The Experts below are selected from a list of 42324 Experts worldwide ranked by ideXlab platform

David M. Greer - One of the best experts on this subject based on the ideXlab platform.

Susumu Mori - One of the best experts on this subject based on the ideXlab platform.

  • structural insights into the rodent cns via Diffusion Tensor Imaging
    Trends in Neurosciences, 2012
    Co-Authors: Jiangyang Zhang, Susumu Mori, Manisha Aggarwal
    Abstract:

    Diffusion Tensor Imaging (DTI) is a useful tool for studying anatomy and pathology in the rodent central nervous system (CNS).The unique tissue contrasts provided by DTI are well suited for monitoring disease progression, studying brain development, and characterizing anatomical phenotypes. Recent technical developments have vastly improved the speed and resolution of rodent DTI. Ongoing research efforts exploring the microstructural basis of DTI signals have provided useful insights into its capabilities to delineate brain structures and detect neuropathology. Significant progress has also been made in combining DTI results with data acquired using other Imaging modalities to enhance our understanding of the rodent CNS.

  • Diffusion Tensor Imaging of cingulum fibers in mild cognitive impairment and alzheimer disease
    Neurology, 2007
    Co-Authors: Yu Zhang, Susumu Mori, Norbert Schuff, Geonho Jahng, W Bayne, Lothar R Schad, Susanne G Mueller, Joel H Kramer, Kristine Yaffe, Helena C Chui
    Abstract:

    Background: NeuroImaging in mild cognitive impairment (MCI) and Alzheimer disease (AD) generally shows medial temporal lobe atrophy and diminished glucose metabolism and cerebral blood flow in the posterior cingulate gyrus. However, it is unclear whether these abnormalities also impact the cingulum fibers, which connect the medial temporal lobe and the posterior cingulate regions. Objective: To use Diffusion Tensor Imaging (DTI), by measuring fractional anisotropy (FA), to test 1) if MCI and AD are associated with DTI abnormalities in the parahippocampal and posterior cingulate regions of the cingulum fibers; 2) if white matter abnormalities extend to the neocortical fiber connections in the corpus callosum (CC); 3) if DTI improves accuracy to separate AD and MCI from healthy aging vs structural MRI. Methods: DTI and structural MRI were preformed on 17 patients with AD, 17 with MCI, and 18 cognitively normal (CN) subjects. Results: FA of the cingulum fibers was significantly reduced in MCI, and even more in AD. FA was also significantly reduced in the splenium of the CC in AD, but not in MCI. Adding DTI to hippocampal volume significantly improved the accuracy to separate MCI and AD from CN. Conclusion: Assessment of the cingulum fibers using Diffusion Tensor Imaging may aid early diagnosis of Alzheimer disease.

  • Diffusion Tensor Imaging of periventricular leukomalacia shows affected sensory cortex white matter pathways
    Neurology, 2002
    Co-Authors: Alexander H Hoon, W T Lawrie, Elias R Melhem, Elsie M Reinhardt, Meiyappan Solaiyappan, Hangyi Jiang, Michael V. Johnston, Peter C.m. Van Zijl, Susumu Mori
    Abstract:

    The authors used Diffusion-Tensor Imaging to examine central white matter pathways in two children with spastic quadriplegic cerebral palsy. Corticospinal tracts projecting from cortex to brainstem resembled controls. In contrast, posterior regions of the corpus callosum, internal capsule, and corona radiata were markedly reduced, primarily in white matter fibers connected to sensory cortex. These findings suggest that the motor impairment in periventricular leukomalacia may, in part, reflect disruption of sensory connections outside classic pyramidal motor pathways.

