Consideration of magnetically-induced and conservative electric fields within a loaded gradient coil

Weihua Mao, Blaine A. Chronik, Rebecca E. Feldman, Michael B. Smith, Christopher M. Collins

Research output: Contribution to journalArticlepeer-review


We present a method to calculate the electric (E)-fields within and surrounding a human body in a gradient coil, including E-fields induced by the changing magnetic fields and "conservative" E-fields originating with the scalar electrical potential in the coil windings. In agreement with previous numerical calculations, it is shown that magnetically-induced E-fields within the human body show no real concentration near the surface of the body, where nerve stimulation most often occurs. Both the magnetically-induced and conservative E-fields are shown to be considerably stronger just outside the human body than inside it, and under some circumstances the conservative E-fields just outside the body can be much larger than the magnetically-induced E-fields there. The order of gradient winding and the presence of conductive RF shield can greatly affect the conservative E-field distribution in these cases. Though the E-fields against the outer surface of the body are not commonly considered, understanding gradient E-fields may be important for reasons other than peripheral nerve stimulation (PNS), such as potential interaction with electrical equipment.

Original languageEnglish (US)
Pages (from-to)1424-1432
Number of pages9
JournalMagnetic resonance in medicine
Issue number6
StatePublished - Jun 2006
Externally publishedYes


  • Calculations
  • Electric fields
  • Gradient coil
  • Peripheral nerve stimulation
  • Scalar potential

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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