Document Detail

Improved Bloch-Siegert based B(1) mapping by reducing off-resonance shift.
MedLine Citation:
PMID:  23355474     Owner:  NLM     Status:  Publisher    
An MRI method based on the Bloch-Siegert (BS) shift phenomenon was recently proposed as a fast and precise way to map a radio frequency (RF) transmit field (B(1) (+) field). For MRI at high field, the mapping sensitivity of this approach was limited by tissue heating associated with a BS irradiation pulse. To mitigate this, we investigated the possibility of lowering the off-resonance frequency of this pulse since theoretical analysis indicated that the sensitivity of Bloch-Siegert based B(1) (+) mapping could be substantially improved when irradiating closer to resonance. Using optimized irradiation pulse shape and gradient crushers to minimize direct excitation effects, in vivo experiments on human brains at 7 T confirmed improved sensitivity with this approach. Improved sensitivity translated into an 80% reduction in B(1) (+) estimation errors without increasing tissue heating. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Qi Duan; Peter van Gelderen; Jeff Duyn
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2013-1-28
Journal Detail:
Title:  NMR in biomedicine     Volume:  -     ISSN:  1099-1492     ISO Abbreviation:  NMR Biomed     Publication Date:  2013 Jan 
Date Detail:
Created Date:  2013-1-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8915233     Medline TA:  NMR Biomed     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Copyright Information:
Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Advanced MRI Section, Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland, USA.
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