Kegang Hua
Johns Hopkins University School of Medicine
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Kegang Hua.
NeuroImage | 2007
Setsu Wakana; Arvind Caprihan; Martina M. Panzenboeck; James H. Fallon; Michele E. Perry; Randy L. Gollub; Kegang Hua; Jiangyang Zhang; Hangyi Jiang; Prachi Dubey; Ari M. Blitz; Peter C.M. van Zijl; Susumu Mori
Tractography based on diffusion tensor imaging (DTI) allows visualization of white matter tracts. In this study, protocols to reconstruct eleven major white matter tracts are described. The protocols were refined by several iterations of intra- and inter-rater measurements and identification of sources of variability. Reproducibility of the established protocols was then tested by raters who did not have previous experience in tractography. The protocols were applied to a DTI database of adult normal subjects to study size, fractional anisotropy (FA), and T2 of individual white matter tracts. Distinctive features in FA and T2 were found for the corticospinal tract and callosal fibers. Hemispheric asymmetry was observed for the size of white matter tracts projecting to the temporal lobe. This protocol provides guidelines for reproducible DTI-based tract-specific quantification.
NeuroImage | 2008
Susumu Mori; Kenichi Oishi; Hangyi Jiang; Li Jiang; Xin Li; Kazi Akhter; Kegang Hua; Andreia V. Faria; Asif Mahmood; Roger P. Woods; Arthur W. Toga; G. Bruce Pike; Pedro Rosa Neto; Alan C. Evans; Jiangyang Zhang; Hao Huang; Michael I. Miller; Peter C. M. van Zijl; John C. Mazziotta
Brain registration to a stereotaxic atlas is an effective way to report anatomic locations of interest and to perform anatomic quantification. However, existing stereotaxic atlases lack comprehensive coordinate information about white matter structures. In this paper, white matter-specific atlases in stereotaxic coordinates are introduced. As a reference template, the widely used ICBM-152 was used. The atlas contains fiber orientation maps and hand-segmented white matter parcellation maps based on diffusion tensor imaging (DTI). Registration accuracy by linear and non-linear transformation was measured, and automated template-based white matter parcellation was tested. The results showed a high correlation between the manual ROI-based and the automated approaches for normal adult populations. The atlases are freely available and believed to be a useful resource as a target template and for automated parcellation methods.
NeuroImage | 2008
Kegang Hua; Jiangyang Zhang; Setsu Wakana; Hangyi Jiang; Xin Li; Daniel S. Reich; Peter A. Calabresi; James J. Pekar; Peter C. M. van Zijl; Susumu Mori
Diffusion tensor imaging (DTI) is an exciting new MRI modality that can reveal detailed anatomy of the white matter. DTI also allows us to approximate the 3D trajectories of major white matter bundles. By combining the identified tract coordinates with various types of MR parameter maps, such as T2 and diffusion properties, we can perform tract-specific analysis of these parameters. Unfortunately, 3D tract reconstruction is marred by noise, partial volume effects, and complicated axonal structures. Furthermore, changes in diffusion anisotropy under pathological conditions could alter the results of 3D tract reconstruction. In this study, we created a white matter parcellation atlas based on probabilistic maps of 11 major white matter tracts derived from the DTI data from 28 normal subjects. Using these probabilistic maps, automated tract-specific quantification of fractional anisotropy and mean diffusivity were performed. Excellent correlation was found between the automated and the individual tractography-based results. This tool allows efficient initial screening of the status of multiple white matter tracts.
NeuroImage | 2006
Laurent Hermoye; Christine Saint-Martin; Guy Cosnard; Seung Koo Lee; Jinna Kim; Marie Cecile Nassogne; Renaud Menten; Philippe Clapuyt; Pamela K. Donohue; Kegang Hua; Setsu Wakana; Hangyi Jiang; Peter C.M. van Zijl; Susumu Mori
Recent advances in diffusion tensor imaging (DTI) have made it possible to reveal white matter anatomy and to detect neurological abnormalities in children. However, the clinical use of this technique is hampered by the lack of a normal standard of reference. The goal of this study was to initiate the establishment of a database of DTI images in children, which can be used as a normal standard of reference for diagnosis of pediatric neurological abnormalities. Seven pediatric volunteers and 23 pediatric patients (age range: 0-54 months) referred for clinical MR examinations, but whose brains were shown to be normal, underwent anatomical and DTI acquisitions on a 1.5 T MR scanner. The white matter maturation, as observed on DTI color maps, was described and illustrated. Changes in diffusion fractional anisotropy (FA), average apparent diffusion constant (ADC(ave)), and T2-weighted (T2W) signal intensity were quantified in 12 locations to characterize the anatomical variability of the maturation process. Almost all prominent white matter tracts could be identified from birth, although their anisotropy was often low. The evolution of FA, shape, and size of the white matter tracts comprised generally three phases: rapid changes during the first 12 months; slow modifications during the second year; and relative stability after 24 months. The time courses of FA, ADC(ave), and T2W signal intensity confirmed our visual observations that maturation of the white matter and the normality of its architecture can be assessed with DTI in young children. The database is available online and is expected to foster the use of this promising technique in the diagnosis of pediatric pathologies.
