Document Detail


The discrepancy between human peripheral nerve chronaxie times as measured using magnetic and electric field stimuli: the relevance to MRI gradient coil safety.
MedLine Citation:
PMID:  19759411     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Peripheral nerve stimulation (PNS) resulting from electric fields induced from the rapidly changing magnetic fields of gradient coils is a concern in MRI. Nerves exposed to either electric fields or changing magnetic fields would be expected to display consistent threshold characteristics, motivating the direct application of electric field exposure criteria from the literature to guide the development of gradient magnetic field exposure criteria for MRI. The consistency of electric and magnetic field exposures was tested by comparing chronaxie times for electric and magnetic PNS curves for 22 healthy human subjects. Electric and magnetic stimulation thresholds were measured for exposure of the forearm using both surface electrodes and a figure-eight magnetic coil, respectively. The average chronaxie times for the electric and magnetic field conditions were 109 +/- 11 micros and 651 +/- 53 micros (+/-SE), respectively. We do not propose that these results call into question the basic mechanism, namely that rapidly switched gradient magnetic fields induce electric fields in human tissues, resulting in PNS. However, this result does motivate us to suggest that special care must be taken when using electric field exposure data from the literature to set gradient coil PNS safety standards in MRI.
Authors:
Bryan J Recoskie; Timothy J Scholl; Blaine A Chronik
Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2009-09-17
Journal Detail:
Title:  Physics in medicine and biology     Volume:  54     ISSN:  1361-6560     ISO Abbreviation:  Phys Med Biol     Publication Date:  2009 Oct 
Date Detail:
Created Date:  2009-09-23     Completed Date:  2010-01-15     Revised Date:  2010-02-09    
Medline Journal Info:
Nlm Unique ID:  0401220     Medline TA:  Phys Med Biol     Country:  England    
Other Details:
Languages:  eng     Pagination:  5965-79     Citation Subset:  IM    
Affiliation:
Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada.
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MeSH Terms
Descriptor/Qualifier:
Chronaxy*
Electricity*
Equipment Safety
Female
Humans
Magnetic Resonance Imaging / adverse effects*,  methods
Magnetics*
Male
Peripheral Nerves / physiology*
Time Factors
Young Adult
Grant Support
ID/Acronym/Agency:
EB01519-03/EB/NIBIB NIH HHS
Comments/Corrections
Comment In:
Phys Med Biol. 2010 Feb 21;55(4):L5-8   [PMID:  20124652 ]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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