In physics, the magnitude (length) of a vector is a scalar in the physical sense, i.e. a physical quantity independent of the coordinate system, expressed as the product of a numerical value and a physical unit, not just a number.

See also Longitudinal Magnetization and Net Magnetization Vector.

The normal image display, at which the grey scale of a display element corresponds to the magnitude of the MR signal.

Magnitude calculation e.g. cuts the amplitude information, or can be used to obtain pure absorption Lorentzian lineshapes in spectroscopy.

A type of MRA used to display slow flow across a large volume with a good resolution. Two data volumes are measured; the flow-rephased images show bright signal, the flow-dephased image show dark flow, whereby in both data volumes the signal of the stationary tissue looks the same. The data volumes are subtracted and the signal intensity of flowing blood remains.

A microscopic group of spins, which resonate at the same frequency. The spin precesses around a circle in the xy-plane and the net magnetization is the length, amplitude or magnitude of the magnetization vector Mxy: the quantity normally represented on a pixel-by-pixel basis in a MR image (thus amplitude or magnitude image).