This item is under embargo and not available online per the author's request. For access information, please visit http://libanswers.wustl.edu/faq/5640.

ORCID

http://orcid.org/0000-0003-1511-1515

Date of Award

Summer 8-15-2021

Author's School

Graduate School of Arts and Sciences

Author's Department

Biology & Biomedical Sciences (Neurosciences)

Degree Name

Doctor of Philosophy (PhD)

Degree Type

Dissertation

Abstract

Diffusion weighted imaging (DWI) is used to non-invasively infer and characterize the structure and integrity of the brain’s white matter fibers. Individual-specific precision diffusion imaging can identify additional organizational detail important for understanding basic brain connectivity and for advancing clinical applications of DWI in neuromodulation and neurosurgical planning. The reliability of individual specific DWI and data requirements for various analytic methodologies must first be systematically assessed. The reliability and accuracy of precision diffusion imaging was evaluated as a function of data quantity and analysis method, using both simulations and highly sampled individual-specific data (Chapter 2). Parameter estimation methods that allowed for crossing fibers were found to estimate excess fibers when data amounts were insufficient and when the data did not match the model priors. Once individual-specific precision diffusion imaging standards were established in single tensor and crossing-fiber models, clinical and research applications were tested. Precision diffusion tensor imaging was acquired pre- and post-hemispherotomy, a surgical intervention used in the treatment of drug-resistant focal epilepsy (Chapter 3). Lingering inter-hemispheric association fibers were estimated in the genu of the corpus callosum of an individual who had recurrent seizures after the surgical intervention, fibers that were no longer detected after a follow-up surgery. This provides proof-of-principle for clinical precision diffusion imaging to aid in the evaluation of white matter changes following neurosurgical interventions. The second application of precision diffusion imaging was in individual-specific white matter connectivity changes due to disuse, where the dominant upper extremity of three healthy adults was casted for two weeks (Chapter 4). Despite the powerful experimental intervention that had large changes in resting state functional connectivity between left and right motor networks, precision diffusion imaging found no significant changes in the local white matter microstructure, highlighting the stability of adult white matter tracts absent injury or surgery. This thesis research initializes the standards and requirements for individual-specific precision diffusion imaging in healthy adults and provides proof-of-principle for clinical applications.

Language

English (en)

Chair and Committee

Nico U. Dosenbach

Committee Members

Deanna M. Barch, Evan M. Gordon, Tamara G. Hershey, Joshua S. Shimony,

Available for download on Saturday, August 19, 2023

Share

COinS