Diffusion Tensor Imaging of the Central Nervous System Following an Injury to the Spinal Cord and Cell Transplant

DIFFUSION TENSOR IMAGING OF THE CENTRAL NERVOUS SYSTEM FOLLOWING AN INJURY TO THE SPINAL CORD AND CELL TRANSPLANT Michael B. Jirjis, B.S. Marquette University, 2013 The purpose of this dissertation research was to characterize the use of magnetic resonance diffusion tensor imaging (DTI) as a diagnostic and prognostic tool in understanding the changes that occur throughout the spinal cord and brain following a spinal cord injury (SCI) and following stem cell transplant. The diffusion of water inside the nervous system is dramatically altered around the lesion site following a traumatic SCI. However, following damage to the spinal cord, little is known about the diffusion characteristics away from an injury and even less is understood about DTI’s sensitivity to structural changes that occur following regenerative transplant therapies. The noninvasive nature of DTI could potentially allow for diagnostic and prognostic indicators of an SCI remote from injury and could provide physicians a method for tracking and monitoring the effectiveness of injected stem cells. To evaluate the sensitivity of DTI to structural changes in the central nervous system (CNS) following a traumatic SCI, diffusion metrics in the brain and cervical spinal cord were compared for four different injury severities in a thoracic contusion model of a rat SCI. Structural changes in the cervical region of the spinal cord after transplantation of C17.2 neuronal stem cells were also examined with the use of DTI. The findings from this dissertation suggest that diffusion tensor imaging is sensitive to changes in tissue structure in regions remote from injury and for cellular environments that increased astrocytic sprouting as a result of stem cell transplant. Mean water diffusion in the distal locations of the spinal cord and in the brain decreased following SCI. Neuronal stem cells that are known to elicit astrocytic proliferation produced mean increases in water diffusion. These results further clarify the potential for DTI to provide physicians a method to non-invasively monitor how the CNS changes following SCI and detect structural changes elicited by transplanted regenerative treatments.