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A Method to measure arbitrary k ‐space trajectories for rapid MR imaging
Author(s) -
Mason Graeme F.,
Harshbarger Todd,
Hetherington Hoby P.,
Zhang Yantian,
Pohost Gerald M.,
Twieg Donald B.
Publication year - 1997
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.1910380318
Subject(s) - physics , k space , measure (data warehouse) , waveform , eddy current , trajectory , nuclear magnetic resonance , shielded cable , spiral (railway) , pulse (music) , gradient descent , sampling (signal processing) , mathematical analysis , optics , computer science , mathematics , artificial intelligence , detector , telecommunications , quantum mechanics , database , fourier transform , voltage , astronomy , artificial neural network
Abstract A method to measure arbitrary k ‐space trajectories was developed to compensate for nonideal gradient performance during rapid magnetic resonance (MR) imaging with actively or nonactively shielded gradients at a magnetic field strength of 4.1 T. Accurate MR image reconstruction requires knowledge of the k‐trajectory produced by the gradient waveforms during k ‐space sampling. Even with shielded gradients, residual eddy currents and imperfections in gradient amplifier performance can cause the true k ‐space trajectory to deviate from the ideal trajectory. The k ‐space determination was used for spiral gradient‐echo imaging of the human brain. While individual calibrations are needed for new pulse sequences, the method of k ‐space determination can be used for any sequence of preparation pulses and readout gradient waveforms and should prove useful for other trajectories, including the rastered lines of echo‐planar imaging.