Patent ID: 6246238
Filing Date: 2001-06-12
Classification: G01R

Abstract:
An NMR method for measuring NMR signals from a sample of magnetic spins, the method comprising the steps of:a) locating the spins in an external magnetic field, wherein the spins have a distribution of Larmor frequencies in dependence on at least one of a type of nuclei, inhomogeneities in said external magnetic field, and an applied magnetic field gradient;b) irradiating a first radio frequency pulse sequence to effect periodic modulation of z-magnetization of the spins at a modulation separation 2.DELTA..omega. relative to said distribution of Larmor frequencies;c) waiting a time separation tm;d) irradiating a second radio frequency pulse sequence to transfer said periodic modulation of z-magnetization into transverse magnetization of the spins, wherein at least one of said first and said second radio frequency pulse sequence has a periodic rectangular excitation shape of said modulation separation 2.DELTA..omega.;e) waiting a time in dependence on said modulation separation 2.DELTA..omega. for coherence of said transverse magnetization; andf) measuring the NMR signal.