lesion on conventional MRI. Fractional anisotropy (FA) was measured in the internal capsule, and in the normal-appearing white matter (WM), adjacent tothe lesion, and away from the lesion, at a set distance of 2-3 cm. In each patient, increased or decreased FA measurements were those that varied from mirror values using an arbitrary 10% threshold. Over the whole population, ipsi- and contralateral FA measurements were also compared using a Wilcoxon test (p<0.05). Over the whole population, FA was significantly reduced in the WM adjacent to and away from the lesion, whilst being normal in the internal capsule. FA was reduced by more than 10% in the WM adjacent to and distant from the lesion in 13 and 12 patients respectively. For nine of the ten patients for whom the surgical resection encompassed the limits of the lesion on conventional MRI, histological data showed WM alterations (gliosis, axonal loss, abnormal cells). DTI often reveals WM abnormalities that are undetected on conventional MRI in patients with partial intractable epilepsy. (orig.)

  20. The Impact of Diffusion Tensor Imaging Fiber Tracking of the Corticospinal Tract Based on Navigated Transcranial Magnetic Stimulation on Surgery of Motor-Eloquent Brain Lesions.

    Science.gov (United States)

    Raffa, Giovanni; Conti, Alfredo; Scibilia, Antonino; Cardali, Salvatore Massimiliano; Esposito, Felice; Angileri, Filippo Flavio; La Torre, Domenico; Sindorio, Carmela; Abbritti, Rosaria Viola; Germanò, Antonino; Tomasello, Francesco

    2017-11-29

    Navigated transcranial magnetic stimulation (nTMS) enables preoperative mapping of the motor cortex (M1). The combination of nTMS with diffusion tensor imaging fiber tracking (DTI-FT) of the corticospinal tract (CST) has been described; however, its impact on surgery of motor-eloquent lesions has not been addressed. To analyze the impact of nTMS-based mapping on surgery of motor-eloquent lesions. In this retrospective case-control study, we reviewed the data of patients operated for suspected motor-eloquent lesions between 2012 and 2015. The patients underwent nTMS mapping of M1 and, from 2014, nTMS-based DTI-FT of the CST. The impact on the preoperative risk/benefit analysis, surgical strategy, craniotomy size, extent of resection (EOR), and outcome were compared with a control group. We included 35 patients who underwent nTMS mapping of M1 (group A), 35 patients who also underwent nTMS-based DTI-FT of the CST (group B), and a control group composed of 35 patients treated without nTMS (group C). The patients in groups A and B received smaller craniotomies (P = .01; P = .001), had less postoperative seizures (P = .02), and a better postoperative motor performance (P = .04) and Karnofsky Performance Status (P = .009) than the controls. Group B exhibited an improved risk/benefit analysis (P = .006), an increased EOR of nTMS-negative lesions in absence of preoperative motor deficits (P = .01), and less motor and Karnofsky Performance Status worsening in case of preoperative motor deficits (P = .02, P = .03) than group A. nTMS-based mapping enables a tailored surgical approach for motor-eloquent lesions. It may improve the risk/benefit analysis, EOR and outcome, particularly when nTMS-based DTI-FT is performed. Copyright © 2017 by the Congress of Neurological Surgeons

  1. The optimal trackability threshold of fractional anisotropy for diffusion tensor tractography of the corticospinal tract

    International Nuclear Information System (INIS)

    Kunimatsu, Akira; Aoki, Shigeki; Masutani, Yoshitaka; Abe, Osamu; Hayashi, Naoto; Mori, Harushi; Masumoto, Tomohiko; Ohtomo, Kuni

    2004-01-01

    In order to ensure that three-dimensional diffusion tensor tractography (3D-DTT) of the corticospinal tract (CST), is performed accurately and efficiently, we set out to find the optimal lower threshold of fractional anisotropy (FA) below which tract elongation is terminated (trackability threshold). Thirteen patients with acute or early subacute ischemic stroke causing motor deficits were enrolled in this study. We performed 3D-DTT of the CST with diffusion tensor MR (magnetic resonance) imaging. We segmented the CST and established a cross-section of the CST in a transaxial plane as a region of interest. Thus, we selectively measured the FA values of the right and left corticospinal tracts at the level of the cerebral peduncle, the posterior limb of the internal capsule, and the centrum semiovale. The FA values of the CST were also measured on the affected side at the level where the clinically relevant infarction was present in isotropic diffusion-weighted imaging. 3D-DTT allowed us to selectively measure the FA values of the CST. Among the 267 regions of interest we measured, the minimum FA value was 0.22. The FA values of the CST were smaller and more variable in the centrum semiovale than in the other regions. The mean minus twice the standard deviation of the FA values of the CST in the centrum semiovale was calculated at 0.22 on the normal unaffected side and 0.16 on the affected side. An FA value of about 0.20 was found to be the optimal trackability threshold. (author)

  2. Characterizing Intraorbital Optic Nerve Changes on Diffusion Tensor Imaging in Thyroid Eye Disease Before Dysthyroid Optic Neuropathy.

