Imaging cerebrovascular health using 7T MRI
<p>Magnetic resonance imaging is a valuable clinical tool for the visualization of intracranial vasculature. Without exposing patients to ionizing radiation or intravenous contrasts, it can provide multi-modal structural information about the shape, structure, and function of the various vesse...
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| Other Authors: | |
| Format: | Thesis |
| Language: | English |
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2023
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| _version_ | 1797110150459293696 |
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| author | de Buck, MHS |
| author2 | Jezzard, P |
| author_facet | Jezzard, P de Buck, MHS |
| author_sort | de Buck, MHS |
| collection | OXFORD |
| description | <p>Magnetic resonance imaging is a valuable clinical tool for the visualization of intracranial vasculature. Without exposing patients to ionizing radiation or intravenous contrasts, it can provide multi-modal structural information about the shape, structure, and function of the various vessels involved in stroke and dementia. However, imaging methods are limited by the achieved contrasts and resolutions, as well as the required scan times.</p>
<p>Ultra-high field 7T MRI offers increased signal-to-noise ratio and desirable changes in relaxation parameters, therefore promising substantial improvements to existing neurovascular MRI approaches such as MR angiography (MRA) and MR vessel wall imaging (VWI). However, 7T MRI also introduces increased specific absorption rates and reduced homogeneity and extent of the transmit B1 field. Because of the latter, the first research chapter in this thesis (Chapter 3) studies the possibility to increase the extent of this 7T B1+ field into the feeding arteries in the neck using parallel transmission (pTx).</p>
<p>The second research chapter (Chapter 4) aims to improve the accelerated acquisition of high-resolution MRA using compressed sensing reconstruction. This facilitates the visualization of the small intracranial arteries which are involved in lacunar infarcts and vascular dementia, which can be achieved within clinical scan times.</p>
<p>The final parts of this thesis (Chapters 5-7) focus on a specific intracranial VWI sequence called DANTE-SPACE. A simulation framework for the sequence is first presented in Chapter 5. This framework includes various additional processes such as (pulsatile) tissue motion and B1+ variations to accurately represent the intra- and extra-vascular contrast mechanisms. The simulations are then used for the optimization and comparison of the T2-weighted DANTE-SPACE sequence at 3T, 7T without pTx, and 7T with pTx. The optimizations aim to maximize the contrast between both the blood within and the cerebrospinal fluid surrounding intracranial vessel walls, and the comparison between different field strengths provides a first quantitative indication of the added value of ultra- high field MRI for the DANTE-SPACE sequence.</p> |
| first_indexed | 2024-03-07T07:50:55Z |
| format | Thesis |
| id | oxford-uuid:2e60ac9f-0028-409a-87ff-9811aea67c48 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:50:55Z |
| publishDate | 2023 |
| record_format | dspace |
| spelling | oxford-uuid:2e60ac9f-0028-409a-87ff-9811aea67c482023-07-13T09:36:20ZImaging cerebrovascular health using 7T MRIThesishttp://purl.org/coar/resource_type/c_db06uuid:2e60ac9f-0028-409a-87ff-9811aea67c48Magnetic resonance imagingEnglishHyrax Deposit2023de Buck, MHSJezzard, PHess, A<p>Magnetic resonance imaging is a valuable clinical tool for the visualization of intracranial vasculature. Without exposing patients to ionizing radiation or intravenous contrasts, it can provide multi-modal structural information about the shape, structure, and function of the various vessels involved in stroke and dementia. However, imaging methods are limited by the achieved contrasts and resolutions, as well as the required scan times.</p> <p>Ultra-high field 7T MRI offers increased signal-to-noise ratio and desirable changes in relaxation parameters, therefore promising substantial improvements to existing neurovascular MRI approaches such as MR angiography (MRA) and MR vessel wall imaging (VWI). However, 7T MRI also introduces increased specific absorption rates and reduced homogeneity and extent of the transmit B1 field. Because of the latter, the first research chapter in this thesis (Chapter 3) studies the possibility to increase the extent of this 7T B1+ field into the feeding arteries in the neck using parallel transmission (pTx).</p> <p>The second research chapter (Chapter 4) aims to improve the accelerated acquisition of high-resolution MRA using compressed sensing reconstruction. This facilitates the visualization of the small intracranial arteries which are involved in lacunar infarcts and vascular dementia, which can be achieved within clinical scan times.</p> <p>The final parts of this thesis (Chapters 5-7) focus on a specific intracranial VWI sequence called DANTE-SPACE. A simulation framework for the sequence is first presented in Chapter 5. This framework includes various additional processes such as (pulsatile) tissue motion and B1+ variations to accurately represent the intra- and extra-vascular contrast mechanisms. The simulations are then used for the optimization and comparison of the T2-weighted DANTE-SPACE sequence at 3T, 7T without pTx, and 7T with pTx. The optimizations aim to maximize the contrast between both the blood within and the cerebrospinal fluid surrounding intracranial vessel walls, and the comparison between different field strengths provides a first quantitative indication of the added value of ultra- high field MRI for the DANTE-SPACE sequence.</p> |
| spellingShingle | Magnetic resonance imaging de Buck, MHS Imaging cerebrovascular health using 7T MRI |
| title | Imaging cerebrovascular health using 7T MRI |
| title_full | Imaging cerebrovascular health using 7T MRI |
| title_fullStr | Imaging cerebrovascular health using 7T MRI |
| title_full_unstemmed | Imaging cerebrovascular health using 7T MRI |
| title_short | Imaging cerebrovascular health using 7T MRI |
| title_sort | imaging cerebrovascular health using 7t mri |
| topic | Magnetic resonance imaging |
| work_keys_str_mv | AT debuckmhs imagingcerebrovascularhealthusing7tmri |