Introduction Aging is the accumulation of multidimensional deterioration of process- ing of biological, psychological, and social changes with expansion over time （Bowen and Atwood, 2004; Grady, 2012）. Aging-related...Introduction Aging is the accumulation of multidimensional deterioration of process- ing of biological, psychological, and social changes with expansion over time （Bowen and Atwood, 2004; Grady, 2012）. Aging-related changes are typically accompanied by decline in cognitive function, urinary control, sensory-motor function, and gait ability （Bradley et al., 1991; Bowen and Atwood, 2004; Hedden and Gabrieli, 2004; Grady, 2012; Moran et al., 2012）. In addition, a number of studies have suggested changes in brain structure with normal aging, such as decrease in cortical thickness or increase in ventricular width （Blatter et al., 1995; Tang et al., 1997; Uylings and de Brabander, 2002; Preul et al., 2006; Apostolova et al., 2012）. In particular, ventricular enlargement has been suggested as a structural biomarker for normal aging and progression of some illnesses, such as Alzheimer＇s disease （Blatter et al., 1995; Tang et al.,展开更多
Objective To evaluate the usefulness of diffusion tensor MR imaging in brain white matter diseases. Methods A combined conventional and diffusion tensor MRI were obtained from 10 multiple sclerosis ,10 multiple lacuna...Objective To evaluate the usefulness of diffusion tensor MR imaging in brain white matter diseases. Methods A combined conventional and diffusion tensor MRI were obtained from 10 multiple sclerosis ,10 multiple lacunar infarction,3 cysticercosis,1 angiitis ,1 morphinist and 10 healthy control volunteers. After obtaining mean diffusivity (D) and fractional anisotropy images and image coregistration, the correlations of the lesions and the white matter pathways were investigated. D and AI values were measured form four big lesions which can be seen in T2WI and compared to contralateral white matter. Also D and AI value of four different anatomic locations of normal appearing white matter regions were measured in all patients and controls. Results Whereas the lesions of infarction, cysticercosis and angiitis were in and outside the white matter pathways, all plaques of multiple sclerosis were inside the whit matter pathways. The brain white matter lesions by 1 morphinist were beside the lateral ventricle with big patchy appearance, which was partly inside white matter. For MS, D value was higher in lesions than control white matter. But for other diseases, D value could be seen higher or lower compared to healthy side. AI values were lower in all lesions. D value was higher and AI was lower in normal appearing brain white matter when comparing MS to other cases or healthy control volunteers. Conclusion Diffusion tensor MR images can determine the correlations of the lesions and brain white matter pathways. The changes of D and AI values can improve specificity in differential diagnoses though quantitatively analyzing the tissue damage in lesions and normal appearing brain white matter.展开更多
Traumatic axonal injury is a progressive process evoked by shear forces on the brain, gradually evolving from focal axonal alteration and cumulating in neural disconnection. Clinical classifiers and conventional neuro...Traumatic axonal injury is a progressive process evoked by shear forces on the brain, gradually evolving from focal axonal alteration and cumulating in neural disconnection. Clinical classifiers and conventional neuroimaging are limited in traumatic axonal injury detection, outcome prediction, and treatment guidance. Diffusion weighted imaging is an advanced magnetic resonance imaging (MRI) technique that is sensitive to the movement of water molecules, providing additional information on the micro-structural arrangement of tissue. Quantitative analysis of diffusion metrics can aid in the localization of axonal injury and/or de(dys)myelination caused by trauma. Diffusion MRI tractography is an extension of diffusion weighted imaging, and can provide additional information about white matter pathways and the integrity of brain neural networks. Both techniques are able to detect the early micro-structural changes caused by Traumatic Brain Injury (TBI), and can be used to increase understanding of the mechanisms of brain plasticity in recovery after brain injury and possibly optimize treatment planning of patients with Traumatic Brain Injury. This review focuses on the theoretical basis and applied advanced techniques of diffusion weighted imaging, their limitations and applications, and future directions in the application to TBI.展开更多
