1. A method of detecting a nuclear magnetic resonance (NMR) signal from each of a plurality of spatial points in a sample along a first direction, the method comprising the steps of: A) locating the sample in a static magnetic field and applying a gradient magnetic field to the sample in the first direction; B) applying a first radio frequency (RF) pulse to the sample; C) detecting, after a predetermined duration of time t.sub.1 following application of the first RF pulse, an NMR signal from the sample; D) changing the magnitude of the gradient magnetic field at a rate which is sufficiently gradual that any eddy current induced in surrounding conductive materials as a result of the changing gradient magnetic field is small enough that any corresponding magnetic field generated by the eddy current is below a desired homogeneity of the static magnetic field; E) applying a second RF pulse to the sample; and F) detecting, after a duration equal to t.sub.1 following application of the second RF pulse, an NMR signal from the sample.