| The performance of interventional loopless MRI antennae at higher magnetic field strengths. | |
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MedLine Citation:
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PMID: 18561676 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Interventional, "loopless antenna" MRI detectors are currently limited to 1.5 T. This study investigates whether loopless antennae offer signal-to-noise ratio (SNR) and field-of-view (FOV) advantages at higher fields, and whether device heating can be controlled within safe limits. The absolute SNR performance of loopless antennae from 0.5 to 5 T is investigated both analytically, using electromagnetic (EM) dipole antenna theory, and numerically with the EM method of moments, and found to vary almost quadratically with field strength depending on the medium's electrical properties, the noise being dominated by direct sample conduction losses. The prediction is confirmed by measurements of the absolute SNR of low-loss loopless antennae fabricated for 1.5, 3, and 4.7 T, immersed in physiologically comparable saline. Gains of 3.8 +/- 0.2- and 9.7 +/- 0.3-fold in SNR, and approximately 10- and 50-fold gains in the useful FOV area are observed at 3 and 4.7 T, respectively, compared to 1.5 T. Heat testing of a 3 T biocompatible nitinol-antenna fabricated with a redesigned decoupling circuit shows maximum heating of approximately 1 degrees C for MRI operating at high MRI exposure levels. Experiments in the rabbit aorta confirm the SNR and FOV advantages of the 3 T antenna versus an equivalent commercial 1.5 T device in vivo. This work is the first to study the performance of experimental internal MRI detectors above 1.5 T. The large SNR and FOV gains realized present a major opportunity for high-resolution imaging of vascular pathology and MRI-guided intervention. |
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Authors:
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AbdEl-Monem M El-Sharkawy; Di Qian; Paul A Bottomley |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural |
Journal Detail:
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Title: Medical physics Volume: 35 ISSN: 0094-2405 ISO Abbreviation: Med Phys Publication Date: 2008 May |
Date Detail:
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Created Date: 2008-06-19 Completed Date: 2008-07-09 Revised Date: 2011-05-03 |
Medline Journal Info:
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Nlm Unique ID: 0425746 Medline TA: Med Phys Country: United States |
Other Details:
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Languages: eng Pagination: 1995-2006 Citation Subset: IM |
Affiliation:
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Division of MR Research, Department of Radiology, Johns Hopkins University, Baltimore, Maryland 21287, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Aorta / metabolism, pathology Biocompatible Materials / chemistry Electric Conductivity Electromagnetic Fields Equipment Design Hot Temperature Magnetic Resonance Imaging, Interventional / instrumentation*, methods* Magnetics Models, Statistical Models, Theoretical Rabbits Salts / chemistry Temperature |
| Grant Support | |
ID/Acronym/Agency:
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R01 EB007829-06A2/EB/NIBIB NIH HHS; R01 EB007829-09/EB/NIBIB NIH HHS; R01 HL090728/HL/NHLBI NIH HHS; R01 HL090728-01A1/HL/NHLBI NIH HHS; R01 RR015396-05/RR/NCRR NIH HHS; R01 RR15396/RR/NCRR NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Biocompatible Materials; 0/Salts |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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