Objective High resolution structural MR imaging can reveal structural characteristics of cerebral cortex and provide an insight into normal brain development and neuropsychological diseases. The aim of this study was ...Objective High resolution structural MR imaging can reveal structural characteristics of cerebral cortex and provide an insight into normal brain development and neuropsychological diseases. The aim of this study was to compare cortical structural characteristics of normal human brain between 3T and 7T MRI systems using surface-based morphometry based on high resolution structural MR imaging.Methods Twelve healthy volunteers were scanned by both 3T with 3D T1-weighted fast spoiled gradient recalled echo (3D T1-FSPGR) sequence and 7T with 3D T1-weighted magnetization-prepared rapid gradient echo (3D T1-MPRAGE) sequence. MRI data were processed with FreeSurfer. The cortical thickness,white and gray matter surface area, convexity, and curvature from data of 3T and 7T were measured and compared by paired t-test.Results Measurements of mean cortical thickness, total white matter surface area and gray matter surface area of 3T were larger than those of 7T (left hemisphere: P=0.000, 0.006, 0.020 respectively; right hemisphere: P=0.000, 0.000, 0.000 respectively). Surface-based morphometry over the whole brain demonstrated both reduced and increased measurements of cortical thickness, white and gray surface area,convexity, and curvature at 7T compared to 3T.Conclusions Inconsistency of brain structural attribute between 3T and 7T was confirmed, and researchers should be cautious about data when using ultrahigh field MR system to investigate brain structural changes.展开更多
This paper describes a technique to estimate surface-based duct parameters by using a simple ray tracing/correlation method. The approach is novel in that it incorporates the Spearman rank-order correlation scheme bet...This paper describes a technique to estimate surface-based duct parameters by using a simple ray tracing/correlation method. The approach is novel in that it incorporates the Spearman rank-order correlation scheme between the observed surface clutter and the surface ray density for a given propagation path. The simulation results and the real data results both demonstrate the ability of this method to estimate surface-based duct parameters. Compared with the results obtained by a modified genetic algorithm combined with the parabolic wave equation, the results retrieved from the ray tracing/correlation scheme show a minor reduction in accuracy but a great improvement on computation time. Therefore the ray tracing/correlation method might be used as a precursor to more sophisticated and slower techniques, such as genetic algorithm and particle filters, by narrowing the parameter search space and providing a comprehensive and more efficient estimation algorithm.展开更多
Objective To investigate cerebral structural signatures of the bulbar-and spinal-onset amyotrophic lateral sclerosis(ALS) using voxel-based morphometry on magnetic resonance imaging.Methods The MR structural images of...Objective To investigate cerebral structural signatures of the bulbar-and spinal-onset amyotrophic lateral sclerosis(ALS) using voxel-based morphometry on magnetic resonance imaging.Methods The MR structural images of the brain were obtained from 65 ALS patients(15 bulbar-onset, 50 spinalonset) and 65 normal controls(NC) on a 3.0 T MRI system. Gray matter(GM) volume changes were investigated by voxel-based morphometry, and the distribution of the brain regions with volume changes was compared between ALS and normal controls, as well as between bulbar-onset and spinal-onset ALS based on Neuromorphometrics atlas.Results On voxel-level the decreased volume of brain regions in ALS patients was located in the right precentral gyrus(r Prc Gy) and right middle frontal gyrus compared with that in NC. The bulbar-onset ALS presented extramotor cortex atrophy(fronto-temporal pattern), including left medial orbital gyrus, left inferior temporal gyrus and right middle temporal gyrus; the spinal-onset ALS suffered from motor cortex atrophy(r Prc Gy dominance) and extra-motor cortex atrophy(fronto-temporal and extra-fronto-temporal pattern) compared with NC. The spinal-onset ALS featured by GM volume loss of left postcentral gyrus and bulbar-onset ALS featured by GM volume loss of left middle temporal gyrus compared with each other. Conclusions The asymmetric GM atrophy of the motor cortex and extra-motor cortex represents the common MRI structural signatures of spinal-onset ALS, and sole extra-motor cortex atrophy represents the structural signatures of bulbar-onset ALS. The present study also demonstrated that the pattern of GM damage is likely to distribute wider in spinal-onset ALS than in bulbar-onset ALS.展开更多
