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  • Title: A method to measure arbitrary k-space trajectories for rapid MR imaging.
    Author: Mason GF, Harshbarger T, Hetherington HP, Zhang Y, Pohost GM, Twieg DB.
    Journal: Magn Reson Med; 1997 Sep; 38(3):492-6. PubMed ID: 9339451.
    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 fo 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.
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