Undergraduate Honors Theses

Thesis Defended

Spring 2019

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Psychology & Neuroscience

First Advisor

John A. Thompson, Ph.D.

Second Advisor

Akira Miyake, Ph.D.

Third Advisor

Nancy Guild, Ph.D.

Fourth Advisor

Alison Vigers, Ph.D.

Abstract

Gliomas account for 26.5% of all primary central nervous system tumors. Histopathological observation has been the gold standard for diagnosing and studying gliomas, however, this method has several limitations. Recent studies have used diffusion tensor imaging (DTI) to extract white matter fibers and the diffusion coefficients derived from the magnetic resonance processing to provide non-invasive insights into the extent of tumor invasion, axonal integrity, and pathophysiological differentiation of glioma from metastasis. This work extends the capabilities of DTI by examining whether a tract-based analysis can improve non-invasive localization of tumor impact on white matter integrity. This study also examines the anatomical shift gliomas may have on white matter by implementing a structural connectometry analysis. This study retrospectively analyzed preoperative MRIs highlighting pathological tissue through contrast enhancement and DTI scans of subjects that were biopsy confirmed to have either high or low-grade glioma. Whole-brain-seeding, required for structural connectometry and reconstruction of specific white matter pathways, was derived through DSI Studio’s deterministic Euler Streamline Algorithm. Two major white matter pathways, the corticospinal tract and superior longitudinal fasciculus, were reconstructed for along-tract-analysis by applying atlas-based regions of interest. Ipsilesional and contralesional hemisphere tractography were used to compute within-subject comparisons for all analyses. Diffusion parameters indicated higher levels of white matter degradation in the ipsilesional hemisphere. Novel application of along-tract-analysis revealed tracts traversing the tumor region showed significant white matter degradation which decreased with distance from the tumor. Furthermore, connectometry revealed a shift in anatomical connections of the ipsilesional compared to the contralesional hemisphere.

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