A complete scientific understanding of human nature requires delineation of the neurobiological characteristics underlying the unique features of the human mind. This effort can be facilitated by comparing the human brain with the brains of other living primate species. Humans are more susceptible to neurodegenerative diseases than other primate species, including our closest living primate relatives, the chimpanzees. Comparing age-related changes in brain structure between humans and non-human primates could, therefore, potentially shed light on the neurological basis of this human vulnerability. Further, human brains are lateralized with specialized cognitive and behavioral functions. Comparing the magnitude of hemispheric asymmetries in brain structure between humans and non-human primates can probe insights into this human specific capability and learn more about human evolution. Diffusion weighted MRI protocols were developed for different species, taking into account their neuroanatomical differences. For Chimpanzees, a multi-shot DWI sequence was developed and compared with a single-shot DWI sequence to determine which provided a better quality diffusion data free of acquisition related artifacts. Different simulation techniques were used to evaluate the effect of segmentation-related motion artifact (ghosting) on the multi-shot DTI data. Although both protocols generated high-resolution diffusion MRI data with correctable susceptibility-induced distortions, the single-shot protocol enables the acquisition of the high-resolution diffusion MRI data freed of ghosting and with twice the signal-to-noise ratio (SNR), for the same scan duration. The acquired chimpanzee and macaque diffusion data were used to compare the magnitude of microstructural asymmetries and age-related decline of brain white matter with those in humans. Hemispheric asymmetry results show a pattern of strong leftward asymmetry in human DTI indices that differs markedly from the chimpanzee (multi-shot data) and the rhesus macaque patterns involving both rightward and leftward asymmetries. The magnitude of leftward asymmetry increased for chimpanzees scanned with single-shot DTI sequence. Region of interest analyses within the corpus callosum revealed a significant age-related increase in fractional anisotropy (FA) in the genu for chimpanzees (multi-shot data) and no significant change in any region for macaques. Additionally, voxel-wise analysis using Tract Based Spatial Statistics (TBSS) revealed widespread age-related FA increases for chimpanzees (multi-shot data) and weak age-related decreases in FA for macaques across most white matter tracts. Overall, results from these multi-shot data analyses suggest that rhesus monkeys show age-related decreases in white matter integrity that parallel changes found in humans, whereas chimpanzees show age-related increases in white matter integrity. On the contrary, the single-shot data results for chimpanzees revealed no significant relationship between age and the different DTI indices. These noteworthy species differences may help to explain the unique features of the human mind and why humans are more susceptible to neurodegenerative diseases. Furthermore, these studies demonstrate the need for complementary histological studies of white matter microstructure in humans, chimpanzees and macaques to clarify the cellular and molecular basis of these findings.

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Hu, Xiaoping; Committee Member: Brummer, Marijn; Committee Member: Duong, Tim; Committee Member: Keilholz, Shella; Committee Member: Schumacher, Eric. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--University of California, San Diego and San Diego State University, 2008. / Title from first page of PDF file (viewed September 4, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 81-94).

Thesis (M. Sc.)--Carleton University, 2003. / Includes bibliographical references (p. 90-98). Also available in electronic format on the Internet.

Thesis (Ph. D.)--Cornell University, May, 2007. / Vita. Includes bibliographical references (leaves 162-189).

Thesis (M.Sc.). / Written for the Medical Physics Unit. Title from title page of PDF (viewed 2009/09/07). Includes bibliographical references.

Orientador: Roberto de Alencar Lotufo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-15T05:13:40Z (GMT). No. of bitstreams: 1 Rittner_Leticia_D.pdf: 6505295 bytes, checksum: 27a551a00d899d4e4e5273b6de791332 (MD5) Previous issue date: 2009 / Resumo: O objetivo principal desta tese é propor um método de segmentação para imagens de tensores de difusão baseado na transformada de watershed. Ao invés de adaptar o watershed para trabalhar com imagens tensoriais, definimos mapas escalares baseados na morfologia matemática que retêm a informação relevante contida nos tensores para, a partir deles, conseguir a segmentação da imagem aplicando a transformada de watershed. Novos mapas baseados em operadores da morfologia matemática são então propostos e analisados. O principal mapa escalar proposto é o gradiente morfológico tensorial (TMG). Um estudo comparativo do TMG com os diversos mapas escalares já existentes demonstra sua superioridade na tarefa de segmentação. Os resultados da segmentação baseada no TMG e no watershed hierárquico são comparáveis com resultados de segmentação baseada em atlas. O método proposto é usado para segmentar os núcleos do tálamo, uma tarefa de grande importância para a neuro-ciência. O método também é adaptado para segmentação de imagens coloridas, sendo necessária para tanto a criação de uma representação tensorial específica / Abstract: The main goal of this thesis is to present a segmentation method for diffusion tensor images, based on the watershed transform. Instead of adapting the watershed to work with tensorial images, scalar maps based on mathematical morphology, retaining relevant information from tensors, were defined. The desired segmentation is achieved by applying the watershed over these scalar maps. New scalar maps, based on mathematical morphology, are defined and analyzed. The tensorial morphological gradient (TMG) is the most important among the proposed scalar maps. A comparative study of the TMG with the existing scalar maps shows its superiority in the segmentation task. Segmentation results obtained by the hierarchical watershed over the TMG are comparable to atlas-based segmentation. The proposed method is used to segment the thalamic nuclei, an important task for neuroscience. The method is also adapted to segment color images, requiring a definition of a specific tensorial representation / Doutorado / Engenharia de Computação / Doutor em Engenharia Elétrica