Diffusion-tensor imaging can be used to observe the microstructure of brain tissue. Fractional ani- sotropy reflects the integrity of white matter fibers. Fractional anisotropy of a young adult brain is low in gray ma...Diffusion-tensor imaging can be used to observe the microstructure of brain tissue. Fractional ani- sotropy reflects the integrity of white matter fibers. Fractional anisotropy of a young adult brain is low in gray matter, high in white matter, and highest in the splenium of the corpus callosum. Thus, we selected the anterior and posterior limbs of the internal capsule, head of the caudate nucleus, semioval center, thalamus, and corpus callosum （splenium and genu） as regions of interest when using diffusion-tensor imaging to observe fractional anisotropy of major white matter fiber tracts and the deep gray matter of healthy rhesus monkeys aged 4-8 years. Results showed no laterality dif- ferences in fractional anisotropy values. Fractional anisotropy values were low in the head of cau- date nucleus and thalamus in gray matter. Fractional anisotropy values were highest in the sple- nium of corpus callosum in the white matter, followed by genu of the corpus callosum and the pos- terior limb of the internal capsule. Fractional anisotropy values were lowest in the semioval center and posterior limb of internal capsule. These results suggest that fractional anisotropy values in major white matter fibers and the deep gray matter of 4-8-year-old rhesus monkeys are similar to those of healthy young people.展开更多
With improvements in care of at-risk neonates, more and more children survive. This makes it increasingly important to assess, soon after birth, the prognosis of children with hypoxic-ischemic encephalopathy. Computed...With improvements in care of at-risk neonates, more and more children survive. This makes it increasingly important to assess, soon after birth, the prognosis of children with hypoxic-ischemic encephalopathy. Computed tomography, ultrasound, and conventional magnetic resonance imaging are helpful to diagnose brain injury, but cannot quantify white matter damage. In this study, ten full-term infants without brain injury and twenty-two full-term neonates with hypoxic-ischemic encephalopathy （14 moderate cases and 8 severe cases） underwent diffusion tensor imaging to assess its feasibility in evaluating white matter damage in this condition. Results demonstrated that fractional anisotropy, voxel volume, and number of fiber bundles were different in some brain areas between infants with brain injury and those without brain injury. The correlation between fractional anisotropy values and neonatal behavioral neurological assessment scores was closest in the posterior limbs of the internal capsule. We conclude that diffusion tensor imaging can quantify white matter injury in neonates with hypoxic-ischemic encephalopathy.展开更多
We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. ...We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. We analyzed the correlation between fractional anisotropy values and changes in whole-brain gray matter volume. The participants included 20 patients with relapsing-remitting multiple sclerosis and 20 healthy volunteers as controls. All subjects underwent head magnetic resonance imaging and diffusion tensor imaging. Our results revealed that fractional anisotropy values decreased and gray matter volumes were reduced in the genu and splenium of corpus callosum, left anterior thalamic radiation, hippocampus, uncinate fasciculus, right corticospinal tract, bilateral cingulate gyri, and inferior longitudinal fasciculus in multiple sclerosis patients. Gray matter volumes were significantly different between the two groups in the right frontal lobe（superior frontal, middle frontal, precentral, and orbital gyri）, right parietal lobe（postcentral and inferior parietal gyri）, right temporal lobe（caudate nucleus）, right occipital lobe（middle occipital gyrus）, right insula, right parahippocampal gyrus, and left cingulate gyrus. The voxel sizes of atrophic gray matter positively correlated with fractional anisotropy values in white matter association fibers in the patient group. These findings suggest that white matter fiber bundles are extensively injured in multiple sclerosis patients. The main areas of gray matter atrophy in multiple sclerosis are the frontal lobe, parietal lobe, caudate nucleus, parahippocampal gyrus, and cingulate gyrus. Gray matter atrophy is strongly associated with white matter injury in multiple sclerosis patients, particularly with injury to association fibers.展开更多
Efficient strategies for neuroprotection and repair are still an unmet medical need for neurodegenerative diseases and lesions of the central nervous system.Over the last few decades,a great deal of attention has been...Efficient strategies for neuroprotection and repair are still an unmet medical need for neurodegenerative diseases and lesions of the central nervous system.Over the last few decades,a great deal of attention has been focused on white matter as a potential therapeutic target,mainly due to the discovery of the oligodendrocyte precursor cells in the adult central nervous system,a cell type able to fully repair myelin damage,and to the development of advanced imaging techniques to visualize and measure white matter lesions.The combination of these two events has greatly increased the body of research into white matter alte rations in central nervous system lesions and neurodegenerative diseases and has identified the oligodendrocyte precursor cell as a putative target for white matter lesion repair,thus indirectly contributing to neuroprotection.This review aims to discuss the potential of white matter as a therapeutic