    Science.gov (United States)

    Lee, Hwa; Lee, Young Hen; Suh, Sang-Il; Jeong, Eun-Kee; Baek, Sehyun; Seo, Hyung Suk

    The aim of this study was to determine whether the optic nerve is affected by thyroid eye disease (TED) before the development of dysthyroid optic neuropathy with diffusion-tensor imaging (DTI). Twenty TED patients and 20 controls were included. The mean, axial, and radial diffusivities and fractional anisotropy (FA) value were measured at the optic nerves in DTI. Extraocular muscle diameters were measured on computed tomography. The diffusivities and FA of the optic nerves were compared between TED and controls and between active and inactive stages of TED. The correlations between these DTI parameters and the clinical features were determined. The mean, axial, and radial diffusivities were lower in TED compared with the controls (P optic nerve before dysthyroid optic neuropathy in TED. The FA, in particular, reflected TED activity and severity.

  3. Long-Term Follow-up of a Patient with Traumatic Brain Injury Using Diffusion Tensor Imaging

    International Nuclear Information System (INIS)

    Skoglund, T.S.; Nilsson, D.; Ljungberg, M.; Joensson, L.; Rydenhag, B.

    2008-01-01

    This case report describes a patient who sustained severe head trauma with diffuse axonal injury (DAI). Examination with magnetic resonance diffusion tensor imaging (MR-DTI), 6 days post-injury, showed a severe reduction in fractional anisotropy (FA) in the rostral pons containing the corticospinal tract, which correlated to the patient's severe hemiparesis. By 18 months post-accident, the patient had recovered completely and conventional MRI showed no pathology. However, although her FA values in the rostral pons had increased, they were still not normalized. It seems that a complete normalization of the FA values is not required to achieve clinical recovery, and that MR-DTI seems to be more sensitive to DAI compared to conventional MRI

  4. Long-Term Follow-up of a Patient with Traumatic Brain Injury Using Diffusion Tensor Imaging

    Energy Technology Data Exchange (ETDEWEB)

    Skoglund, T.S.; Nilsson, D.; Ljungberg, M.; Joensson, L.; Rydenhag, B. (Dept. of Neurosurgery, Dept. of Medical Physics and Biomedical Engineering, and Dept. of Radiology, Sahlgrenska Univ. Hospital, Goeteborg (Sweden))

    2008-02-15

    This case report describes a patient who sustained severe head trauma with diffuse axonal injury (DAI). Examination with magnetic resonance diffusion tensor imaging (MR-DTI), 6 days post-injury, showed a severe reduction in fractional anisotropy (FA) in the rostral pons containing the corticospinal tract, which correlated to the patient's severe hemiparesis. By 18 months post-accident, the patient had recovered completely and conventional MRI showed no pathology. However, although her FA values in the rostral pons had increased, they were still not normalized. It seems that a complete normalization of the FA values is not required to achieve clinical recovery, and that MR-DTI seems to be more sensitive to DAI compared to conventional MRI

  5. Potential long-term effects of MDMA on the basal ganglia-thalamocortical circuit: a proton MR spectroscopy and diffusion-tensor imaging study.

    Science.gov (United States)

    Liu, Hua-Shan; Chou, Ming-Chung; Chung, Hsiao-Wen; Cho, Nai-Yu; Chiang, Shih-Wei; Wang, Chao-Ying; Kao, Hung-Wen; Huang, Guo-Shu; Chen, Cheng-Yu

