During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness...During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness.However,events related to early neuropathological events,neuroinflammation,deterioration of neuronal connectivity and compensatory mechanisms still remain vastly unknown.Ultra-high field diffusion MRI(UHFD-MRI)techniques can contribute to a more comprehensive analysis of the early microstructural changes observed in HD.In addition,it is possible to evaluate if early imaging microstructural parameters might be linked to histological biomarkers.Moreover,qualitative studies analyzing histological complexity in brain areas susceptible to neurodegeneration could provide information on inflammatory events,compensatory increase of neuroconnectivity and mechanisms of brain repair and regeneration.The application of ultra-high field diffusion-MRI technology in animal models,particularly the R6/1 mice(a common preclinical mammalian model of HD),provide the opportunity to analyze alterations in a physiologically intact model of the disease.Although some disparities in volumetric changes across different brain structures between preclinical and clinical models has been documented,further application of different diffusion MRI techniques used in combination like diffusion tensor imaging,and neurite orientation dispersion and density imaging have proved effective in characterizing early parameters associated to alteration in water diffusion exchange within intracellular and extracellular compartments in brain white and grey matter.Thus,the combination of diffusion MRI imaging techniques and more complex neuropathological analysis could accelerate the discovery of new imaging biomarkers and the early diagnosis and neuromonitoring of patients affected with HD.展开更多
Objective: Cell structural changes are one of the main features observed during the development of amyotrophic lateral sclerosis(ALS). In this work, we propose the use of diffusion tensor imaging(DTI) metrics to asses...Objective: Cell structural changes are one of the main features observed during the development of amyotrophic lateral sclerosis(ALS). In this work, we propose the use of diffusion tensor imaging(DTI) metrics to assess specific ultrastructural changes in the central nervous system during the early neurodegenerative stages of ALS.Methods: Ultra-high field MRI and DTI data at 17.6 T were obtained from fixed, excised mouse brains, and spinal cords from ALS(G93 A-SOD1) mice.Results: Changes in fractional anisotropy(FA) and linear, planar, and spherical anisotropy ratios(C_L, C_P, and C_S, respectively) of the diffusion eigenvalues were measured in white matter(WM) and gray matter(GM) areas associated with early axonal degenerative processes(in both the brain and the spinal cord). Specifically, in WM structures(corpus callosum, corticospinal tract, and spinal cord funiculi) as the disease progressed, FA, C_L, and C_P values decreased, whereas C_S values increased. In GM structures(prefrontal cortex, hippocampus, and central spinal cord) FA and C_P decreased, whereas the C_L and C_S values were unchanged or slightly smaller. Histological studies of a fluorescent mice model(YFP, G93 A-SOD1 mouse) corroborated the early alterations in neuronal morphology and axonal connectivity measured by DTI.Conclusions: Changes in diffusion tensor shape were observed in this animal model at the early, nonsymptomatic stages of ALS. Further studies of C_L, C_P, and C_S as imaging biomarkers should be undertaken to refine this neuroimaging tool for future clinical use in the detection of the early stages of ALS.展开更多
Background:Amyotrophic lateral sclerosis(ALS)is a disease characterized by a progressive degeneration of motor neurons leading to paralysis.Our previous MRI diffusion tensor imaging studies detected early white matter...Background:Amyotrophic lateral sclerosis(ALS)is a disease characterized by a progressive degeneration of motor neurons leading to paralysis.Our previous MRI diffusion tensor imaging studies detected early white matter changes in the spinal cords of mice carrying the G93A-SOD1 mutation.Here,we extend those studies using ultra-high field MRI(17.6 T)and fluorescent microscopy to investigate the appearance of early structural and connectivity changes in the spinal cords of ALS mice.Methods:The spinal cords from presymptomatic and symptomatic mice(80 to 120 days of age)were scanned(ex-vivo)using diffusion-weighted MRI.The fractional anisotropy(FA),axial(AD)and radial(RD)diffusivities were calculated for axial slices from the thoracic,cervical and lumbar regions of the spinal cords.The diffusion parameters were compared with fluorescence microscopy and membrane cellular markers from the same tissue regions.Results:At early stages of the disease(day 80)in the lumbar region,we found,a 19% decrease in FA,a 9% decrease in AD and a 35% increase in RD.Similar changes were observed in cervical and thoracic spinal cord regions.Differences between control and ALS mice groups at the symptomatic stages(day 120)were larger.Quantitative fluorescence microscopy at 80 days,demonstrated a 22% reduction in axonal area and a 22% increase in axonal density.Tractography and quantitative connectome analyses measured by edge weights showed a 52%decrease in the lumbar regions of the spinal cords of this ALS mice group.A significant increase in ADC(23.3%)in the ALS mice group was related to an increase in aquaporin markers.Conclusions:These findings suggest that the combination of ultra-high field diffusion MRI with fluorescent ALS mice reporters is a useful approach to detect and characterize presymptomatic white matter micro-ultrastructural changes and axonal connectivity anomalies in ALS.展开更多
