A programmable pre-emphasis system

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

doi:10.1002/mrm.1910400313

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 journal › Article › peer-review

34 Scopus citations

Abstract

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 language	English
Pages (from-to)	427-431
Number of pages	5
Journal	Magnetic resonance in medicine
Volume	40
Issue number	3
DOIs	https://doi.org/10.1002/mrm.1910400313
State	Published - Sep 1998

Keywords

Eddy current
Gradient compensation
Pre-emphasis
Time constant

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10.1002/mrm.1910400313

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title = "A programmable pre-emphasis system",

abstract = "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.",

keywords = "Eddy current, Gradient compensation, Pre-emphasis, Time constant",

author = "Gach, {H. Michael} and Lowe, {Irving J.} and Madio, {David P.} and Arvind Caprihan and Altobelli, {Stephen A.} and Kuethe, {Dean O.} and Eiichi Fukushima",

year = "1998",

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T1 - A programmable pre-emphasis system

AU - Gach, H. Michael

AU - Lowe, Irving J.

AU - Madio, David P.

AU - Caprihan, Arvind

AU - Altobelli, Stephen A.

AU - Kuethe, Dean O.

AU - Fukushima, Eiichi

PY - 1998/9

Y1 - 1998/9

N2 - 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.

AB - 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.

KW - Eddy current

KW - Gradient compensation

KW - Pre-emphasis

KW - Time constant

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DO - 10.1002/mrm.1910400313

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VL - 40

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JO - Magnetic resonance in medicine

JF - Magnetic resonance in medicine

IS - 3

ER -

A programmable pre-emphasis system

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Keywords

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