    2011-08-01

    To investigate the effects of 3,4-methylenedioxymethamphetamine (MDMA, commonly known as "ecstasy") on the alterations of brain metabolites and anatomic tissue integrity related to the function of the basal ganglia-thalamocortical circuit by using proton magnetic resonance (MR) spectroscopy and diffusion-tensor MR imaging. This study was approved by a local institutional review board, and written informed consent was obtained from all subjects. Thirty-one long-term (>1 year) MDMA users and 33 healthy subjects were enrolled. Proton MR spectroscopy from the middle frontal cortex and bilateral basal ganglia and whole-brain diffusion-tensor MR imaging were performed with a 3.0-T system. Absolute concentrations of metabolites were computed, and diffusion-tensor data were registered to the International Consortium for Brain Mapping template to facilitate voxel-based group comparison. The mean myo-inositol level in the basal ganglia of MDMA users (left: 4.55 mmol/L ± 2.01 [standard deviation], right: 4.48 mmol/L ± 1.33) was significantly higher than that in control subjects (left: 3.25 mmol/L ± 1.30, right: 3.31 mmol/L ± 1.19) (P 50 voxels). Increased myo-inositol and Cho concentrations in the basal ganglia of MDMA users are suggestive of glial response to degenerating serotonergic functions. The abnormal metabolic changes in the basal ganglia may consequently affect the inhibitory effect of the basal ganglia to the thalamus, as suggested by the increased FA in the thalamus and abnormal changes in water diffusion in the corresponding basal ganglia-thalamocortical circuit. © RSNA, 2011.

  6. Methodological improvements in voxel-based analysis of diffusion tensor images: applications to study the impact of apolipoprotein E on white matter integrity.

    Science.gov (United States)

    Newlander, Shawn M; Chu, Alan; Sinha, Usha S; Lu, Po H; Bartzokis, George

    2014-02-01

    To identify regional differences in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) using customized preprocessing before voxel-based analysis (VBA) in 14 normal subjects with the specific genes that decrease (apolipoprotein [APO] E ε2) and that increase (APOE ε4) the risk of Alzheimer's disease. Diffusion tensor images (DTI) acquired at 1.5 Tesla were denoised with a total variation tensor regularization algorithm before affine and nonlinear registration to generate a common reference frame for the image volumes of all subjects. Anisotropic and isotropic smoothing with varying kernel sizes was applied to the aligned data before VBA to determine regional differences between cohorts segregated by allele status. VBA on the denoised tensor data identified regions of reduced FA in APOE ε4 compared with the APOE ε2 healthy older carriers. The most consistent results were obtained using the denoised tensor and anisotropic smoothing before statistical testing. In contrast, isotropic smoothing identified regional differences for small filter sizes alone, emphasizing that this method introduces bias in FA values for higher kernel sizes. Voxel-based DTI analysis can be performed on low signal to noise ratio images to detect subtle regional differences in cohorts using the proposed preprocessing techniques. Copyright © 2013 Wiley Periodicals, Inc.

  7. Diffusion tensor imaging and tractography for assessment of renal allograft dysfunction - initial results

    Energy Technology Data Exchange (ETDEWEB)

    Hueper, Katja; Gutberlet, M.; Rodt, T.; Wacker, F.; Galanski, M.; Hartung, D. [Institute for Diagnostic and Interventional Radiology, Hannover Medical School - Germany, Hannover (Germany); Gwinner, W. [Clinic for Nephrology, Hannover Medical School - Germany, Hannover (Germany); Lehner, F. [Clinic for General, Abdominal and Transplant Surgery, Hannover Medical School - Germany, Hannover (Germany)

    2011-11-15

    To evaluate MR diffusion tensor imaging (DTI) as non-invasive diagnostic tool for detection of acute and chronic allograft dysfunction and changes of organ microstructure. 15 kidney transplanted patients with allograft dysfunction and 14 healthy volunteers were examined using a fat-saturated echo-planar DTI-sequence at 1.5 T (6 diffusion directions, b = 0, 600 s/mm{sup 2}). Mean apparent diffusion coefficient (ADC) and mean fractional anisotropy (FA) were calculated separately for the cortex and for the medulla and compared between healthy and transplanted kidneys. Furthermore, the correlation between diffusion parameters and estimated GFR was determined. The ADC in the cortex and in the medulla were lower in transplanted than in healthy kidneys (p < 0.01). Differences were more distinct for FA, especially in the renal medulla, with a significant reduction in allografts (p < 0.001). Furthermore, in transplanted patients a correlation between mean FA in the medulla and estimated GFR was observed (r = 0.72, p < 0.01). Tractography visualized changes in renal microstructure in patients with impaired allograft function. Changes in allograft function and microstructure can be detected and quantified using DTI. However, to prove the value of DTI for standard clinical application especially correlation of imaging findings and biopsy results is necessary. (orig.)