  • mr Diffusion Tensor Imaging documented arcuate fasciculus lesion in a patient with normal repetition performance
    Aphasiology, 2002
    Co-Authors: Ola A Selnes, Argye E Hillis, Peter C M Van Zijl, Peter B Barker, Susumu Mori
    Abstract:

    Background: The pathophysiology of the syndrome of conduction aphasia has been thought to involve a disconnection between posterior and anterior language areas. The arcuate fasciculus has been one of the principal candidates for an anatomical link between Wernicke's and Broca's area, but direct evidence for its involvement in conduction aphasia has been difficult to obtain. Aims: The purpose of this study was to examine white matter tract integrity, using the novel magnetic resonance Imaging technique of Diffusion Tensor Imaging, in a patient with transcortical aphasia. Methods & Procedures: A case study of a 55-year-old, right-handed man with aphasia following a left hemisphere stroke is reported. The patient's language performance was assessed with the Boston Diagnostic Aphasia Examination twice: at 10 days and at 2 years after his stroke. An MR Diffusion Tensor Imaging study was obtained approximately 2 years after his stroke using the 1.5 T Phillips Gyroscan NT system. White matter fibre tracts maps w...

  • high resolution isotropic 3d Diffusion Tensor Imaging of the human brain
    Magnetic Resonance in Medicine, 2002
    Co-Authors: Hangyi Jiang, Susumu Mori, Peter C.m. Van Zijl, Xavier Golay
    Abstract:

    High-resolution cardiac-gated 3D Diffusion Tensor Imaging (3D-DTI) is demonstrated in vivo for several areas of the human brain. Anatomical mapping of subcortical white matter (WM), as well as definition and identification of major WM bundles from the brainstem were performed in humans for the first time using this technique. Improved intrinsic signal-to-noise ratio (SNR) and relatively reduced sensitivity to physiological motion (e.g., brain pulsations) with respect to cardiac-gated multislice acquisition are demonstrated. The advantages and weaknesses of this approach are discussed.

Jürgen Finsterbusch - One of the best experts on this subject based on the ideXlab platform.

  • Diffusion Tensor Imaging Assessment of Regional White Matter Changes in the Cervical and Thoracic Spinal Cord in Pediatric Subjects
    Journal of neurotrauma, 2018
    Co-Authors: Sona Saksena, Feroze B. Mohamed, Devon M. Middleton, Laura Krisa, Alizadeh, Shiva Shahrampour, Chris J. Conklin, Adam E. Flanders, Jürgen Finsterbusch, Mary Jane Mulcahey
    Abstract:

    Abstract There are no studies to date,describing changes in the Diffusion Tensor Imaging (DTI) metrics of the white matter (WM) regions of the entire cervical and thoracic spinal cord (SC) remote f...

  • high resolution Diffusion Tensor Imaging with inner field of view epi
    Journal of Magnetic Resonance Imaging, 2009
    Co-Authors: Jürgen Finsterbusch
    Abstract:

    Purpose To demonstrate the applicability of inner field-of-view (FOV) echo-planar Imaging based on spatially two-dimensional selective radiofrequency excitations to high-resolution Diffusion Tensor Imaging. Materials and Methods Diffusion Tensor Imaging of inner FOVs with in-plane resolutions of 0.90 × 0.90 mm2 and 0.50 × 0.50 mm2 was performed in the human brain and cervical spinal cord on a 3 T whole-body MR system. Results Using inner FOVs reduces geometric distortions in echo-planar Imaging and allows for an improved in-plane resolution. Some of the crossings of transverse pontine fibers with the pyramidal tracts in the brainstem could be resolved, increased Diffusion anisotropy and fiber orientation could be identified in cerebellar white matter, and the reduced Diffusion anisotropy of spinal cord gray matter could be detected. Conclusion Inner FOV echo-planar Imaging may help to improve the spatial resolution and thus the accuracy of Diffusion anisotropy and white matter fiber orientation measurements in the human central nervous system. J. Magn. Reson. Imaging 2009;29:987–993. © 2009 Wiley-Liss, Inc.

Ahmed Abdel Khalek Abdel Razek - One of the best experts on this subject based on the ideXlab platform.

