Kylie Yeung, Kher Lik Ng, Jordan J McGing, Aaron Axford, Sarah Birkhoelzer, Ayaka Shinozaki, Mattia Ricchi, Noemi Sgambelluri, Fulvio Zaccagna, Rebecca Mills, Andrew J M Lewis, Jennifer J Rayner, Zack Ravetz, Lise Berner, Kenneth Jacob, Anthony McIntyre, Marianne Durrant, Oliver J Rider, Rolf F Schulte, Fergus V Gleeson, Damian J Tyler, James T Grist
{"title":"评估用于估算超极化磁共振成像线圈 B1 的综合可变翻转角方案。","authors":"Kylie Yeung, Kher Lik Ng, Jordan J McGing, Aaron Axford, Sarah Birkhoelzer, Ayaka Shinozaki, Mattia Ricchi, Noemi Sgambelluri, Fulvio Zaccagna, Rebecca Mills, Andrew J M Lewis, Jennifer J Rayner, Zack Ravetz, Lise Berner, Kenneth Jacob, Anthony McIntyre, Marianne Durrant, Oliver J Rider, Rolf F Schulte, Fergus V Gleeson, Damian J Tyler, James T Grist","doi":"10.1002/mrm.30378","DOIUrl":null,"url":null,"abstract":"<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>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":" ","pages":""},"PeriodicalIF":3.0000,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Evaluation of an integrated variable flip angle protocol to estimate coil B<sub>1</sub> for hyperpolarized MRI.\",\"authors\":\"Kylie Yeung, Kher Lik Ng, Jordan J McGing, Aaron Axford, Sarah Birkhoelzer, Ayaka Shinozaki, Mattia Ricchi, Noemi Sgambelluri, Fulvio Zaccagna, Rebecca Mills, Andrew J M Lewis, Jennifer J Rayner, Zack Ravetz, Lise Berner, Kenneth Jacob, Anthony McIntyre, Marianne Durrant, Oliver J Rider, Rolf F Schulte, Fergus V Gleeson, Damian J Tyler, James T Grist\",\"doi\":\"10.1002/mrm.30378\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<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>\",\"PeriodicalId\":18065,\"journal\":{\"name\":\"Magnetic Resonance in Medicine\",\"volume\":\" \",\"pages\":\"\"},\"PeriodicalIF\":3.0000,\"publicationDate\":\"2024-11-17\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Magnetic Resonance in Medicine\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1002/mrm.30378\",\"RegionNum\":3,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Magnetic Resonance in Medicine","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1002/mrm.30378","RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"RADIOLOGY, NUCLEAR MEDICINE & MEDICAL IMAGING","Score":null,"Total":0}
Evaluation of an integrated variable flip angle protocol to estimate coil B1 for hyperpolarized MRI.
Purpose: The purpose of this work is to validate a simple and versatile integrated variable flip angle (VFA) method for mapping B1 in hyperpolarized MRI, which can be used to correct signal variations due to coil inhomogeneity.
Theory and methods: Simulations were run to assess performance of the VFA B1 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. B1 maps obtained were used to correct transmit and receive inhomogeneity in the images.
Results: Simulations showed improved performance of the VFA approach over the CFA approach with reduced sensitivity to T1. For xenon-129, the B1 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 B1 maps showed good agreement with a separately acquired B1 map of a phantom and were effectively used to correct coil-induced signal inhomogeneity.
Conclusion: A simple, versatile, and effective VFA B1 mapping method was implemented and evaluated. Inclusion of the B1 mapping method in hyperpolarized imaging studies can enable more robust signal quantification.
期刊介绍：
Magnetic Resonance in Medicine (Magn Reson Med) is an international journal devoted to the publication of original investigations concerned with all aspects of the development and use of nuclear magnetic resonance and electron paramagnetic resonance techniques for medical applications. Reports of original investigations in the areas of mathematics, computing, engineering, physics, biophysics, chemistry, biochemistry, and physiology directly relevant to magnetic resonance will be accepted, as well as methodology-oriented clinical studies.
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