  8. Cortical grey matter and subcortical white matter brain microstructural changes in schizophrenia are localised and age independent: a case-control diffusion tensor imaging study.

    Science.gov (United States)

    Chiapponi, Chiara; Piras, Fabrizio; Piras, Federica; Fagioli, Sabrina; Caltagirone, Carlo; Spalletta, Gianfranco

    2013-01-01

    It is still unknown whether the structural brain impairments that characterize schizophrenia (SZ) worsen during the lifetime. Here, we aimed to describe age-related microstructural brain changes in cortical grey matter and subcortical white matter of patients affected by SZ. In this diffusion tensor imaging study, we included 69 patients diagnosed with SZ and 69 healthy control (HC) subjects, age and gender matched. We carried out analyses of covariance, with diagnosis as fixed factor and brain diffusion-related parameters as dependent variables, and controlled for the effect of education. White matter fractional anisotropy decreased in the entire age range spanned (18-65 years) in both SZ and HC and was significantly lower in younger patients with SZ, with no interaction (age by diagnosis) effect in fiber tracts including corpus callosum, corona radiata, thalamic radiations and external capsule. Also, grey matter mean diffusivity increased in the entire age range in both SZ and HC and was significantly higher in younger patients, with no age by diagnosis interaction in the left frontal operculum cortex, left insula and left planum polare and in the right temporal pole and right intracalcarine cortex. In individuals with SZ we found that localized brain cortical and white matter subcortical microstructural impairments appear early in life but do not worsen in the 18-65 year age range.

  9. Cortical grey matter and subcortical white matter brain microstructural changes in schizophrenia are localised and age independent: a case-control diffusion tensor imaging study.

    Directory of Open Access Journals (Sweden)

    Chiara Chiapponi

    Full Text Available It is still unknown whether the structural brain impairments that characterize schizophrenia (SZ worsen during the lifetime. Here, we aimed to describe age-related microstructural brain changes in cortical grey matter and subcortical white matter of patients affected by SZ. In this diffusion tensor imaging study, we included 69 patients diagnosed with SZ and 69 healthy control (HC subjects, age and gender matched. We carried out analyses of covariance, with diagnosis as fixed factor and brain diffusion-related parameters as dependent variables, and controlled for the effect of education. White matter fractional anisotropy decreased in the entire age range spanned (18-65 years in both SZ and HC and was significantly lower in younger patients with SZ, with no interaction (age by diagnosis effect in fiber tracts including corpus callosum, corona radiata, thalamic radiations and external capsule. Also, grey matter mean diffusivity increased in the entire age range in both SZ and HC and was significantly higher in younger patients, with no age by diagnosis interaction in the left frontal operculum cortex, left insula and left planum polare and in the right temporal pole and right intracalcarine cortex. In individuals with SZ we found that localized brain cortical and white matter subcortical microstructural impairments appear early in life but do not worsen in the 18-65 year age range.

  10. Oxygen diffusion coefficient in isolated chicken red and white skeletal muscle fibers in ontogenesis.

    Science.gov (United States)

    Baranov, V I; Belichenko, V M; Shoshenko, C A

    2000-09-01

    Oxygen diffusion from medium to cultured isolated muscle fibers from red gastrocnemius muscle (deep part) (RGM) and white pectoralis muscle (WPM) of embryonic and postnatal chickens (about 6 months) was explored. The intracellular effective O(2) diffusion coefficient (D(i)) in muscle fiber was calculated from a model of a cylindrical fiber with a uniform distribution of an oxygen sink based on these experimentally measured parameters: critical tension of O(2) (PO(2)) on the surface of a fiber, specific rate of O(2) consumption by a weight unit of muscle fibers (;VO(2)), and average diameter of muscle fibers. The results document the rapid hypertrophic growth of RGM fibers when compared to WPM fibers in the second half of the embryonic period and the higher values of;VO(2) and critical PO(2) during the ontogenetic period under study. The oxygen D(i) in RGM fibers of embryos and 1-day chickens was two to three times higher than observed for WPM fibers. For senior chickens, the oxygen D(i) value in RGM and WPM fibers does not differ. The D(i) of O(2) in both RGM and WPM fibers increased from 1.4-2.7 x 10(-8) to 90-95 x 10(-8) cm(2)/s with an ontogenetic increase in fiber diameter from 7. 5 to 67.0 microm. At all stages the oxygen D(i) values in RGM and WPM fibers are significantly lower than the O(2) diffusion coefficient in water: for 11-day embryos they are 889 and 1714 times lower and for adult individuals 25 and 27 times lower, respectively. Why oxygen D(i) values in RGM and WPM fibers are so low and why they are gradually increasing during the course of hypertrophic ontogenetic growth are still unclear. Copyright 2000 Academic Press.

