(Gf) A frequency encoding gradient produces a magnetic gradient field present during MR signal acquisition to encode signals into different frequencies, depending on their position toward the gradient.
Also called readout gradient.

The difference between given signal frequency and a reference frequency.

A RF pulse containing energy only within a specified frequency range. Usually used for slice excitation or for selective saturation pulses.

The magnetic field outside the magnet, which is also called the stray field. Its strength depends on the magnet type and the field strength. The higher the field strength, the larger the fringe field.

See Magnetic Fringe Field.

(FWHM) A commonly used measure of the width at half the maximum value of peaked functions such as spectral lines or slice profiles and important measure of the quality of an imaging device and its spatial resolution. As the name states, the FWHM is measured by identifying the points on the signal curve, which are half the maximum value. The horizontal distance between these two points is called the FWHM. For a spectral line, this will be proportional to 1/T2.