phase encoding


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phase en·cod·ing

in magnetic resonance imaging, the technique of inducing a gradient in the magnetic field in the x or y axis to induce phase differences with location.
Synonym(s): gradient encoding

phase encoding

An MRI term for the process of locating an MR signal by altering the phase of spins in one dimension with a pulsed magnetic field gradient along that dimension before acquiring the signal. Because each signal component experiences a different phase-encoding gradient pulse, its exact spatial reconstruction can be specifically and precisely located by the Fourier transformation analysis. Spatial resolution is directly correlated to the number of phase-encoding levels (gradients) used.
References in periodicals archive ?
Suppose [k.sub.y] and [k.sub.z] denote the k-space coefficients in the two phase encoding direction and N and M are the number of phase encoding steps in y and z direction, the pdf of VD is given by
Acronyms (F)(S)ISTA: (Fast) (subband adaptive) ISTA (I)CF: (Improved) cost function (I)DFT: (Inverse) discrete Fourier transform CS: Compressed sensing DWT: Discrete wavelet transform EPI: Echo planar imaging EPR: Energy preserving ratio ePRESS: Energy preserving sampling FE: Frequency encoding FOV: Field of view ISTA: Iterative shrinkage/thresholding algorithm ITA: Iterative thresholding algorithm MAE: Median absolute error MRI: Magnetic resonance imaging MS: Multislice MSE: Median square error PE: Phase encoding RAND: Random sampling ROS: Region of support SSFP: Steady state free precession TR: Repetition time VD: Variable density.
To simulate the undersampled k-space data, the sampling masks corresponding to reduction factors, R = 3 and 4, were generated using the function provided in the k-t FOCUSS toolbox, where the central 8 phase encoding lines were fully sampled.