  11. Monitoring In-Vivo the Mammary Gland Microstructure during Morphogenesis from Lactation to Post-Weaning Using Diffusion Tensor MRI.

    Science.gov (United States)

    Nissan, Noam; Furman-Haran, Edna; Shapiro-Feinberg, Myra; Grobgeld, Dov; Degani, Hadassa

    2017-09-01

    Lactation and the return to the pre-conception state during post-weaning are regulated by hormonal induced processes that modify the microstructure of the mammary gland, leading to changes in the features of the ductal / glandular tissue, the stroma and the fat tissue. These changes create a challenge in the radiological workup of breast disorder during lactation and early post-weaning. Here we present non-invasive MRI protocols designed to record in vivo high spatial resolution, T 2 -weighted images and diffusion tensor images of the entire mammary gland. Advanced imaging processing tools enabled tracking the changes in the anatomical and microstructural features of the mammary gland from the time of lactation to post-weaning. Specifically, by using diffusion tensor imaging (DTI) it was possible to quantitatively distinguish between the ductal / glandular tissue distention during lactation and the post-weaning involution. The application of the T 2 -weighted imaging and DTI is completely safe, non-invasive and uses intrinsic contrast based on differences in transverse relaxation rates and water diffusion rates in various directions, respectively. This study provides a basis for further in-vivo monitoring of changes during the mammary developmental stages, as well as identifying changes due to malignant transformation in patients with pregnancy associated breast cancer (PABC).

  12. Identification of ghost artifact using texture analysis in pediatric spinal cord diffusion tensor images.

    Science.gov (United States)

    Alizadeh, Mahdi; Conklin, Chris J; Middleton, Devon M; Shah, Pallav; Saksena, Sona; Krisa, Laura; Finsterbusch, Jürgen; Faro, Scott H; Mulcahey, M J; Mohamed, Feroze B

    2018-04-01

    Ghost artifacts are a major contributor to degradation of spinal cord diffusion tensor images. A multi-stage post-processing pipeline was designed, implemented and validated to automatically remove ghost artifacts arising from reduced field of view diffusion tensor imaging (DTI) of the pediatric spinal cord. A total of 12 pediatric subjects including 7 healthy subjects (mean age=11.34years) with no evidence of spinal cord injury or pathology and 5 patients (mean age=10.96years) with cervical spinal cord injury were studied. Ghost/true cords, labeled as region of interests (ROIs), in non-diffusion weighted b0 images were segmented automatically using mathematical morphological processing. Initially, 21 texture features were extracted from each segmented ROI including 5 first-order features based on the histogram of the image (mean, variance, skewness, kurtosis and entropy) and 16s-order feature vector elements, incorporating four statistical measures (contrast, correlation, homogeneity and energy) calculated from co-occurrence matrices in directions of 0°, 45°, 90° and 135°. Next, ten features with a high value of mutual information (MI) relative to the pre-defined target class and within the features were selected as final features which were input to a trained classifier (adaptive neuro-fuzzy interface system) to separate the true cord from the ghost cord. The implemented pipeline was successfully able to separate the ghost artifacts from true cord structures. The results obtained from the classifier showed a sensitivity of 91%, specificity of 79%, and accuracy of 84% in separating the true cord from ghost artifacts. The results show that the proposed method is promising for the automatic detection of ghost cords present in DTI images of the spinal cord. This step is crucial towards development of accurate, automatic DTI spinal cord post processing pipelines. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. New MRI technologies. Diffusion MRI and its application to functional neuroimaging and analyses of white matter integrity

    International Nuclear Information System (INIS)

