Dissertation (Ph.D.) -- Worcester Polytechnic Institute and University of Massachusetts Medical School. / Keywords: multispectral analysis ; RIF-1; spreading depression; diffusion; MEMRI; stroke. Includes bibliographical references (p. 229-232).

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: Amplifer design. Includes bibliographical references (p. 89-91).

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: Magnetic Resonance Imaging; Radio Frequency Coil; Breast Cancer; Imaging Systems. Includes bibliographical references (leaves 118-123).

Magnetic Resonance Imaging (MRI) is a non-invasive procedure used in the medical community as a powerful way of creating images of the human anatomy. MRI is preferred over other examination techniques such as X-ray computed tomography (CT) because of its excellent soft tissue discrimination as well as the absence of ionizing radiation. Currently most clinical MRI systems use the single radio frequency coil imaging. However over past several years research has increasingly focused on the concept of using arrays of mutually decoupled surface coils. These surface coil arrays can simultaneously acquire multiple images, resulting in an increase in the field of view. This thesis pursues the design and construction of a high impedance preamplifier with the goal of investigating the decoupling of a surface coil array in a 4.7T magnetic resonance system.

Dissertation (Ph.D.) -- Worcester Polytechnic Institute. / Keywords: rat brain; osmotic shock; blood brain barrier; manganese-enhanced MRI. Includes bibliographical references.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: algorithm; segmentation; rat atlas; MRI. Includes bibliographical references (p. 77-82).

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: Segmentation; ITK; CMake; Level set; Geodesic; FastMarching; Laplacian; Canny edge. Includes bibliographical references (p. 128-132).

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: stroke; animal models; magnetic resonance imaging; physiology; pathology. Includes bibliographical references (p. 80-85).

The research presented within this dissertation focused on two major areas of research: monitoring the response to single-dose radiotherapy in a RIF-1 tumor model and the role of cortical spreading depression in the evolution of ischemic stroke. For the research in the first half of this dissertation, quantitative MRI was performed to investigate the spatial correlation between the apparent diffusion coefficient (ADC), spin-spin relaxation times (T2), and proton density (M0) in murine radiation-induced fibrosarcoma (RIF-1) tumors following single-dose (1000cGy) radiotherapy using the k-means (KM) algorithm. An in-depth comparison between KM-derived volume estimates and conventional histology via the hematoxylin-eosin (H&E) staining procedure (for identification of viable tumor versus necrosis), as well as via hypoxic-inducible factor-1alpha (HIF-1alpha) immunohistochemistry (for identification of regions of hypoxia versus well-oxygenated tissue) was performed. The results of this study demonstrated that multispectral (MS) analysis provides: (1) an improved tissue segmentation method over results obtained from conventional single-parameter approaches, (2) subdivision based on the degree of necrosis, as well as delineation between well-oxygenated and hypoxic viable tissue, (3) good correlation with both H&E staining and HIF-1alpha immunohistochemistry, and (4) a method for monitoring the range of tissue viability as a function of time post-treatment, with the potential for predicting therapeutic efficacy. For the research in the second half of this dissertation, manganese-enhanced MRI (MEMRI) was employed for the characterization of both experimental and pathological cortical spreading depression (CSD). In order to determine the utility of manganese ions (Mn2+) as a marker for spreading depression (SD), experimental SD was elicited by chemical stimulation (KCl application to exposed rat cortex) and compared with control conditions. This study demonstrated that (1) Mn2+ is a more accurate marker for SD than DWI or T2* methods, (2) cortical restriction of MEMRI enhancement supports the contention that apical dendrites are necessary for SD propagation. (3) subcortical enhancement was a result of cortical-subcortical neuronal connectivity. Based on these results, preliminary experiments involving the study of SD in ischemia using Mn2+ were performed. Initial results indicate: (1) MEMRI may provide a method for estimating the likelihood of progression to infarction at acute timepoints post onset of stroke. These studies provide a foundation for further investigation into the role of SD in stroke, and the application of Mn2+ towards the design of therapeutic strategies targeting SD inhibition.

A common approach to segment an MRI dataset is to use a standard atlas to identify different regions of interest. Existing 2D atlases, prepared by freehand tracings of templates, are seldom complete for 3D volume segmentation. Although many of these atlases are prepared in graphics packages like Adobe Illustrator® (AI), which present the geometrical entities based on their mathematical description, the drawings are not numerically robust. This work presents an automatic conversion of graphical atlases suitable for further usage such as creation of a segmented 3D numerical atlas. The system begins with DXF (Drawing Exchange Format) files of individual atlas drawings. The drawing entities are mostly in cubic spline format. Each segment of the spline is reduced to polylines, which reduces the complexity of data. The system merges overlapping nodes and polylines to make the database of the drawing numerically integrated, i.e. each location within the drawing is referred by only one point, each line is uniquely defined by only two nodes, etc. Numerous integrity diagnostics are performed to eliminate duplicate or overlapping lines, extraneous markers, open-ended loops, etc. Numerically intact closed loops are formed using atlas labels as seed points. These loops specify the boundary and tissue type for each area. The final results preserve the original atlas with its 1272 different neuroanatomical regions which are complete, non-overlapping, contiguous sub-areas whose boundaries are composed of unique polylines