Methods for imaging brain function using BOLD and viscoelastic contrast
Abstract/Contents
- Abstract
- Modern functional neuroimaging techniques have greatly advanced the field of neuroscience, with different modalities targeting distinctive aspects of brain physiology, functional architecture, and dynamics. Specifically, functional magnetic resonance imaging (fMRI) uses blood-oxygen-level dependent (BOLD) contrast to study the underlying neurovascular coupling. One of the limitations of fMRI is its low temporal resolution for collecting the time series data, which has been partially addressed in human brain imaging with the development of parallel imaging. However, parallel imaging is not attainable in some cases due to infeasibility of high-density phased-array coils. To overcome this, we developed an approach to accelerate fMRI acquisition without parallel imaging by adapting phase-offset multiplanar (POMP) imaging to echo-planar imaging (EPI), using gradient blips inspired by CAIPI to shift each of the simultaneously excited slices into different regions of an extended field-of-view, such that there is no aliasing of the simultaneously excited slices. Since fMRI only provides an indirect measure of neuronal activity, the neuroimaging community has been searching for different contrast mechanisms that can further elucidate the process of neuronal signaling. A new and emerging functional neuroimaging technique, functional magnetic resonance elastography (fMRE), measures changes in brain stiffness due to neural activity. We introduce a novel multi-modal method, fMRI-fMRE, to observe this neuromechanical coupling mechanism in the human brain. The novelty in our approach comes from utilizing a time series acquisition, similar in concept to that employed in fMRI, where the magnitude and phase information from the time series are processed and analyzed separately to arrive at both fMRI and fMRE activation maps. Since our simultaneous fMRI-fMRE method is both multi-modal and concurrent, it allows for comparison of the spatially localized BOLD and stiffness changes within the same scan, removing confounds inherent in separately acquired scans. Motivated by early reports that fMRE could provide an order of magnitude increase in temporal resolution, we initially tested this method with partial-brain scans, demonstrating stiffness increases in the visual cortex in response to visual stimuli. Subsequently, we extended the fMRI-fMRE method to whole-brain imaging to explore global brain stiffness dynamics in response to both visual and motor-planning tasks. The end of my thesis journey coincided with the COVID-19 pandemic, which led to widespread incidence of infection. To diminish the risk of virus transmission, many research MRI scanning facilities started to require continuous facial covering by scan subjects. Since mask-wearing can slightly change the carbon dioxide concentration in inspired air, and carbon dioxide is a potent vasodilator, the final project in this thesis investigates the effect of facial covering on fMRI BOLD signal.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2021; ©2021 |
| Publication date | 2021; 2021 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Lan, Patricia Sheu |
|---|---|
| Degree supervisor | Glover, Gary H |
| Thesis advisor | Glover, Gary H |
| Thesis advisor | Daniel, Bruce (Bruce Lewis) |
| Thesis advisor | Pauly, John (John M.) |
| Degree committee member | Daniel, Bruce (Bruce Lewis) |
| Degree committee member | Pauly, John (John M.) |
| Associated with | Stanford University, Department of Bioengineering |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Patricia Sheu Lan. |
|---|---|
| Note | Submitted to the Department of Bioengineering. |
| Thesis | Thesis Ph.D. Stanford University 2021. |
| Location | https://purl.stanford.edu/qj563px7413 |
Access conditions
- Copyright
- © 2021 by Patricia Sheu Lan
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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