    Kobayashi, Tetsuo

    2010-01-01

    Described is the technological aspect of MRI, MR diffusion-weighted imaging (MR-DWI), principles of its measurement and application for imaging the cerebral function and for aiding the quantitative diagnosis of brain diseases. The author explains the principle of MR imaging process; diffusion properties of water molecules, MR-DWI based on them and DW-fMRI of the brain; MR-diffusion tensor imaging (MR-DTI), its analysis and color acquisition, and tracking of white matter nerve fibers; analysis of white matter lesions by the tracking; and the new tracking method at the chiasm of nerve fascicles. The usual fMRI reflects the blood oxygen level depending (BOLD) signals whereas recently attracted DW-fMRI, the volume changes of nerve cells concomitant to nerve activation accompanying apparent changes of water diffusion coefficients in and out of cells which occur faster than BOLD signs, resulting in higher resolution of time and space. However, DWI requires the higher intensity of static magnetic field like 3T. MR-DTI acquires the anisotropic diffusion of water molecules using MR-DWI technique with application of 6 or more motion probing gradients, thus makes it possible to track the running directions of nerve fibers and capillary vessels, and is proposed to be a useful mean of specific fiber tracking in the white matter when displayed by 3 different colors exhibiting the directions like the right/left (x axis, red), anterior/posterior (y, green) and upper/lower (z, blue) sides of head. Recently, MR-DWI and MR-DTI have been found usable for pathogenic studies of brain diseases such as dementia. Tensor anisotropy is apparently lowered at the chiasm of nerve fascicles, the cause of tracking error, for which authors have developed a new method using the similarity of directional vector, not of tensor, before and behind the chiasm. As exemplified, MRI technology is further advancing even at present. (T.T.)

  14. Diffusion-weighted MR imaging of the brain. 2. ed.

    International Nuclear Information System (INIS)

    Moritani, Toshio; Ekholm, Sven; Westesson, Per-Lennart

    2009-01-01

    This practical-minded text helps the radiologist and the clinician understand diffusion-weighted MR imaging. The book's 15 chapters range from basic principles to interpretation of diffusion-weighted MR imaging and specific disease. In this second edition, diffusion tensor imaging (fractional anisotropy, color map and fiber tractography) is covered and a new chapter, on ''Diffusion-Weighted Imaging of Scalp and Skull Lesions,'' is included. The volume is updated by newly added cases accompanied by radiological and pathological images along with the most recent references. It is aimed at all those who are involved in neuroimaging, including: residents, fellows, staff, as well as neurologists and neurosurgeons. Diffusion-weighted MR imaging is widely accepted as a means to identify acute infarction but also to differentiate many other pathologic conditions. Understanding diffusion-weighted imaging is important for radiologists, neurologists, neurosurgeons as well as radiology technologists. (orig.)

  15. Comparison of Turbo Spin Echo and Echo Planar Imaging for intravoxel incoherent motion and diffusion tensor imaging of the kidney at 3 Tesla

    Energy Technology Data Exchange (ETDEWEB)

    Hilbert, Fabian; Wech, Tobias; Neubauer, Henning; Veldhoen, Simon; Bley, Thorsten Alexander; Koestler, Herbert [Wuerzburg Univ. (Germany). Inst. fuer Diagnostische und Interventionelle Radiologie

    2017-10-01

    Echo Planar Imaging (EPI) is most commonly applied to acquire diffusion-weighted MR-images. EPI is able to capture an entire image in very short time, but is prone to distortions and artifacts. In diffusion-weighted EPI of the kidney severe distortions may occur due to intestinal gas. Turbo Spin Echo (TSE) is robust against distortions and artifacts, but needs more time to acquire an entire image compared to EPI. Therefore, TSE is more sensitive to motion during the readout. In this study we compare diffusion-weighted TSE and EPI of the human kidney with regard to intravoxel incoherent motion (IVIM) and diffusion tensor imaging (DTI). Images were acquired with b-values between 0 and 750 s/mm{sup 2} with TSE and EPI. Distortions were observed with the EPI readout in all volunteers, while the TSE images were virtually distortion-free. Fractional anisotropy of the diffusion tensor was significantly lower for TSE than for EPI. All other parameters of DTI and IVIM were comparable for TSE and EPI. Especially the main diffusion directions yielded by TSE and EPI were similar. The results demonstrate that TSE is a worthwhile distortion-free alternative to EPI for diffusion-weighted imaging of the kidney at 3 Tesla.

  16. [Assessment of motor and sensory pathways of the brain using diffusion-tensor tractography in children with cerebral palsy].