Functional brain imaging technology has developed rapidly in recent years.On the one hand,high-field 7-Tesla magnetic resonance imaging(MRI)has excelled the limited spatial resolution of 3-Tesla MRI,allowing us to ent...Functional brain imaging technology has developed rapidly in recent years.On the one hand,high-field 7-Tesla magnetic resonance imaging(MRI)has excelled the limited spatial resolution of 3-Tesla MRI,allowing us to enter a new world of mesoscopic imaging from the macroscopic imaging of human brain functions.On the other hand,novel optical pumping magnetometer-magnetoencephalography(OPM-MEG)has broken down the technical barriers of traditional superconducting MEG,which brings imaging of neuronal electromagnetic signals from cortical imaging to whole-brain imaging.This article aims to present a brief introduction regarding the development of conventional MRI and MEG technology,and,more importantly,to delineate that high-field MRI and OPM-MEG complement each other and together will lead us into a new era of functional brain imaging.展开更多
This paper briefly summarizes the development of magnetic resonance imaging and spectroscopy in medicine.Aspects of magnetic resonancephysics and-technology relevant at ultra-high magnetic fields as well as current li...This paper briefly summarizes the development of magnetic resonance imaging and spectroscopy in medicine.Aspects of magnetic resonancephysics and-technology relevant at ultra-high magnetic fields as well as current limitations are highlighted.Based on the first promising studies,potential clinical applications at 7 Tesla are suggested.Other aims are to stimulate awareness of the potential of ultra-high field magnetic resonance and to stimulate active participation in much needed basic or clinical research at 7 Tesla or higher.展开更多
An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of...An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of temperature field,such as the induction frequency,the dimension of coil and the gap between coil and workpiece,are investigated considering temperature-dependent material properties by using FLUX 2Dsoftware.The temperature field characteristic in ultra-high induction heating is obtained and discussed.The numerical values are compared with the experimental results.A good agreement between them is observed with 7.9% errors.展开更多
基金supported in part by the High Magnetic Field Laboratory(NHMFL)and Advanced Magnetic Resonance Imaging and Spectroscopy(AMRIS)under Magnetic Laboratory Visiting Scientist Program Award,No.VSP#327(to RG)。
文摘During the last decades,advances in the understanding of genetic,cellular,and microstructural alterations associated to Huntington's disease(HD)have improved the understanding of this progressive and fatal illness.However,events related to early neuropathological events,neuroinflammation,deterioration of neuronal connectivity and compensatory mechanisms still remain vastly unknown.Ultra-high field diffusion MRI(UHFD-MRI)techniques can contribute to a more comprehensive analysis of the early microstructural changes observed in HD.In addition,it is possible to evaluate if early imaging microstructural parameters might be linked to histological biomarkers.Moreover,qualitative studies analyzing histological complexity in brain areas susceptible to neurodegeneration could provide information on inflammatory events,compensatory increase of neuroconnectivity and mechanisms of brain repair and regeneration.The application of ultra-high field diffusion-MRI technology in animal models,particularly the R6/1 mice(a common preclinical mammalian model of HD),provide the opportunity to analyze alterations in a physiologically intact model of the disease.Although some disparities in volumetric changes across different brain structures between preclinical and clinical models has been documented,further application of different diffusion MRI techniques used in combination like diffusion tensor imaging,and neurite orientation dispersion and density imaging have proved effective in characterizing early parameters associated to alteration in water diffusion exchange within intracellular and extracellular compartments in brain white and grey matter.Thus,the combination of diffusion MRI imaging techniques and more complex neuropathological analysis could accelerate the discovery of new imaging biomarkers and the early diagnosis and neuromonitoring of patients affected with HD.
基金Magnetic Laboratory Visiting Scientist Program,Grant/Award Number 327Chicago Biomedical Consortium,Grant/Award Number 085740National Science Foundation,Grant/Award Number DMR-1157490。
文摘Objective: Cell structural changes are one of the main features observed during the development of amyotrophic lateral sclerosis(ALS). In this work, we propose the use of diffusion tensor imaging(DTI) metrics to assess specific ultrastructural changes in the central nervous system during the early neurodegenerative stages of ALS.Methods: Ultra-high field MRI and DTI data at 17.6 T were obtained from fixed, excised mouse brains, and spinal cords from ALS(G93 A-SOD1) mice.Results: Changes in fractional anisotropy(FA) and linear, planar, and spherical anisotropy ratios(C_L, C_P, and C_S, respectively) of the diffusion eigenvalues were measured in white matter(WM) and gray matter(GM) areas associated with early axonal degenerative processes(in both the brain and the spinal cord). Specifically, in WM structures(corpus callosum, corticospinal tract, and spinal cord funiculi) as the disease progressed, FA, C_L, and C_P values decreased, whereas C_S values increased. In GM structures(prefrontal cortex, hippocampus, and central spinal cord) FA and C_P decreased, whereas the C_L and C_S values were unchanged or slightly smaller. Histological studies of a fluorescent mice model(YFP, G93 A-SOD1 mouse) corroborated the early alterations in neuronal morphology and axonal connectivity measured by DTI.Conclusions: Changes in diffusion tensor shape were observed in this animal model at the early, nonsymptomatic stages of ALS. Further studies of C_L, C_P, and C_S as imaging biomarkers should be undertaken to refine this neuroimaging tool for future clinical use in the detection of the early stages of ALS.
