Patent Document ID: 5551431
Application ID: 08318057
Patent Flag: 1

Claim One:
1. A method for correcting for intensity inhomogeneities in a radiofrequency gain field of magnetic resonance imaging equipment for imaging human tissue having intensity inhomogeneities in its radiofrequency sensitivity, comprising the steps of modeling image intensities that are due to components of said human tissue; modeling image inhomogeneities that are not due to said human tissue; combining said models into a nonlinear estimator of intensity inhomogeneities; constructing an iterative algorithm for obtaining estimates from said nonlinear estimator that alternates between the following steps: (a) estimating the probabilities of various components of said human tissue throughout an image based on the results of step (b) for each iteration except the first; (b) estimating said intensity inhomogeneities by predicting intensities based on the results of step (a) for each iteration except the first and comparing these estimates to intensities that were observed, and filtering intensity differences; acquiring intensity data by exciting nuclear magnetic resonance in said human tissue with a magnetic field induced by a transmitting coil of said magnetic resonance imaging equipment and then detecting currents induced in a receiving coil of said magnetic resonance imaging equipment, wherein said acquired intensity data has been disturbed by said gain field inhomogeneities; obtaining estimates of said intensity inhomogeneities from said nonlinear estimator using said acquired intensity data in conjunction with said iterative algorithm; and displaying an image of said human tissue which has been corrected to compensate for said estimated intensity inhomogeneities.