NeuroImage | 2008
Kenichi Oishi; Karl Zilles; Katrin Amunts; Andreia V. Faria; Hangyi Jiang; Xin Li; Kazi Akhter; Kegang Hua; Roger P. Woods; Arthur W. Toga; G. Bruce Pike; Pedro Rosa-Neto; Alan C. Evans; Jiangyang Zhang; Hao Huang; Michael I. Miller; Peter C. M. van Zijl; John C. Mazziotta; Susumu Mori
Structural delineation and assignment are the fundamental steps in understanding the anatomy of the human brain. The white matter has been structurally defined in the past only at its core regions (deep white matter). However, the most peripheral white matter areas, which are interleaved between the cortex and the deep white matter, have lacked clear anatomical definitions and parcellations. We used axonal fiber alignment information from diffusion tensor imaging (DTI) to delineate the peripheral white matter, and investigated its relationship with the cortex and the deep white matter. Using DTI data from 81 healthy subjects, we identified nine common, blade-like anatomical regions, which were further parcellated into 21 subregions based on the cortical anatomy. Four short association fiber tracts connecting adjacent gyri (U-fibers) were also identified reproducibly among the healthy population. We anticipate that this atlas will be useful resource for atlas-based white matter anatomical studies.
NeuroImage | 2008
Susumu Mori; Jiangyang Zhang; Kegang Hua
Reconstruction of white matter tracts based on diffusion tensor imaging (DTI) is currently widely used in clinical research. This reconstruction allows us to identify coordinates of specific white matter tracts and to investigate their anatomy. Fiber reconstruction, however, relies on manual identification of anatomical landmarks of a tract of interest, which is based on subjective judgment and thus a potential source of experimental variability. Here, an automated tract reconstruction approach is introduced. A set of reference regions of interest (rROIs) known to select a tract of interest was marked in our DTI brain atlas. The atlas was then linearly transformed to each subject, and the rROI set was transferred to the subject for tract reconstruction. Agreement between the automated and manual approaches was measured for 11 tracts in 10 healthy volunteers and found to be excellent (kappa>0.8) and remained high up to 4-5 mm of the linear transformation errors. As a first example, the automated approach was applied to brain tumor patients and strategies to cope with severe anatomical abnormalities are discussed.
Cerebral Cortex | 2009
Kegang Hua; Kenichi Oishi; Jiangyang Zhang; Setsu Wakana; Takashi Yoshioka; Weihong Zhang; Kazi Akhter; Xin Li; Hao Huang; Hangyi Jiang; Peter C.M. van Zijl; Susumu Mori
In the human brain, different regions of the cortex communicate via white matter tracts. Investigation of this connectivity is essential for understanding brain function. It has been shown that trajectories of white matter fiber bundles can be estimated based on orientational information that is obtained from diffusion tensor imaging (DTI). By extrapolating this information, cortical regions associated with a specific white matter tract can be estimated. In this study, we created population-averaged cortical maps of brain connectivity for 4 major association fiber tracts, the corticospinal tract (CST), and commissural fibers. It is shown that these 4 association fibers interconnect all 4 lobes of the hemispheres. Cortical regions that were assigned based on association with the CST and the superior longitudinal fasciculus (SLF) agreed with locations of their known (CST: motor) or putative (SLF: language) functions. The proposed approach can potentially be used for quantitative assessment of the effect of white matter abnormalities on associated cortical regions.