  • Diffusion Tensor Imaging of the lateral rectus muscle in duane retraction syndrome
    Journal of Computer Assisted Tomography, 2019
    Co-Authors: Ahmed Abdel Khalek Abdel Razek, Eman Helmy, Hala Maher, Manal Ali Kasem
    Abstract:

    AIM This study aimed to assess metrics of Diffusion Tensor Imaging in evaluating microstructural abnormalities of the lateral rectus muscle in Duane retraction syndrome (DRS). PATIENT AND METHODS A prospective study was conducted on 27 patients with DRS and 16 age- and sex-matched controls who underwent Diffusion Tensor Imaging of orbit and forced duction test (FDT). Fractional anisotropy (FA) and mean diffusivity (MD) of the lateral rectus were calculated by 2 observers. RESULTS Fractional anisotropy of the lateral rectus in patients (0.62 ± 0.07 and 0.59 ± 0.06) was significantly higher (P = 0.001) than that in controls (0.49 ± 0.06 and 0.51 ± 0.06). Selection values of 0.53 and 0.52 as cutoff points of FA of the lateral rectus to differentiate patients from controls revealed areas under the curve of 0.92 and 0.86 and accuracy values of 84.8% and 80.4% by both observers, respectively. Mean diffusivity of the lateral rectus by both observers in patients (1.19 ± 0.13 and 1.23 ± 0.19 × 10 mm/s) was significantly lower (P = 0.001) than that in controls (1.54 ± 0.18 and 1.49 ± 0.16 × 10 mm/s). Selection values of 1.35 and 1.40 × 10 mm/s as cutoff points of MD of the lateral rectus to differentiate patients from the control groups revealed areas under the curve of 0.93 and 0.85 and accuracy values of 91.3% and 80.4% by both observers, respectively. Interobserver agreement for MD and FA of the lateral rectus by both observers were excellent (r = 0.870 and, 0.959). Diffusion Tensor Imaging metrics of the lateral rectus muscle did not differ significantly between patients with unilateral and bilateral disease (P = 0.05) and patients with DRS type I and type III (P = 0.05). Diffusion Tensor Imaging metrics of the lateral rectus muscle differed significantly between FDT grades I and II versus grades III and IV, and these metrics were well correlated with the degree of FDT. CONCLUSION Diffusion Tensor Imaging metrics are valuable noninvasive tools in evaluating the microstructural abnormalities of the lateral rectus in DRS and are well correlated with degree of FDT.

  • Diffusion Tensor Imaging of the optic disc in idiopathic intracranial hypertension
    Neuroradiology, 2018
    Co-Authors: Ahmed Abdel Khalek Abdel Razek, Nihal M Batouty, Wesam Fathy, Rania Bassiouny
    Abstract:

    To study optic disc in idiopathic intracranial hypertension (IIH) with Diffusion Tensor Imaging. Prospective study was carried out on 31 consecutive patients with IIH and 17 age and sex-matched controls that underwent Diffusion Tensor Imaging of optic nerve. Fractional anisotropy (FA) and mean diffusivity (MD) of optic disc were measured by two readers. Grades of papilledema and visual field defects were evaluated by ophthalmologist. FA of optic disc was significantly lower in IIH than controls (p = 0.001) with excellent inter-observer agreement (K = 0.93) of both readers. The cutoff FA used to differentiating IIH from controls were 0.28 and 0.29 with area under curve (AUC) of 0.921 and 0.914, accuracy 92% and 91%, and sensitivity 97% and 96%. MD of optic disc were significantly higher in IIH than in controls (p = 0.001) with excellent inter-observer agreement (K = 0.91) of both readers. The cutoff MD used to differentiating IIH from controls was 1.51 and 1.22 × 10−3 mm2/s with AUC 0.943 and 0.922, and accuracy 94% and 92% respectively. FA of optic disc was significantly lower in early than advanced papilledema and visual field defects (p = 0.001, 0.001) respectively. The MD of optic disc was significantly higher in early than advanced papilledema and visual field defects (p = 0.001, 0.001) respectively. Diffusion Tensor Imaging parameters of optic disc are non-invasive reliable Imaging parameters that can be used for diagnosis of IIH and well correlated with papilledema and visual field defects.

