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PubMed · 9727946

A programmable pre-emphasis system.

H M Gach·I J Lowe·D P Madio·A Caprihan·S A Altobelli·D O Kuethe·E Fukushima
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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.

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ArtifactsComputer SystemsHumansImage EnhancementMagnetic Resonance ImagingSoftwareJournal ArticleResearch Support, U.S. Gov't, P.H.S.

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H M Gach, I J Lowe, D P Madio, A Caprihan, S A Altobelli, D O Kuethe, E Fukushima. 1998. A programmable pre-emphasis system.. https://doi.org/10.1002/mrm.1910400313

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