Patent ID: 6690167
Filing Date: 2004-02-10
Classification: G01R,G01V

Abstract:
A method of making nuclear magnetic resonance measurement of a medium, comprising:(a) magnetically polarizing nuclei in said medium with a static magnetic field; (b) defining least one sensitive volume of the medium said at least one sensitive volume having an associated frequency of a radio frequency (RF) signal; (c) defining at least one modified CPMG pulse sequence associated with the at least one sensitive volume, said at least one modified CPMG pulse sequence comprising a wait time, an excitation pulse, at least one refocusing pulse, and a time interval between the excitation pulse and the at least one refocusing pulse, wherein the at least one refocusing pulse has a tipping angle less than 180Â°; (d) acquiring NMR pulse echo data using the at least one defined pulse sequence; and (e) processing the acquired NMR pulse echo data to obtain an estimated value of a parameter of interest of the medium, said estimated value having a relative difference of less than 10% compared to an estimated value of the parameter obtained using a standard CPMG pulse sequence with a tipping angle of the refocusing pulse substantially equal to 180Â°, said difference being less than 10% over a range of values of between 1 and 100 of a ratio of a longitudinal and transverse relaxation time of said medium.