Twenty samples of endothelia removed from normal and post penetrating keratoplas-ty (0.5,1,2,3 months after penetrating keratoplasty) were observed by scanning electron mi-croscopy.The photographs of the endothelia in...Twenty samples of endothelia removed from normal and post penetrating keratoplas-ty (0.5,1,2,3 months after penetrating keratoplasty) were observed by scanning electron mi-croscopy.The photographs of the endothelia in graft-host junction were analyzed by computer-assisted image analysis system,and the morphometric indexes examined were area of the cells,perimeters,density,figure coefficient,long axis,coefficient of variation of the area,and oth-ers.Results showed that the morphology and the density of the endothelial cells changed obvi-ously after operation and improved slowly but progressively with time although at 3 monthspostoperatively some differences still existed.By using the new techniques,the experiment con-firmed and enriched the theories on the corneal endothelial wound-healing,revealing some ofthe new characters of the endothelial wound-healing following penetrating keratoplasty.展开更多
Many studies have shown the functional relevance of cross-modal plasticity in blind men. In order to study the changes of their brain structure, voxel-based morphometry （VBM） methods are used. The regional gray matt...Many studies have shown the functional relevance of cross-modal plasticity in blind men. In order to study the changes of their brain structure, voxel-based morphometry （VBM） methods are used. The regional gray matter （GM） and white matter （WM） concentrations of magnetic resonance （MR） images from 11 blind people and 9 sighted control subjects are compared using standard VBM. Optimized VBM is also discussed to measure the absolute local volume of GM or WM. Consistent results are achieved by statistical analysis with these methods. There are distinct differences not only in visual cortex but also the sensory area, auditory area and motor area. GM concentrations in blind men significantly decreased in Brodmann 7 and 22. While in Brodmann 18 and 19, GM concentration increased. GM volumes decreased in Brodmann 3, 4, 6, 9 and 45. On the other hand, both WM concentration and volume increased in Brodmann 7. These results suggest that early visual deprivation can lead to changes in the brain structural anatomy which is consistent with the cortical cross-modal reorganization found by functional imaging. It may help to discover the relationship between the brain structural anatomy and the brain functional data of blind men at a macroscopic level from neuroimaging perspective.展开更多
基金Fund supported by National Natural Science Foundation of China (81171319), the Foundation for Medical and Health Sci & Tech Innovation Project of Sanya (2016YW37) and the Special Financial Grant from China Postdoctoral Science Foundation (2014T70960).
文摘Objective High resolution structural MR imaging can reveal structural characteristics of cerebral cortex and provide an insight into normal brain development and neuropsychological diseases. The aim of this study was to compare cortical structural characteristics of normal human brain between 3T and 7T MRI systems using surface-based morphometry based on high resolution structural MR imaging.Methods Twelve healthy volunteers were scanned by both 3T with 3D T1-weighted fast spoiled gradient recalled echo (3D T1-FSPGR) sequence and 7T with 3D T1-weighted magnetization-prepared rapid gradient echo (3D T1-MPRAGE) sequence. MRI data were processed with FreeSurfer. The cortical thickness,white and gray matter surface area, convexity, and curvature from data of 3T and 7T were measured and compared by paired t-test.Results Measurements of mean cortical thickness, total white matter surface area and gray matter surface area of 3T were larger than those of 7T (left hemisphere: P=0.000, 0.006, 0.020 respectively; right hemisphere: P=0.000, 0.000, 0.000 respectively). Surface-based morphometry over the whole brain demonstrated both reduced and increased measurements of cortical thickness, white and gray surface area,convexity, and curvature at 7T compared to 3T.Conclusions Inconsistency of brain structural attribute between 3T and 7T was confirmed, and researchers should be cautious about data when using ultrahigh field MR system to investigate brain structural changes.
