Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI
<p><strong>Purpose: </strong>The purpose of this work is to validate a simple and versatile integrated variable flip angle (VFA) method for mapping B<sub>1</sub> in hyperpolarized MRI, which can be used to correct signal variations due to coil inhomoge...
| Main Authors: | , , , , , , , , , , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
Wiley
2024
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| _version_ | 1826317630523310080 |
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| author | Yeung, K Ng Lik, K McGing, JJ Axford, A Birkhoelzer, S Shinozaki, A Ricchi, M Scambelluri, N Zaccagna, F Mills, R Lewis, AJM Rayner, JJ Ravetz, Z MacIntyre, A Rider, OJ Schulte, RF Gleeson, FV Tyler, DJ Grist, JT |
| author_facet | Yeung, K Ng Lik, K McGing, JJ Axford, A Birkhoelzer, S Shinozaki, A Ricchi, M Scambelluri, N Zaccagna, F Mills, R Lewis, AJM Rayner, JJ Ravetz, Z MacIntyre, A Rider, OJ Schulte, RF Gleeson, FV Tyler, DJ Grist, JT |
| author_sort | Yeung, K |
| collection | OXFORD |
| description | <p><strong>Purpose: </strong>The purpose of this work is to validate a simple and versatile integrated variable flip angle (VFA) method for mapping B<sub>1</sub> in hyperpolarized MRI, which can be used to correct signal variations due to coil inhomogeneity.</p>
<p><strong>Theory and Methods: </strong>Simulations were run to assess performance of the VFA B<sub>1</sub> mapping method compared to the currently used constant flip angle (CFA) approach. Simulation results were used to inform the design of VFA sequences, validated in four volunteers for hyperpolarized xenon-129 imaging of the lungs and another four volunteers for hyperpolarized carbon-13 imaging of the human brain. B<sub>1</sub> maps obtained were used to correct transmit and receive inhomogeneity in the images.</p>
<p><strong>Results: </strong>Simulations showed improved performance of the VFA approach over the CFA approach with reduced sensitivity to T<sub>1</sub>. For xenon-129, the B<sub>1</sub> maps accurately reflected the variation of signal depolarization, but in some cases could not be used to correct for coil receive inhomogeneity due to a lack of transmit-receive reciprocity resulting from suboptimal coil positioning. For carbon-13, the B<sub>1</sub> maps showed good agreement with a separately acquired B<sub>1</sub> map of a phantom and were effectively used to correct coil-induced signal inhomogeneity.</p>
<p><strong>Conclusion: </strong>A simple, versatile, and effective VFA B<sub>1</sub> mapping method was implemented and evaluated. Inclusion of the B<sub>1</sub> mapping method in hyperpolarized imaging studies can enable more robust signal quantification.</p> |
| first_indexed | 2024-12-09T03:37:32Z |
| format | Journal article |
| id | oxford-uuid:91591ab3-8bf8-4cdd-9dcb-a6ca2b296376 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2025-03-11T16:56:57Z |
| publishDate | 2024 |
| publisher | Wiley |
| record_format | dspace |
| spelling | oxford-uuid:91591ab3-8bf8-4cdd-9dcb-a6ca2b2963762025-02-28T09:36:34ZEvaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRIJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:91591ab3-8bf8-4cdd-9dcb-a6ca2b296376EnglishSymplectic ElementsWiley2024Yeung, KNg Lik, KMcGing, JJAxford, ABirkhoelzer, SShinozaki, ARicchi, MScambelluri, NZaccagna, FMills, RLewis, AJMRayner, JJRavetz, ZMacIntyre, ARider, OJSchulte, RFGleeson, FVTyler, DJGrist, JT<p><strong>Purpose: </strong>The purpose of this work is to validate a simple and versatile integrated variable flip angle (VFA) method for mapping B<sub>1</sub> in hyperpolarized MRI, which can be used to correct signal variations due to coil inhomogeneity.</p> <p><strong>Theory and Methods: </strong>Simulations were run to assess performance of the VFA B<sub>1</sub> mapping method compared to the currently used constant flip angle (CFA) approach. Simulation results were used to inform the design of VFA sequences, validated in four volunteers for hyperpolarized xenon-129 imaging of the lungs and another four volunteers for hyperpolarized carbon-13 imaging of the human brain. B<sub>1</sub> maps obtained were used to correct transmit and receive inhomogeneity in the images.</p> <p><strong>Results: </strong>Simulations showed improved performance of the VFA approach over the CFA approach with reduced sensitivity to T<sub>1</sub>. For xenon-129, the B<sub>1</sub> maps accurately reflected the variation of signal depolarization, but in some cases could not be used to correct for coil receive inhomogeneity due to a lack of transmit-receive reciprocity resulting from suboptimal coil positioning. For carbon-13, the B<sub>1</sub> maps showed good agreement with a separately acquired B<sub>1</sub> map of a phantom and were effectively used to correct coil-induced signal inhomogeneity.</p> <p><strong>Conclusion: </strong>A simple, versatile, and effective VFA B<sub>1</sub> mapping method was implemented and evaluated. Inclusion of the B<sub>1</sub> mapping method in hyperpolarized imaging studies can enable more robust signal quantification.</p> |
| spellingShingle | Yeung, K Ng Lik, K McGing, JJ Axford, A Birkhoelzer, S Shinozaki, A Ricchi, M Scambelluri, N Zaccagna, F Mills, R Lewis, AJM Rayner, JJ Ravetz, Z MacIntyre, A Rider, OJ Schulte, RF Gleeson, FV Tyler, DJ Grist, JT Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI |
| title | Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI |
| title_full | Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI |
| title_fullStr | Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI |
| title_full_unstemmed | Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI |
| title_short | Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI |
| title_sort | evaluation of an integrated variable flip angle protocol to estimate coil b1 for hyperpolarized mri |
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