    Science.gov (United States)

    Memedyarov, A M; Namazova-Baranova, L S; Ermolina, Y V; Anikin, A V; Maslova, O I; Karkashadze, M Z; Klochkova, O A

    2014-01-01

    Diffusion tensor tractography--a new method of magnetic resonance imaging, that allows to visualize the pathways of the brain and to study their structural-functional state. The authors investigated the changes in motor and sensory pathways of brain in children with cerebral palsy using routine magnetic resonance imaging and diffusion-tensor tractography. The main group consisted of 26 patients with various forms of cerebral palsy and the comparison group was 25 people with normal psychomotor development (aged 2 to 6 years) and MR-picture of the brain. Magnetic resonance imaging was performed on the scanner with the induction of a magnetic field of 1,5 Tesla. Coefficients of fractional anisotropy and average diffusion coefficient estimated in regions of the brain containing the motor and sensory pathways: precentral gyrus, posterior limb of the internal capsule, thalamus, posterior thalamic radiation and corpus callosum. Statistically significant differences (p cerebral palsy in relation to the comparison group. All investigated regions, the coefficients of fractional anisotropy in children with cerebral palsy were significantly lower, and the average diffusion coefficient, respectively, higher. These changes indicate a lower degree of ordering of the white matter tracts associated with damage and subsequent development of gliosis of varying severity in children with cerebral palsy. It is shown that microstructural damage localized in both motor and sensory tracts that plays a leading role in the development of the clinical picture of cerebral palsy.

  17. Motor function outcomes of pediatric patients with hemiplegic cerebral palsy after rehabilitation treatment: a diffusion tensor imaging study

    Directory of Open Access Journals (Sweden)

    Jin Hyun Kim

    2015-01-01

    Full Text Available Previous diffusion tensor imaging (DTI studies regarding pediatric patients with motor dysfunction have confirmed the correlation between DTI parameters of the injured corticospinal tract and the severity of motor dysfunction. There is also evidence that DTI parameters can help predict the prognosis of motor function of patients with cerebral palsy. But few studies are reported on the DTI parameters that can reflect the motor function outcomes of pediatric patients with hemiplegic cerebral palsy after rehabilitation treatment. In the present study, 36 pediatric patients with hemiplegic cerebral palsy were included. Before and after rehabilitation treatment, DTI was used to measure the fiber number (FN, fractional anisotropy (FA and apparent diffusion coefficient (ADC of bilateral corticospinal tracts. Functional Level of Hemiplegia scale (FxL was used to assess the therapeutic effect of rehabilitative therapy on clinical hemiplegia. Correlation analysis was performed to assess the statistical interrelationship between the change amount of DTI parameters and FxL. DTI findings obtained at the initial and follow-up evaluations demonstrated that more affected corticospinal tract yielded significantly decreased FN and FA values and significantly increased ADC value compared to the less affected corticospinal tract. Correlation analysis results showed that the change amount of FxL was positively correlated to FN and FA values, and the correlation to FN was stronger than the correlation to FA. The results suggest that FN and FA values can be used to evaluate the motor function outcomes of pediatric patients with hemiplegic cerebral palsy after rehabilitation treatment and FN is of more significance for evaluation.

  18. Age related diffusion and tractography changes in typically developing pediatric cervical and thoracic spinal cord

    Directory of Open Access Journals (Sweden)

    Mahdi Alizadeh

    Full Text Available Background and objective: Diffusion tensor imaging (DTI and diffusion tensor tractography (DTT are two techniques that can measure white matter integrity of the spinal cord. Recently, DTI indices have been shown to change with age. The purpose of this study is (a to evaluate the maturational states of the entire pediatric spinal cord using DTI and DTT indices including fractional anisotropy (FA, mean diffusivity (MD, mean length of white matter fiber tracts and tract density and (b to analyze the DTI and DTT parameters along the entire spinal cord as a function of spinal cord levels and age. Method: A total of 23 typically developing (TD pediatric subjects ranging in age from 6 to 16 years old (11.94 ± 3.26 (mean ± standard deviation, 13 females and 10 males were recruited, and scanned using 3.0 T MR scanner. Reduced FOV diffusion tensor images were acquired axially in the same anatomical location prescribed for the T2-weighted images to cover the entire spinal cord (C1-mid L1 levels. To mitigate motion induced artifacts, diffusion directional images were aligned with the reference image (b0 using a rigid body registration algorithm performed by in-house software developed in Matlab (MathWorks, Natick, Massachusetts. Diffusion tensor maps (FA and MD and streamline deterministic tractography were then generated from the motion corrected DTI dataset. DTI and DTT parameters were calculated by using ROIs drawn to encapsulate the whole cord along the entire spinal cord by an independent board certified neuroradiologist. These indices then were compared between two age groups (age group A = 6–11 years (n = 11 and age group B = 12–16 years (n = 12 based on similar standards and age definitions used for reporting spinal cord injury in the pediatric population. Standard least squared linear regression based on a restricted maximum likelihood (REML method was used to evaluate the relationship between age and DTI and

  19. An Adaptive Spectrally Weighted Structure Tensor Applied to Tensor Anisotropic Nonlinear Diffusion for Hyperspectral Images

    Science.gov (United States)

    Marin Quintero, Maider J.