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第13125号 / 論医博第2134号 / 新制||医||1024(附属図書館) / (主査)教授 宮本 享, 教授 村井 俊哉, 教授 井上 治久 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Fong, Kwan Ying. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 90-103). / Abstracts in English and Chinese. / Chapter Chapter 1: --- "Introduction, problems and objectives" --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Problems --- p.3 / Chapter 1.3 --- Objectives --- p.3 / Chapter Chapter 2: --- Background --- p.4 / Chapter 2.1. --- Head and Neck Cancer --- p.4 / Chapter 2.2 --- Diagnostic Imaging of Head and Neck Cancer --- p.5 / Chapter 2.3. --- Magnetic Resonance Imaging- Physics --- p.8 / Chapter 2.3.1 --- Nuclear Magnetic Resonance Principle --- p.8 / Chapter 2.3.2 --- Proton Magnetic Resonance Imaging --- p.8 / Chapter 2.3.3 --- Relaxation --- p.12 / Chapter 2.3.4 --- Tl- and T2-weighted Imaging --- p.12 / Chapter 2.3.5 --- Diffusion Weighted Imaging (DWI) --- p.13 / Chapter 2.3.6 --- Magnetic Resonance Spectroscopy- Single Voxel Spectroscopy and Chemical Shift Imaging --- p.15 / Chapter Chapter 3: --- Diffusion-weighted imaging in the evaluation head of and neck cancer --- p.21 / Chapter 3.1 --- Introduction - Diffusion-Weighted Imaging in Tumors --- p.21 / Chapter 3.2 --- DWI of Nasopharyngeal Carcinoma --- p.22 / Chapter 3.2.1 --- Introduction and Objectives --- p.22 / Chapter 3.2.2. --- Methods --- p.23 / Chapter 3.2.3. --- Results --- p.27 / Chapter 3.2.4 --- Discussion --- p.31 / Chapter 3.3 --- DWI of Primary Tumors: Comparison of NPC with Squamous Cell Carcinoma and Extra-nodal Non-Hodgkin Lymphoma --- p.33 / Chapter 3.3.1 --- Introduction and Objectives --- p.33 / Chapter 3.3.2. --- Methods --- p.34 / Chapter 3.3.3. --- Results --- p.35 / Chapter 3.3.4 --- Discussion --- p.42 / Chapter 3.3.5 --- Summary of DWI in Head and Neck Cancer --- p.44 / Chapter Chapter 4: --- Chemical shift imaging of head and neck tumors --- p.45 / Chapter 4.1 --- Introduction - Single Voxel Spectroscopy and Chemical Shift Imaging --- p.45 / Chapter 4.2 --- CSI - Methods Used to Reduce Magnetic Field Inhomogeneity --- p.48 / Chapter 4.3 --- Phantom studies - CSI Experiments Using Phantoms --- p.51 / Chapter 4.3.1 --- Introduction and Objectives --- p.51 / Chapter 4.3.2. --- Methods --- p.51 / Chapter 4.3.3 --- Experiment and MR Protocol --- p.54 / Chapter 4.3.4 --- Data Analysis --- p.58 / Chapter 4.3.5 --- Phantom Experimental Results --- p.59 / Chapter 4.3.6 --- Discussion and Conclusion on Phantom Experiments --- p.69 / Chapter 4.4 --- In vivo CSI Study of Human Head and Neck Tumors --- p.72 / Chapter 4.4.1 --- Introduction and Objectives --- p.72 / Chapter 4.4.2 --- Patient Selection --- p.73 / Chapter 4.4.3 --- MRI and CSI Protocol --- p.73 / Chapter 4.4.4 --- Data Analysis --- p.74 / Chapter 4.4.5 --- Results from CSI on Patients --- p.74 / Chapter 4.4.6 --- Discussion and Conclusion of CSI on Patients --- p.81 / Chapter Chapter 5: --- "Summary, conclusion and future studies" --- p.87 / Chapter 5.1 --- Summary --- p.87 / Chapter 5.2 --- Conclusion --- p.89 / Chapter 5.3 --- Future Studies --- p.89 / References --- p.90 / Publications --- p.104

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed Feb 13, 2009). Includes bibliographical references.