target for neuroprotection in lesions and diseases of the central nervous system.Pivot conditions are discussed,specifically multiple scle rosis as a white matter disease;spinal cord injury,the acute lesion of a central nervous system component where white matter prevails over the gray matte r,and Alzheimer's disease,where the white matter was considered an ancilla ry component until recently.We first describe oligodendrocyte precursor cell biology and developmental myelination,and its regulation by thyroid hormones,then briefly describe white matter imaging techniques,which are providing information on white matter involvement in central nervous system lesions and degenerative diseases.Finally,we discuss pathological mechanisms which interfere with myelin repair in adulthood.展开更多
Patients with concussion often present with temporary disturbance of consciousness. The microstructural and functional changes in the brain associated with concussion, as well as the relationship with transient cognit...Patients with concussion often present with temporary disturbance of consciousness. The microstructural and functional changes in the brain associated with concussion, as well as the relationship with transient cognitive disorders, are currently unclear. In the present study, a rabbit model of simple concussion was established. Magnetic resonance-diffusion tensor imaging results revealed that the corona radiata and midbrain exhibited significantly decreased fractional anisotropy values in the neural pathways associated with memory and the reticular formation. In addition, the apparent diffusion coefficient values were significantly increased following injury compared with those before injury. Following a 1-hour period of quiet rest, the fractional anisotropy values significantly increased, and apparent diffusion coefficient values significantly decreased, returning to normal pre-injury levels. In contrast, the fractional anisotropy values and apparent diffusion coefficient values in the corpus callosum, thalamus and hippocampus showed no statistical significant alterations following injury. These findings indicate that the neural pathways associated with memory and the reticular formation pathway exhibit reversible microstructural white matter changes when concussion occurs, and these changes are exhibited to a different extent in different regions.展开更多
基金supported by Basic Science Research Program through the National Research Foundation of Korea (NRF)funded by the Ministry of Education, Science and Technology, No. 2012R1A1B4003477
文摘Introduction Aging is the accumulation of multidimensional deterioration of process- ing of biological, psychological, and social changes with expansion over time （Bowen and Atwood, 2004; Grady, 2012）. Aging-related changes are typically accompanied by decline in cognitive function, urinary control, sensory-motor function, and gait ability （Bradley et al., 1991; Bowen and Atwood, 2004; Hedden and Gabrieli, 2004; Grady, 2012; Moran et al., 2012）. In addition, a number of studies have suggested changes in brain structure with normal aging, such as decrease in cortical thickness or increase in ventricular width （Blatter et al., 1995; Tang et al., 1997; Uylings and de Brabander, 2002; Preul et al., 2006; Apostolova et al., 2012）. In particular, ventricular enlargement has been suggested as a structural biomarker for normal aging and progression of some illnesses, such as Alzheimer＇s disease （Blatter et al., 1995; Tang et al.,
文摘Objective To evaluate the usefulness of diffusion tensor MR imaging in brain white matter diseases. Methods A combined conventional and diffusion tensor MRI were obtained from 10 multiple sclerosis ,10 multiple lacunar infarction,3 cysticercosis,1 angiitis ,1 morphinist and 10 healthy control volunteers. After obtaining mean diffusivity (D) and fractional anisotropy images and image coregistration, the correlations of the lesions and the white matter pathways were investigated. D and AI values were measured form four big lesions which can be seen in T2WI and compared to contralateral white matter. Also D and AI value of four different anatomic locations of normal appearing white matter regions were measured in all patients and controls. Results Whereas the lesions of infarction, cysticercosis and angiitis were in and outside the white matter pathways, all plaques of multiple sclerosis were inside the whit matter pathways. The brain white matter lesions by 1 morphinist were beside the lateral ventricle with big patchy appearance, which was partly inside white matter. For MS, D value was higher in lesions than control white matter. But for other diseases, D value could be seen higher or lower compared to healthy side. AI values were lower in all lesions. D value was higher and AI was lower in normal appearing brain white matter when comparing MS to other cases or healthy control volunteers. Conclusion Diffusion tensor MR images can determine the correlations of the lesions and brain white matter pathways. The changes of D and AI values can improve specificity in differential diagnoses though quantitatively analyzing the tissue damage in lesions and normal appearing brain white matter.