    2013-01-01

    The structure tensor for vector valued images is most often defined as the average of the scalar structure tensors in each band. The problem with this definition is the assumption that all bands provide the same amount of edge information giving them the same weights. As a result non-edge pixels can be reinforced and edges can be weakened…

  20. Diffusion tensor MR imaging in neurofibromatosis type 1: expanding the knowledge of microstructural brain abnormalities

    International Nuclear Information System (INIS)

    Ferraz-Filho, Jose R.L.; Muniz, Marcos P.; Souza, Antonio S.; Rocha, Antonio J. da; Goloni-Bertollo, Eny M.; Pavarino-Bertelli, Erika C.

    2012-01-01

    Neurofibromatosis type 1 (NF1) is a hereditary disease with a dominant autosomal pattern. In children and adolescents, it is frequently associated with the appearance of T2-weighted hyperintensities in the brain's white matter. MRI with diffusion tensor imaging (DTI) is used to detect white matter abnormalities by measuring fractional anisotropy (FA). This study employed DTI to evaluate the relationship between FA patterns and the findings of T2 sequences, with the aim of improving our understanding of anatomical changes and microstructural brain abnormalities in individuals with NF1. Forty-four individuals with NF1 and 20 control subjects were evaluated. The comparative analysis of FA between NF1 and control groups was based on four predetermined anatomical regions of the brain hemispheres (basal ganglia, cerebellum, pons, thalamus) and related the presence or absence of T2-weighted hyperintensities in the brain, which are called unidentified bright objects (UBOs). The FA values between the groups demonstrated statistically significant differences (P ≤ 0.05) for the cerebellum and thalamus in patients with NF1, independent of the occurrence of UBOs. Diffusion tensor MR imaging confirms the influence of UBOs in the decrease of FA values in this series of patients with NF1. Additionally, this technique allows the characterization of microstructural abnormalities even in some brain regions that appear normal in conventional MR sequences. (orig.)

  1. Comparison of quality control software tools for diffusion tensor imaging.

    Science.gov (United States)

    Liu, Bilan; Zhu, Tong; Zhong, Jianhui

    2015-04-01

    Image quality of diffusion tensor imaging (DTI) is critical for image interpretation, diagnostic accuracy and efficiency. However, DTI is susceptible to numerous detrimental artifacts that may impair the reliability and validity of the obtained data. Although many quality control (QC) software tools are being developed and are widely used and each has its different tradeoffs, there is still no general agreement on an image quality control routine for DTIs, and the practical impact of these tradeoffs is not well studied. An objective comparison that identifies the pros and cons of each of the QC tools will be helpful for the users to make the best choice among tools for specific DTI applications. This study aims to quantitatively compare the effectiveness of three popular QC tools including DTI studio (Johns Hopkins University), DTIprep (University of North Carolina at Chapel Hill, University of Iowa and University of Utah) and TORTOISE (National Institute of Health). Both synthetic and in vivo human brain data were used to quantify adverse effects of major DTI artifacts to tensor calculation as well as the effectiveness of different QC tools in identifying and correcting these artifacts. The technical basis of each tool was discussed, and the ways in which particular techniques affect the output of each of the tools were analyzed. The different functions and I/O formats that three QC tools provide for building a general DTI processing pipeline and integration with other popular image processing tools were also discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  2. Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

    International Nuclear Information System (INIS)

    Cakir, Ozgur; Arslan, Arzu; Inan, Nagihan; Anık, Yonca; Sarısoy, Tahsin; Gumustas, Sevtap; Akansel, Gur

    2013-01-01

    Purpose: To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast. Materials and methods: The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm 2 for DWI and b 0 and 1000 s/mm 2 for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses. Results: Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10 −3 mm 2 /s (b 0–1000 s/mm 2 ) and ≤1.12 × 10 −3 mm 2 /s (b 0–1500 s/mm 2 ), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10 −3 mm 2 /s (b 1000 s/mm 2 ), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm 2 and MD with a b value of 0, 1000 s/mm 2 (AUC = 0.82 ± 0.07). Conclusion: ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision

  3. Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions