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Gradient characterization using a Fourier‐transform technique
Author(s) -
Alley Marcus T.,
Glover Gary H.,
Pelc Norbert J.
Publication year - 1998
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910390411
Subject(s) - eddy current , waveform , fourier transform , fourier analysis , measure (data warehouse) , impulse response , residual , computer science , impulse (physics) , k space , parameterized complexity , algorithm , physics , nuclear magnetic resonance , computational physics , mathematical analysis , mathematics , voltage , quantum mechanics , database
Abstract This paper describes a technique for characterizing the gradient subsystem of a magnetic resonance (MR) system. The technique uses a Fourier‐transform analysis to directly measure the k ‐space trajectory produced by an arbitrary gradient waveform. In addition, the method can be easily extended to multiple dimensions and can be adapted to measuring residual gradient effects such as eddy currents. Several examples of gradient waveform and eddy‐current measurements are presented. Also, it is demonstrated how the eddy‐current measurements can be parameterized with an impulse‐response formalism for later use in system tuning. When compared to a peak‐fitting analysis, this technique provides a more direct extraction of the k ‐space measurements, which reduces the possibility of analysis error. This approach also has several advantages as compared to the conventional eddy‐current measurement technique, including the ability to measure very short time constant effects.