文摘Traumatic axonal injury is a progressive process evoked by shear forces on the brain, gradually evolving from focal axonal alteration and cumulating in neural disconnection. Clinical classifiers and conventional neuroimaging are limited in traumatic axonal injury detection, outcome prediction, and treatment guidance. Diffusion weighted imaging is an advanced magnetic resonance imaging (MRI) technique that is sensitive to the movement of water molecules, providing additional information on the micro-structural arrangement of tissue. Quantitative analysis of diffusion metrics can aid in the localization of axonal injury and/or de(dys)myelination caused by trauma. Diffusion MRI tractography is an extension of diffusion weighted imaging, and can provide additional information about white matter pathways and the integrity of brain neural networks. Both techniques are able to detect the early micro-structural changes caused by Traumatic Brain Injury (TBI), and can be used to increase understanding of the mechanisms of brain plasticity in recovery after brain injury and possibly optimize treatment planning of patients with Traumatic Brain Injury. This review focuses on the theoretical basis and applied advanced techniques of diffusion weighted imaging, their limitations and applications, and future directions in the application to TBI.
基金supported by the National Natural Science Foundation of China,No.30960398,81260213the Forty-Seventh Batch of China Postdoctoral Science Foundation,No.20100470376
文摘Diffusion-tensor imaging can be used to observe the microstructure of brain tissue. Fractional ani- sotropy reflects the integrity of white matter fibers. Fractional anisotropy of a young adult brain is low in gray matter, high in white matter, and highest in the splenium of the corpus callosum. Thus, we selected the anterior and posterior limbs of the internal capsule, head of the caudate nucleus, semioval center, thalamus, and corpus callosum （splenium and genu） as regions of interest when using diffusion-tensor imaging to observe fractional anisotropy of major white matter fiber tracts and the deep gray matter of healthy rhesus monkeys aged 4-8 years. Results showed no laterality dif- ferences in fractional anisotropy values. Fractional anisotropy values were low in the head of cau- date nucleus and thalamus in gray matter. Fractional anisotropy values were highest in the sple- nium of corpus callosum in the white matter, followed by genu of the corpus callosum and the pos- terior limb of the internal capsule. Fractional anisotropy values were lowest in the semioval center and posterior limb of internal capsule. These results suggest that fractional anisotropy values in major white matter fibers and the deep gray matter of 4-8-year-old rhesus monkeys are similar to those of healthy young people.
基金supported by a grant from the Clinical Medicine Science and Technology Projects in Jiangsu Province of China,No.BL2014037a grant from the Changzhou City Science and Technology Support Plan in China,No.CE20165027+1 种基金a grant from the Changzhou Health Development Planning Commission Major Projects in China,No.ZD201515the Changzhou High-Level Health Personnel Training Project Funding
文摘With improvements in care of at-risk neonates, more and more children survive. This makes it increasingly important to assess, soon after birth, the prognosis of children with hypoxic-ischemic encephalopathy. Computed tomography, ultrasound, and conventional magnetic resonance imaging are helpful to diagnose brain injury, but cannot quantify white matter damage. In this study, ten full-term infants without brain injury and twenty-two full-term neonates with hypoxic-ischemic encephalopathy （14 moderate cases and 8 severe cases） underwent diffusion tensor imaging to assess its feasibility in evaluating white matter damage in this condition. Results demonstrated that fractional anisotropy, voxel volume, and number of fiber bundles were different in some brain areas between infants with brain injury and those without brain injury. The correlation between fractional anisotropy values and neonatal behavioral neurological assessment scores was closest in the posterior limbs of the internal capsule. We conclude that diffusion tensor imaging can quantify white matter injury in neonates with hypoxic-ischemic encephalopathy.
