Mri method for high liver iron measurement using magnetic susceptibility

Abstract

A subject (22), such as a human patient, is positioned with a region of interest (24), such as the liver, close proximity to a phantom (12). A Volume image through the liver, the phantom, and adjacent portions of the subject are collected (40) with a magnetic resonance scanner. The phase component of the magnetic resonance data is reconstructed (50) into a three-dimensional phase map. An actually measured field map H.sub.m (r) is determined (42) from the phase map. A geometric model of the volumes occupied by the liver, the phantom, and adjacent portions of the subject are defined mathematically (44). A calculation routine (46) calculates a calculated or estimated field map H.sub.c (r) of the distortions to the magnetic field in the phantom which would be caused by the model. A least squares fit routine (48) (i) compares the calculated field map and the measured field map, (ii) based on the difference adjusts a susceptibility of material in the region of interest as defined in the model, and (iii) recalculates the field map. This fitting procedure is iteratively repeated until a susceptibility is determined for the region of interest which predicts the actually measured field map. This susceptibility is proportional to iron concentration.