Thesis (Ph. D. in Physics)--Vanderbilt University, Dec. 2007. / Title from title screen. Includes bibliographical references.

Background: To explore normal-appearing white matter (NAWM) in pediatric-onset multiple sclerosis (MS) patients, using diffusion tensor imaging (DTI). DTI study provides measures of WM integrity in adult MS patients. Pediatric MS patients provide a uniquely early window for exploring pathological components of myelin disruption. Methods: DTI data were obtained for 23 pediatric MS patients and 17 healthy children. Images were acquired using GE LX1.5T scanner (DTI parameters: 25 directions, 5mm slice thickness, b=1000s/mm2). Fractional anisotropy (FA) and apparent diffusion co-efficient (ADC) were analyzed in lesions and NAWM throughout corpus callosum (CC) and hemispheres. Results: Altered NAWM integrity in MS patients relative to controls is demonstrated by: reduced FA values (p<0.0001) and elevated ADC values (p<0.05) throughout CC and hemispheres. Conclusions: DTI measures show widespread disruption of WM integrity in children with MS extending beyond visible lesions. These findings implicate diffuse and potentially very early WM degeneration in MS pathobiology.

Background: To explore normal-appearing white matter (NAWM) in pediatric-onset multiple sclerosis (MS) patients, using diffusion tensor imaging (DTI). DTI study provides measures of WM integrity in adult MS patients. Pediatric MS patients provide a uniquely early window for exploring pathological components of myelin disruption. Methods: DTI data were obtained for 23 pediatric MS patients and 17 healthy children. Images were acquired using GE LX1.5T scanner (DTI parameters: 25 directions, 5mm slice thickness, b=1000s/mm2). Fractional anisotropy (FA) and apparent diffusion co-efficient (ADC) were analyzed in lesions and NAWM throughout corpus callosum (CC) and hemispheres. Results: Altered NAWM integrity in MS patients relative to controls is demonstrated by: reduced FA values (p<0.0001) and elevated ADC values (p<0.05) throughout CC and hemispheres. Conclusions: DTI measures show widespread disruption of WM integrity in children with MS extending beyond visible lesions. These findings implicate diffuse and potentially very early WM degeneration in MS pathobiology.

Diffusion Tensor Magnetic Resonance Imaging (DTI) is a recently-developed technique that can image in vivo the white matter pathways of the central nervous system. This study used 12-direction diffusion-weighted MRI data from nine stroke patients acquired as part of a three-year stroke rehabilitation study coordinated by the Movement Neuroscience Laboratory at the University of Auckland. DTI was used to investigate corticospinal connectivity. From the FA maps, it is found that in those patients whose motor connectivity has been compromised by the stroke to the extent that no motor evoked potential (MEP) can be elicited from a selected affected muscle group, the asymmetry in mean FA values in the posterior limbs of the internal capsules (PLICs) is correlated with functional recovery as measured by the Fugl-Meyer clinical score. Using probabilistic tractography in the contralesional hemisphere produced CST location and somatotopy results that were consistent with those of previous studies. However, in the ipsilesional hemisphere, connectivity results were highly variable. A measure of change in symmetry of mean connectivity is found to correlate with functional recovery as measured by change in FM score. This supports previous work which has correlated CST integrity and functional improvement and it supports the theory that functional recovery after stroke depends on the extent to which motor CNS symmetry can be regained in the new post-stroke architecture. It also suggests that the movement of the fMRI activations occurs in such a way as to make the most of the preserved white matter connectivity.

Thesis (Ph. D. in Biomedical Engineering)--Vanderbilt University, May 2009. / Title from title screen. Includes bibliographical references.

Thesis (Ph.D.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaves 169-176).

Thesis (M.S.)--University of Alabama at Birmingham, 2008. / Additional advisors: Louis B. Nabors, James M. Markert, Donald B. Twieg. Description based on contents viewed July 8, 2009; title from PDF t.p. Includes bibliographical references (p. 73-79).

Thesis (M.S.)--Michigan State University. Dept. of Physics, 2008. / Title from PDF t.p. (viewed on Aug. 7, 2009) Includes bibliographical references (p. 55-57). Also issued in print.

Thesis (Ph. D.)--University of California, San Diego, 2008. / Title from first page of PDF file (viewed November 10, 2008). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

Thesis (M.S.)--West Virginia University, 2010. / Title from document title page. Document formatted into pages; contains viii, 75 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 72-75).