基金supported by the Project of Science and Technology Department of Jilin Province in China,No.20160101023JC
文摘We observed the characteristics of white matter fibers and gray matter in multiple sclerosis patients, to identify changes in diffusion tensor imaging fractional anisotropy values following white matter fiber injury. We analyzed the correlation between fractional anisotropy values and changes in whole-brain gray matter volume. The participants included 20 patients with relapsing-remitting multiple sclerosis and 20 healthy volunteers as controls. All subjects underwent head magnetic resonance imaging and diffusion tensor imaging. Our results revealed that fractional anisotropy values decreased and gray matter volumes were reduced in the genu and splenium of corpus callosum, left anterior thalamic radiation, hippocampus, uncinate fasciculus, right corticospinal tract, bilateral cingulate gyri, and inferior longitudinal fasciculus in multiple sclerosis patients. Gray matter volumes were significantly different between the two groups in the right frontal lobe（superior frontal, middle frontal, precentral, and orbital gyri）, right parietal lobe（postcentral and inferior parietal gyri）, right temporal lobe（caudate nucleus）, right occipital lobe（middle occipital gyrus）, right insula, right parahippocampal gyrus, and left cingulate gyrus. The voxel sizes of atrophic gray matter positively correlated with fractional anisotropy values in white matter association fibers in the patient group. These findings suggest that white matter fiber bundles are extensively injured in multiple sclerosis patients. The main areas of gray matter atrophy in multiple sclerosis are the frontal lobe, parietal lobe, caudate nucleus, parahippocampal gyrus, and cingulate gyrus. Gray matter atrophy is strongly associated with white matter injury in multiple sclerosis patients, particularly with injury to association fibers.
文摘Efficient strategies for neuroprotection and repair are still an unmet medical need for neurodegenerative diseases and lesions of the central nervous system.Over the last few decades,a great deal of attention has been focused on white matter as a potential therapeutic target,mainly due to the discovery of the oligodendrocyte precursor cells in the adult central nervous system,a cell type able to fully repair myelin damage,and to the development of advanced imaging techniques to visualize and measure white matter lesions.The combination of these two events has greatly increased the body of research into white matter alte rations in central nervous system lesions and neurodegenerative diseases and has identified the oligodendrocyte precursor cell as a putative target for white matter lesion repair,thus indirectly contributing to neuroprotection.This review aims to discuss the potential of white matter as a therapeutic target for neuroprotection in lesions and diseases of the central nervous system.Pivot conditions are discussed,specifically multiple scle rosis as a white matter disease;spinal cord injury,the acute lesion of a central nervous system component where white matter prevails over the gray matte r,and Alzheimer's disease,where the white matter was considered an ancilla ry component until recently.We first describe oligodendrocyte precursor cell biology and developmental myelination,and its regulation by thyroid hormones,then briefly describe white matter imaging techniques,which are providing information on white matter involvement in central nervous system lesions and degenerative diseases.Finally,we discuss pathological mechanisms which interfere with myelin repair in adulthood.
基金supported by the Military Medical Science and Technology Research During the Eleventh Five-Year Plan, No. 06MA96
文摘Patients with concussion often present with temporary disturbance of consciousness. The microstructural and functional changes in the brain associated with concussion, as well as the relationship with transient cognitive disorders, are currently unclear. In the present study, a rabbit model of simple concussion was established. Magnetic resonance-diffusion tensor imaging results revealed that the corona radiata and midbrain exhibited significantly decreased fractional anisotropy values in the neural pathways associated with memory and the reticular formation. In addition, the apparent diffusion coefficient values were significantly increased following injury compared with those before injury. Following a 1-hour period of quiet rest, the fractional anisotropy values significantly increased, and apparent diffusion coefficient values significantly decreased, returning to normal pre-injury levels. In contrast, the fractional anisotropy values and apparent diffusion coefficient values in the corpus callosum, thalamus and hippocampus showed no statistical significant alterations following injury. These findings indicate that the neural pathways associated with memory and the reticular formation pathway exhibit reversible microstructural white matter changes when concussion occurs, and these changes are exhibited to a different extent in different regions.
