Document Detail


Coaxial waveguide for travelling wave MRI at ultrahigh fields.
MedLine Citation:
PMID:  23023780     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
At high magnetic fields the performance of a volume-type body coil inside a human sized MR-scanner is influenced by the waveguide action of the scanner's bore. This can result in undesirable strong radio frequency fields (B 1+) outside the coil's target volume. A radio frequency (RF) transmit system, exploiting this waveguide action of the bore, is proposed in this work. A coaxial waveguide section is introduced between the antenna and the imaging region. It is shown that the coaxial waveguide has several advantages over the initially proposed travelling wave setup based on the cylindrical waveguide. First, a novel radio frequency matching principle (based on the transmission line impedance matching) is feasible with the coaxial waveguide achieving better radio frequency transmission characteristics, such as homogeneity and power efficiency of B 1+ field. In case of body torso imaging, the coaxial waveguide prevents unwanted specific absorptive rate (SAR) deposition outside the target region and thus, effectively decreases local peak SAR values by factor of 5. A 3-fold B 1+ gain in the prostate can be achieved with the coaxial waveguide in comparison with the initially proposed travelling wave setup. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Authors:
Anna Andreychenko; Hugo Kroeze; Dennis W J Klomp; Jan J W Lagendijk; Peter R Luijten; Cornelis A T van den Berg
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-9-28
Journal Detail:
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:  Magn Reson Med     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-10-1     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8505245     Medline TA:  Magn Reson Med     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Copyright © 2012 Wiley Periodicals, Inc.
Affiliation:
Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands; Department of Radiotherapy, University Medical Center Utrecht, Utrecht, the Netherlands. A.Andreychenko@umcutrecht.nl.
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