  • Diffusion Tensor Imaging of the optic disc in idiopathic intracranial hypertension
    Neuroradiology, 2018
    Co-Authors: Ahmed Abdel Khalek Abdel Razek, Nihal M Batouty, Wesam Fathy, Rania Bassiouny
    Abstract:

    PURPOSE: To study optic disc in idiopathic intracranial hypertension (IIH) with Diffusion Tensor Imaging. METHODS: Prospective study was carried out on 31 consecutive patients with IIH and 17 age and sex-matched controls that underwent Diffusion Tensor Imaging of optic nerve. Fractional anisotropy (FA) and mean diffusivity (MD) of optic disc were measured by two readers. Grades of papilledema and visual field defects were evaluated by ophthalmologist. RESULTS: FA of optic disc was significantly lower in IIH than controls (p = 0.001) with excellent inter-observer agreement (K = 0.93) of both readers. The cutoff FA used to differentiating IIH from controls were 0.28 and 0.29 with area under curve (AUC) of 0.921 and 0.914, accuracy 92% and 91%, and sensitivity 97% and 96%. MD of optic disc were significantly higher in IIH than in controls (p = 0.001) with excellent inter-observer agreement (K = 0.91) of both readers. The cutoff MD used to differentiating IIH from controls was 1.51 and 1.22 × 10-3 mm2/s with AUC 0.943 and 0.922, and accuracy 94% and 92% respectively. FA of optic disc was significantly lower in early than advanced papilledema and visual field defects (p = 0.001, 0.001) respectively. The MD of optic disc was significantly higher in early than advanced papilledema and visual field defects (p = 0.001, 0.001) respectively. CONCLUSION: Diffusion Tensor Imaging parameters of optic disc are non-invasive reliable Imaging parameters that can be used for diagnosis of IIH and well correlated with papilledema and visual field defects.

  • Diffusion Tensor Imaging of mild moderate carpal tunnel syndrome correlation with nerve conduction study and clinical tests
    Clinical Rheumatology, 2017
    Co-Authors: Ahmed Abdel Khalek Abdel Razek, Adel A Shabana, Tamer Omar El Saied, Nora Alrefey
    Abstract:

    The purpose of this study was to assess Diffusion Tensor Imaging in the diagnosis of mild-moderate carpal tunnel syndrome (CTS) and to correlate fractional anisotropy (FA) and apparent Diffusion coefficient (ADC) with nerve conduction study and clinical tests. This prospective study was conducted upon 39 patients (9 males, 30 females; mean age = 33 years) with early stage of CTS. Twenty age- and sex-matched healthy volunteers were included as a control group. All patients underwent clinical tests and nerve conduction studies with calculation of the distal motor latency (DML) and distal sensory latency (DSL). Patients with CTS and volunteers underwent Diffusion Tensor Imaging of the median nerve. The cross-sectional area (CSA), FA, and ADC of the median nerve were calculated. There was significant difference in FA and ADC between patients and controls (P = 0.001 respectively) and between mild and moderate CTS (P = 0.001 respectively). The cutoff FA and ADC of the median nerve used for the diagnosis of CTS were 0.45 and 1.31 × 10−3 mm2/s with areas under the curve (AUC) of 0.985 and 0.954, respectively, and the values used to differentiate mild from moderate CTS were 0.42 and 1.35 × 10−3 mm2/s with AUC of 0.964 and 0.688, respectively. The FA and ADC of the median nerve were correlated with CSA (r = 0.894; −0.769), DML (r = −0.935; 0.781), DSL (r = −0.953; 0.781), Tinel’s test (r = 0.742; 0.684), and Phalen’s test (r = 0.862; 0.742). Diffusion Tensor Imaging can be used for the diagnosis of mild-moderate CTS and well correlated with nerve conduction studies and clinical tests.

