Claim 1:

In a gyromagnetic resonance instrument which performs a measurement cycle in which a FID signal produced by gyromagnetic material having a transverse magnetic moment is detected and processed to produce an indication of the amount of transverse magnetization, the improvement comprising:

• an oscillator for producing an excitation signal at the Larmor frequency of the gyromagnetic material;

• an excitation field gradient coil coupled to the oscillator and mounted in the instrument to produce a transversely directed magnetic field at the Larmor frequency which has a magnitude gradient in a preset direction; and

• control means for producing a motion sensitized FID signal by controlling the excitation signal applied to the excitation field gradient coils such that a bi-phasic excitation field gradient is applied to the gyromagnetic material.