{"title":"在3t和7t时使用下行核磁共振成像（MRSI）在人脑中的酰胺映射。","authors":"İpek Özdemir, Semra Etyemez, Peter B. Barker","doi":"10.1002/mrm.30458","DOIUrl":null,"url":null,"abstract":"<div>\n \n \n <section>\n \n <h3> Purpose</h3>\n \n <p>To quantitatively compare signal-to-noise ratios (SNRs), linewidth values, and Cramér-Rao lower bounds (CRLBs) for amide resonances in the human brain measured at 3T and 7T using downfield MR spectroscopic imaging (DF-MRSI).</p>\n </section>\n \n <section>\n \n <h3> Methods</h3>\n \n <p>Seven normal volunteers (25–52 years, 5 female) were imaged using Philips 3T Elition and 7T Achieva scanners. Both systems have 32-channel receive head coils and 16-channel local shim arrays (MRShim GmbH) in addition to high-order spherical harmonic shims. Three-dimensional DF-MRSI data were collected using a previously developed pulse sequence with spectral-spatial excitation and frequency-selective refocusing pulses. Matched imaging protocols on both field strengths were applied to achieve a nominal voxel size of 7 × 7 × 15 mm in a scan time of 10.6 min. Spectral analysis was performed using the “LCModel” software package. SNR and CRLB values (%) were compared between 3T and 7T data using univariate general linear models.</p>\n </section>\n \n <section>\n \n <h3> Results</h3>\n \n <p>Significantly increased amide SNR and decreased CRLB values (<i>p < 0.05</i>) were found at 7T. Averaged over all brain regions, SNR was 2.9 ± 1.1 at 3T and 5.4 ± 1.5 at 7T, and CRLBs were 11.4 ± 3.9 and 4.9 ± 1.5 respectively. 7T MRI and amide images did show some regional signal dropoff due to transmit B<sub>1</sub> inhomogeneity, however.</p>\n </section>\n \n <section>\n \n <h3> Conclusion</h3>\n \n <p>Three-dimensional DF-MRSI at 7T showed 86% increased SNR and 57% decreased CRLB values compared with 3T, confirming the expected improvements at higher field. Improvements are probably due to multiple factors, including higher magnetization at 7T, the shorter minimum echo time available, among others.</p>\n </section>\n </div>","PeriodicalId":18065,"journal":{"name":"Magnetic Resonance in Medicine","volume":"93 6","pages":"2254-2262"},"PeriodicalIF":3.0000,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Amide mapping in the human brain using downfield MRSI at 3 T and 7 T\",\"authors\":\"İpek Özdemir, Semra Etyemez, Peter B. Barker\",\"doi\":\"10.1002/mrm.30458\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div>\\n \\n \\n <section>\\n \\n <h3> Purpose</h3>\\n \\n <p>To quantitatively compare signal-to-noise ratios (SNRs), linewidth values, and Cramér-Rao lower bounds (CRLBs) for amide resonances in the human brain measured at 3T and 7T using downfield MR spectroscopic imaging (DF-MRSI).</p>\\n </section>\\n \\n <section>\\n \\n <h3> Methods</h3>\\n \\n <p>Seven normal volunteers (25–52 years, 5 female) were imaged using Philips 3T Elition and 7T Achieva scanners. Both systems have 32-channel receive head coils and 16-channel local shim arrays (MRShim GmbH) in addition to high-order spherical harmonic shims. Three-dimensional DF-MRSI data were collected using a previously developed pulse sequence with spectral-spatial excitation and frequency-selective refocusing pulses. Matched imaging protocols on both field strengths were applied to achieve a nominal voxel size of 7 × 7 × 15 mm in a scan time of 10.6 min. Spectral analysis was performed using the “LCModel” software package. SNR and CRLB values (%) were compared between 3T and 7T data using univariate general linear models.</p>\\n </section>\\n \\n <section>\\n \\n <h3> Results</h3>\\n \\n <p>Significantly increased amide SNR and decreased CRLB values (<i>p < 0.05</i>) were found at 7T. Averaged over all brain regions, SNR was 2.9 ± 1.1 at 3T and 5.4 ± 1.5 at 7T, and CRLBs were 11.4 ± 3.9 and 4.9 ± 1.5 respectively. 7T MRI and amide images did show some regional signal dropoff due to transmit B<sub>1</sub> inhomogeneity, however.</p>\\n </section>\\n \\n <section>\\n \\n <h3> Conclusion</h3>\\n \\n <p>Three-dimensional DF-MRSI at 7T showed 86% increased SNR and 57% decreased CRLB values compared with 3T, confirming the expected improvements at higher field. Improvements are probably due to multiple factors, including higher magnetization at 7T, the shorter minimum echo time available, among others.</p>\\n </section>\\n </div>\",\"PeriodicalId\":18065,\"journal\":{\"name\":\"Magnetic Resonance in Medicine\",\"volume\":\"93 6\",\"pages\":\"2254-2262\"},\"PeriodicalIF\":3.0000,\"publicationDate\":\"2025-02-18\",\"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://onlinelibrary.wiley.com/doi/10.1002/mrm.30458\",\"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://onlinelibrary.wiley.com/doi/10.1002/mrm.30458","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}
Amide mapping in the human brain using downfield MRSI at 3 T and 7 T
Purpose
To quantitatively compare signal-to-noise ratios (SNRs), linewidth values, and Cramér-Rao lower bounds (CRLBs) for amide resonances in the human brain measured at 3T and 7T using downfield MR spectroscopic imaging (DF-MRSI).
Methods
Seven normal volunteers (25–52 years, 5 female) were imaged using Philips 3T Elition and 7T Achieva scanners. Both systems have 32-channel receive head coils and 16-channel local shim arrays (MRShim GmbH) in addition to high-order spherical harmonic shims. Three-dimensional DF-MRSI data were collected using a previously developed pulse sequence with spectral-spatial excitation and frequency-selective refocusing pulses. Matched imaging protocols on both field strengths were applied to achieve a nominal voxel size of 7 × 7 × 15 mm in a scan time of 10.6 min. Spectral analysis was performed using the “LCModel” software package. SNR and CRLB values (%) were compared between 3T and 7T data using univariate general linear models.
Results
Significantly increased amide SNR and decreased CRLB values (p < 0.05) were found at 7T. Averaged over all brain regions, SNR was 2.9 ± 1.1 at 3T and 5.4 ± 1.5 at 7T, and CRLBs were 11.4 ± 3.9 and 4.9 ± 1.5 respectively. 7T MRI and amide images did show some regional signal dropoff due to transmit B1 inhomogeneity, however.
Conclusion
Three-dimensional DF-MRSI at 7T showed 86% increased SNR and 57% decreased CRLB values compared with 3T, confirming the expected improvements at higher field. Improvements are probably due to multiple factors, including higher magnetization at 7T, the shorter minimum echo time available, among others.
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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