基金This study was supported in part by a Chicago Biomedical Consortium(CBC)postdoctoral fellowship grant(Award#085740)to RG at the University of Illinois in Chicago.
文摘Background:Amyotrophic lateral sclerosis(ALS)is a disease characterized by a progressive degeneration of motor neurons leading to paralysis.Our previous MRI diffusion tensor imaging studies detected early white matter changes in the spinal cords of mice carrying the G93A-SOD1 mutation.Here,we extend those studies using ultra-high field MRI(17.6 T)and fluorescent microscopy to investigate the appearance of early structural and connectivity changes in the spinal cords of ALS mice.Methods:The spinal cords from presymptomatic and symptomatic mice(80 to 120 days of age)were scanned(ex-vivo)using diffusion-weighted MRI.The fractional anisotropy(FA),axial(AD)and radial(RD)diffusivities were calculated for axial slices from the thoracic,cervical and lumbar regions of the spinal cords.The diffusion parameters were compared with fluorescence microscopy and membrane cellular markers from the same tissue regions.Results:At early stages of the disease(day 80)in the lumbar region,we found,a 19% decrease in FA,a 9% decrease in AD and a 35% increase in RD.Similar changes were observed in cervical and thoracic spinal cord regions.Differences between control and ALS mice groups at the symptomatic stages(day 120)were larger.Quantitative fluorescence microscopy at 80 days,demonstrated a 22% reduction in axonal area and a 22% increase in axonal density.Tractography and quantitative connectome analyses measured by edge weights showed a 52%decrease in the lumbar regions of the spinal cords of this ALS mice group.A significant increase in ADC(23.3%)in the ALS mice group was related to an increase in aquaporin markers.Conclusions:These findings suggest that the combination of ultra-high field diffusion MRI with fluorescent ALS mice reporters is a useful approach to detect and characterize presymptomatic white matter micro-ultrastructural changes and axonal connectivity anomalies in ALS.
文摘Functional brain imaging technology has developed rapidly in recent years.On the one hand,high-field 7-Tesla magnetic resonance imaging(MRI)has excelled the limited spatial resolution of 3-Tesla MRI,allowing us to enter a new world of mesoscopic imaging from the macroscopic imaging of human brain functions.On the other hand,novel optical pumping magnetometer-magnetoencephalography(OPM-MEG)has broken down the technical barriers of traditional superconducting MEG,which brings imaging of neuronal electromagnetic signals from cortical imaging to whole-brain imaging.This article aims to present a brief introduction regarding the development of conventional MRI and MEG technology,and,more importantly,to delineate that high-field MRI and OPM-MEG complement each other and together will lead us into a new era of functional brain imaging.
文摘This paper briefly summarizes the development of magnetic resonance imaging and spectroscopy in medicine.Aspects of magnetic resonancephysics and-technology relevant at ultra-high magnetic fields as well as current limitations are highlighted.Based on the first promising studies,potential clinical applications at 7 Tesla are suggested.Other aims are to stimulate awareness of the potential of ultra-high field magnetic resonance and to stimulate active participation in much needed basic or clinical research at 7 Tesla or higher.
基金Supported by the National Science and Technology Major Project of China(2012ZX04003081)
文摘An experimental and numerical study on the temperature field induced in the ultra-high frequency induction heating is carried out.With an aim of predicting the thermal history of the workpiece,the influence factors of temperature field,such as the induction frequency,the dimension of coil and the gap between coil and workpiece,are investigated considering temperature-dependent material properties by using FLUX 2Dsoftware.The temperature field characteristic in ultra-high induction heating is obtained and discussed.The numerical values are compared with the experimental results.A good agreement between them is observed with 7.9% errors.
基金Project(2022JJ30583) supported by the Natural Science Foundation of Hunan Province,ChinaProject(21B0315) supported by the Natural Science Research Project of Hunan Education Department,ChinaProject(18ZDXK04) supported by the Civil Engineering Key Discipline Innovation Project of Changsha University of Science and Technology,China。