基金Project supported by the National Natural Science Foundation of China (Grant No. 40775025)
文摘This paper describes a technique to estimate surface-based duct parameters by using a simple ray tracing/correlation method. The approach is novel in that it incorporates the Spearman rank-order correlation scheme between the observed surface clutter and the surface ray density for a given propagation path. The simulation results and the real data results both demonstrate the ability of this method to estimate surface-based duct parameters. Compared with the results obtained by a modified genetic algorithm combined with the parabolic wave equation, the results retrieved from the ray tracing/correlation scheme show a minor reduction in accuracy but a great improvement on computation time. Therefore the ray tracing/correlation method might be used as a precursor to more sophisticated and slower techniques, such as genetic algorithm and particle filters, by narrowing the parameter search space and providing a comprehensive and more efficient estimation algorithm.
基金Supported by the grant of the National Natural Sciences Foundation of China(30470512)
文摘Objective To investigate cerebral structural signatures of the bulbar-and spinal-onset amyotrophic lateral sclerosis(ALS) using voxel-based morphometry on magnetic resonance imaging.Methods The MR structural images of the brain were obtained from 65 ALS patients(15 bulbar-onset, 50 spinalonset) and 65 normal controls(NC) on a 3.0 T MRI system. Gray matter(GM) volume changes were investigated by voxel-based morphometry, and the distribution of the brain regions with volume changes was compared between ALS and normal controls, as well as between bulbar-onset and spinal-onset ALS based on Neuromorphometrics atlas.Results On voxel-level the decreased volume of brain regions in ALS patients was located in the right precentral gyrus(r Prc Gy) and right middle frontal gyrus compared with that in NC. The bulbar-onset ALS presented extramotor cortex atrophy(fronto-temporal pattern), including left medial orbital gyrus, left inferior temporal gyrus and right middle temporal gyrus; the spinal-onset ALS suffered from motor cortex atrophy(r Prc Gy dominance) and extra-motor cortex atrophy(fronto-temporal and extra-fronto-temporal pattern) compared with NC. The spinal-onset ALS featured by GM volume loss of left postcentral gyrus and bulbar-onset ALS featured by GM volume loss of left middle temporal gyrus compared with each other. Conclusions The asymmetric GM atrophy of the motor cortex and extra-motor cortex represents the common MRI structural signatures of spinal-onset ALS, and sole extra-motor cortex atrophy represents the structural signatures of bulbar-onset ALS. The present study also demonstrated that the pattern of GM damage is likely to distribute wider in spinal-onset ALS than in bulbar-onset ALS.
文摘Twenty samples of endothelia removed from normal and post penetrating keratoplas-ty (0.5,1,2,3 months after penetrating keratoplasty) were observed by scanning electron mi-croscopy.The photographs of the endothelia in graft-host junction were analyzed by computer-assisted image analysis system,and the morphometric indexes examined were area of the cells,perimeters,density,figure coefficient,long axis,coefficient of variation of the area,and oth-ers.Results showed that the morphology and the density of the endothelial cells changed obvi-ously after operation and improved slowly but progressively with time although at 3 monthspostoperatively some differences still existed.By using the new techniques,the experiment con-firmed and enriched the theories on the corneal endothelial wound-healing,revealing some ofthe new characters of the endothelial wound-healing following penetrating keratoplasty.
基金the National Natural Science Foundation of China (30400136)
文摘Many studies have shown the functional relevance of cross-modal plasticity in blind men. In order to study the changes of their brain structure, voxel-based morphometry （VBM） methods are used. The regional gray matter （GM） and white matter （WM） concentrations of magnetic resonance （MR） images from 11 blind people and 9 sighted control subjects are compared using standard VBM. Optimized VBM is also discussed to measure the absolute local volume of GM or WM. Consistent results are achieved by statistical analysis with these methods. There are distinct differences not only in visual cortex but also the sensory area, auditory area and motor area. GM concentrations in blind men significantly decreased in Brodmann 7 and 22. While in Brodmann 18 and 19, GM concentration increased. GM volumes decreased in Brodmann 3, 4, 6, 9 and 45. On the other hand, both WM concentration and volume increased in Brodmann 7. These results suggest that early visual deprivation can lead to changes in the brain structural anatomy which is consistent with the cortical cross-modal reorganization found by functional imaging. It may help to discover the relationship between the brain structural anatomy and the brain functional data of blind men at a macroscopic level from neuroimaging perspective.
