Patent ID: 6049206
Filing Date: 2000-04-11
Classification: G01R

Abstract:
A method of performing magnetic resonance measurements in order to analyze a sample, comprising:providing at least one magnet generating a magnetic field B.sub.0 which is substantially static during the experiment and substantially spatially uniform over the sample, the magnetic field direction defining a z-reference axis along a longitudinal direction of the magnet;providing at least one radio frequency (RF) coil and applying an RF signal to the RF coil to generate an RF field B.sub.1, the RF coil and sample having characteristics such that the field generated is non-homogeneous over at least part of the sample;and compensating for the non-homogeneity of the RF field by applying an additional modulation to an initial RF pulse which can be expressed either as a phase modulation or as a frequency modulation,the phase modulation comprising a time-dependent phase function, .beta.(t) of an initial pulse B.sub.1.sup.init by the time-dependent phase function, .beta.(t) represented by:B.sub.1M =B.sub.1.sup.init exp (-i.beta.(t)).the frequency modulation function given by .OMEGA.(t)=d.beta.(t)/dt, wherein the form of frequency modulation function, .OMEGA.(t), is one that is substantially oscillating, that is reversing in sign periodically during the pulse;and wherein the oscillation is sufficiently rapid such that at least one complete cycle of frequency modulation occur during each pulse.