| Autor: |
Recoskie BJ; Department of Medical Biophysics, The University of Western Ontario, London, Ontario, Canada., Scholl TJ, Chronik BA |
| Jazyk: |
angličtina |
| Zdroj: |
Physics in medicine and biology [Phys Med Biol] 2009 Oct 07; Vol. 54 (19), pp. 5965-79. Date of Electronic Publication: 2009 Sep 17. |
| DOI: |
10.1088/0031-9155/54/19/020 |
| Abstrakt: |
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. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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