| Maximum efficiency radiofrequency shimming: Theory and initial application for hip imaging at 7 tesla. | |
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MedLine Citation:
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PMID: 22714835 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Radiofrequency shimming with multiple channel excitation has been proposed to increase the transverse magnetic field uniformity and reduce specific absorption rate at high magnetic field strengths (≥7 T) where high-frequency effects can make traditional single channel volume coils unsuitable for transmission. In the case of deep anatomic regions and power-demanding pulse sequences, optimization of transmit efficiency may be a more critical requirement than homogeneity per se. This work introduces a novel method to maximize transmit efficiency using multiple channel excitation and radiofrequency shimming. Shimming weights are calculated in order to obtain the lowest possible net radiofrequency power deposition into the subject for a given transverse magnetic field strength. The method was demonstrated in imaging studies of articular cartilage of the hip joint at 7 T. We show that the new radiofrequency shimming method can enable reduction in power deposition while maintaining an average flip angle or adiabatic condition in the hip cartilage. Building upon the improved shimming, we further show that the signal-to-noise ratio in hip cartilage at 7 T can be substantially greater than that at 3 T, illustrating the potential benefits of high field hip imaging. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc. |
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Authors:
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Cem Murat Deniz; Ryan Brown; Riccardo Lattanzi; Leeor Alon; Daniel K Sodickson; Yudong Zhu |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2012-6-19 |
Journal Detail:
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Title: Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine / Society of Magnetic Resonance in Medicine Volume: - ISSN: 1522-2594 ISO Abbreviation: - Publication Date: 2012 Jun |
Date Detail:
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Created Date: 2012-6-20 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8505245 Medline TA: Magn Reson Med Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2012 Wiley Periodicals, Inc. |
Affiliation:
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Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University School of Medicine, New York, New York, USA; Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, New York, USA. cemmurat.deniz@nyumc.org. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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