Neuropharmacology | 2012
S. Hossein Fatemi; Timothy D. Folsom; Robert J. Rooney; Susumu Mori; Tess E. Kornfield; Teri J. Reutiman; Rachel E. Kneeland; Stephanie B. Liesch; Kegang Hua; John Hsu; Divyen H. Patel
Researchers have long noted an excess of patients with schizophrenia were born during the months of January and March. This winter birth effect has been hypothesized to result either from various causes such as vitamin D deficiency (McGrath, 1999; McGrath et al., 2010), or from maternal infection during pregnancy. Infection with a number of viruses during pregnancy including influenza, and rubella are known to increase the risk of schizophrenia in the offspring (Brown, 2006). Animal models using influenza virus or Poly I:C, a viral mimic, have been able to replicate many of the brain morphological, genetic, and behavioral deficits of schizophrenia (Meyer et al., 2006, 2008a, 2009; Bitanihirwe et al., 2010; Meyer and Feldon, 2010; Short et al., 2010). Using a murine model of prenatal viral infection, our laboratory has shown that viral infection on embryonic days 9, 16, and 18 leads to abnormal expression of brain genes and brain structural abnormalities in the exposed offspring (Fatemi et al., 2005, 2008a,b, 2009a,b). The purpose of the current study was to examine gene expression and morphological changes in the placenta, hippocampus, and prefrontal cortex as a result of viral infection on embryonic day 7 of pregnancy. Pregnant mice were either infected with influenza virus [A/WSN/33 strain (H1N1)] or sham-infected with vehicle solution. At E16, placentas were harvested and prepared for either microarray analysis or for light microscopy. We observed significant, upregulation of 77 genes and significant downregulation of 93 genes in placentas. In brains of exposed offspring following E7 infection, there were changes in gene expression in prefrontal cortex (6 upregulated and 24 downregulated at P0; 5 upregulated and 14 downregulated at P56) and hippocampus (4 upregulated and 6 downregulated at P0; 6 upregulated and 13 downregulated at P56). QRT-PCR verified the direction and magnitude of change for a number of genes associated with hypoxia, inflammation, schizophrenia, and autism. Placentas from infected mice showed a number of morphological abnormalities including presence of thrombi and increased presence of immune cells. Additionally, we searched for presence of H1N1 viral-specific genes for M1/M2, NA, and NS1 in placentas of infected mice and brains of exposed offspring and found none. Our results demonstrate that prenatal viral infection disrupts structure and gene expression of the placenta, hippocampus, and prefrontal cortex potentially explaining deleterious effects in the exposed offspring without evidence for presence of viral RNAs in the target tissues.
Schizophrenia Bulletin | 2014
Bagrat Abazyan; Jenifer Dziedzic; Kegang Hua; Sofya Abazyan; Chunxia Yang; Susumu Mori; Mikhail V. Pletnikov; Tomás R. Guilarte
The glutamatergic hypothesis of schizophrenia suggests that hypoactivity of the N-methyl-D-aspartate receptor (NMDAR) is an important factor in the pathophysiology of schizophrenia and related mental disorders. The environmental neurotoxicant, lead (Pb(2+)), is a potent and selective antagonist of the NMDAR. Recent human studies have suggested an association between prenatal Pb(2+) exposure and the increased likelihood of schizophrenia later in life, possibly via interacting with genetic risk factors. In order to test this hypothesis, we examined the neurobehavioral consequences of interaction between Pb(2+) exposure and mutant disrupted in schizophrenia 1 (mDISC1), a risk factor for major psychiatric disorders. Mutant DISC1 and control mice born by the same dams were raised and maintained on a regular diet or a diet containing moderate levels of Pb(2+). Chronic, lifelong exposure of mDISC1 mice to Pb(2+) was not associated with gross developmental abnormalities but produced sex-dependent hyperactivity, exaggerated responses to the NMDAR antagonist, MK-801, mildly impaired prepulse inhibition of the acoustic startle, and enlarged lateral ventricles. Together, these findings support the hypothesis that environmental toxins could contribute to the pathogenesis of mental disease in susceptible individuals.
International Journal of Developmental Neuroscience | 2012
Hongen Wei; Susumu Mori; Kegang Hua; Xiaohong Li
Abnormal neuroimmune responses have been reported to be associated with autism and could be appropriate targets for pharmacologic intervention. Our previous studies showed that neuroimmune factor, interleukin (IL)‐6, was significantly elevated in the fontal cortex and cerebellum of autistic subjects. The IL‐6 overexpressing mice displayed several autism‐like features as well as an abnormal dendritic spine morphology and synaptic function. The purpose of this study was to examine the volumetric differences in the brain of IL‐6 overexpressing mice and compare with corresponding control mice using magnetic resonance imaging. Here we show that IL‐6 overexpressing mice display an increase in the total brain volume. In addition, the lateral ventricle is also enlarged in the IL‐6 overexpressing mice. The brain structures surrounding the lateral ventricle were squeezed and deformed from the normal location. These results indicate that IL‐6 elevation in the brain could mediate neuroanatomical abnormalities. Taking together with our previous findings, a mechanism by which IL‐6 may be involved in the pathogenesis of autism is proposed.