A programmable pre-emphasis system

H. Michael Gach, Irving J. Lowe, David P. Madio, Arvind Caprihan, Stephen A. Altobelli, Dean O. Kuethe, Eiichi Fukushima

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


MRI systems often use magnetic field gradient and shim pulse-shaping networks (pre-emphasis) to correct for magnetic field distortions caused by eddy currents. A pre-emphasis system that uses up to 16 fixed resistor- capacitor (RC) time constants per channel with programmable amplitude coefficients is described. The magnetic fields induced by the pre-emphasis RC time constants serve as a set of basis functions for compensating eddy- current fields induced by the gradient set. The resultant time-varying magnetic field gradient accurately reflects the gradient specified by the pulse programmer. Reductions in eddy-current fields are demonstrated for actively shielded and unshielded gradient sets.

Original languageEnglish
Pages (from-to)427-431
Number of pages5
JournalMagnetic resonance in medicine
Issue number3
StatePublished - Sep 1998


  • Eddy current
  • Gradient compensation
  • Pre-emphasis
  • Time constant


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