  • Diffusion Tensor Imaging of the renal cortex in diabetic patients correlation with urinary and serum biomarkers
    Abdominal Radiology, 2017
    Co-Authors: Ahmed Abdel Khalek Abdel Razek, Mohammad Alsayed Abd Alhamid Aladlany, Alhadidy Mohammed Alhadidy, Mohammed Ali Atwa, Naglaa Elsayed Abass Abdou
    Abstract:

    Purpose To demonstrate role of Diffusion Tensor Imaging of the kidney in diabetic patients and to correlate renal fractional anisotropy (FA) and apparent Diffusion coefficient (ADC) of the renal cortex with urinary and serum biomarkers of diabetes.

Adolf Pfefferbaum - One of the best experts on this subject based on the ideXlab platform.

  • mr Diffusion Tensor Imaging a window into white matter integrity of the working brain
    Neuropsychology Review, 2010
    Co-Authors: Edith V Sullivan, Adolf Pfefferbaum, Sandra Chanraud, Natalie M Zahr
    Abstract:

    As Norman Geschwind asserted in 1965, syndromes resulting from white matter lesions could produce deficits in higher-order functions and “disconnexion” or the interruption of connection between gray matter regions could be as disruptive as trauma to those regions per se. The advent of in vivo Diffusion Tensor Imaging, which allows quantitative characterization of white matter fiber integrity in health and disease, has served to strengthen Geschwind’s proposal. Here we present an overview of the principles of Diffusion Tensor Imaging (DTI) and its contribution to progress in our current understanding of normal and pathological brain function.

  • Diffusion Tensor Imaging and aging
    Neuroscience & Biobehavioral Reviews, 2006
    Co-Authors: Edith V Sullivan, Adolf Pfefferbaum
    Abstract:

    Magnetic resonance Diffusion Tensor Imaging (DTI) is a non-invasive in vivo method for characterizing the integrity of anatomical connections and white matter circuitry and provides a quantitative assessment of the brain's white matter microstructure. DTI studies reveal age-related declines in white matter fractional ansiotropy (FA) in normal healthy adults in whom volume declines are not necessarily detectable. The decline is equivalent in men and women, is linear from about age 20 years onwards, and has a frontal distribution. Studies combining regional DTI metrics and tests of specific cognitive and motor functions have shown that age-related declines in white matter integrity are associated with similar declines in interhemispheric transfer, especially dependent on frontal systems. Emerging from recent DTI findings and conceptualizations of neural causes of cognitive decline in aging, we propose three white matter-mediated neural system hypotheses of aging brain structure and function: (1) the anteroposterior gradient, (2) bilateral recruitment of brain systems via the corpus callosum for frontally based task execution, and (3) frontocerebellar synergism. These hypotheses are not mutually exclusive but establish a basis for posing testable questions about brain systems recruited when those used in youth are altered by aging.

  • compromised white matter tract integrity in schizophrenia inferred from Diffusion Tensor Imaging
    Archives of General Psychiatry, 1999
    Co-Authors: Michael E Moseley, Kelvin O Lim, Maj Hedehus, Alexander De Crespigny, Edith V Sullivan, Adolf Pfefferbaum
    Abstract:

    Background Current investigations suggest that brain white matter may be qualitatively altered in schizophrenia even in the face of normal white matter volume. Diffusion Tensor Imaging provides a new approach for quantifying the directional coherence and possibly connectivity of white matter fibers in vivo. Methods Ten men who were veterans of the US Armed Forces and met the DSM-IV criteria for schizophrenia and 10 healthy, age-matched control men were scanned using magnetic resonance Diffusion Tensor Imaging and magnetic resonance structural Imaging. Results Relative to controls, the patients with schizophrenia exhibited lower anisotropy in white matter, despite absence of a white matter volume deficit. In contrast to the white matter pattern, gray matter anisotropy did not distinguish the groups, even though the patients with schizophrenia had a significant gray matter volume deficit. The abnormal white matter anisotropy in patients with schizophrenia was present in both hemispheres and was widespread, extending from the frontal to occipital brain regions. Conclusions Despite the small sample size, Diffusion Tensor Imaging was powerful enough to yield significant group differences, indicating widespread alteration in brain white matter integrity but not necessarily white matter volume in schizophrenia.