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MULTIMODAL NEUROIMAGING IN BLAST INDUCED TRAUMATIC BRAIN INJURY
Title
MULTIMODAL NEUROIMAGING IN BLAST INDUCED TRAUMATIC BRAIN INJURY
Creator
Stout, Jeffrey
Date
2015, 2015-12
Description
Recent military conflicts in Iraq and Afghanistan have resulted in an increase in the number of blast related traumatic brain injury (TBI)...
Show moreRecent military conflicts in Iraq and Afghanistan have resulted in an increase in the number of blast related traumatic brain injury (TBI) cases, currently estimated in excess of 300,000. Current neuroimaging methods, including MRI and CT, are generally not sensitive enough to diagnose blast TBL This research represents several advancements in the understanding of long-term TBI related changes as well as imaging comorbid neurocognitive deficits and psychopathologies. The multi modal approach was taken to leverage the differing sensitivities of each imagmg modality to better identify neuroimaging changes associated with blast TBL T l-weighted MRI was utilized to assess cortical thickness reduction in the TBI subjects, resulting in right temporal lobe decreases that were associated with posttraumatic stress disorder (PTSD) and neurobehavioral symptom indices. Utilizing positron emission tomography (PET), several areas of metabolic change were associated with blast TBI, PTSD, repetitive head injury, and TBI severity. Functional MRI was used to assess working memory deficit, demonstrating relatively normal function in the mild TBI subject, except for at higher cognitive loads; whereas the moderate TBI subjects demonstrated a trend of dysfunction at most levels of cognitive load. Fractional anisotropy (FA) changes were assessed using diffusion tensor imaging, however there was no resulting statistical significance due to differences in the locations of single subject FA changes that could not be realized at the group level using standard analyses. Investigation into multimodal searchlight to integrate the sensitivities of each imaging modality into a single statistical measure, provided enhanced sensitivity to TBI-induced changes in neuroimaging versus single modal searchlight and identified several clusters of change most notably in the cerebellum, temporal lobes, brainstem, and internal capsule. Through a multimodal approach we have shown several areas of damage and dysfunction associated with blast TBI in subjects greater than one year post injury. This research is important due to the large numbers of subjects currently experiencing long-term post concussive symptoms. Our findings show that both TBI and PTSD playa large role in the changes identified on neuroimaging. This research can provide information to assist in the understanding , diagnosis , and treatment of blast TBI.
Ph.D. in Biomedical Engineering, December 2015
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Development of Human Brain Atlas Resources
Title
Development of Human Brain Atlas Resources
Creator
Qi, Xiaoxiao
Date
2020
Description
Digital human brain atlases play an increasingly critical role and are widely used in neuroimaging studies such as developing biomarkers,...
Show moreDigital human brain atlases play an increasingly critical role and are widely used in neuroimaging studies such as developing biomarkers, training data for machine learning algorithms, functional connectivity analysis and so on. A brain atlas typically consists of brain templates of different imaging modalities that are representative of individual brains under study in a standard atlas space and semantic labels that delineate brain regions according to the characteristics of the underlying tissue.The IIT Human Brain Atlas project has developed the state-of-the-art diffusion tensor imaging (DTI) template, high angular resolution diffusion imaging (HARDI) template, and anatomical templates for the young adult brain in a standardized space. The probabilistic maps of gray matter (GM) labels and tissue segmentations were also constructed based on the anatomical information of the atlas. This thesis introduced an enhanced T1-weighted template that were developed by combining information from both diffusion and anatomical data. The GM labels and tissue segmentation maps in the standardized space were also improved. Existing white matter (WM) atlases typically lack specificity in terms of brain connectivity. A new approach named regionconnect was developed in this work based on precalculated average healthy adult brain connectivity information stored in standard space in a fashion that allows fast retrieval and integration. This thesis first generated and evaluated the white matter connectome of the IIT Human Brain Atlas v.5.0. Next, the new white matter connectome was used to develop multi-layer, connectivity-based labels for each white matter voxel of the atlas, consistent with the fact that each voxel may contain axons from multiple connections. The regionconnect algorithm was then developed to rapidly integrate information contained in the multi-layer labels across voxels of a white matter region and to generate a list of the most probable connections traversing that region. The regionconnect algorithm as well as the white matter tractogram and connectome, multi-layer, connectivity-based labels, and associated resources developed for the IIT Human Brain Atlas v.5.0 in this work are available at www.nitrc.org/projects/iit. Furthermore, it was well established that use of a young adult atlas in studies of older adults is inappropriate due to the age-related characteristic changes of the brain, resulting in an increasing demand of digital brain atlases for the older adults. To fulfill this demand, a function of fiber orientation distribution (fODF) template that is representative of older adults was developed in a standardized atlas space for studies of white matter of older adult human brains, which built a solid foundation for the development of the white matter resources for the older adults human brain atlas.
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