Patent ID: 7349729
Filing Date: 2008-03-25
Classification: A61B,G01R

Abstract:
1. A method of obtaining magnetic resonance signals with signal separation for at least two chemical species in a heterogeneous magnetic field using rapid gradient echo imaging, comprising the steps of: a) obtaining first magnetic resonance signals from pixels in an object having at least two chemical species using a first repetition time and a first echo time, b) obtaining at least second and third magnetic resonant signals from the pixels using second and third echo times, wherein the magnetic resonance signals at time, n=1 to N, for species, j =1 to M, having real, R, and imaginary, I, parts is given by:  and a least squares fitting of all signals is given by: where A is a known matrix for M species, c) determining a signal estimate for each species and for each pixel by combining all measured signals for the pixel using a linear least squares fitting directly on the signals from each pixel to decompose the chemical species, assuming a first value of field heterogeneity (ψ d) calculating a first error to the field heterogeneity, e) repeating step c) using the first value of field heterogeneity and the error from step d), f) repeating step d) to calculate a second error to the field heterogeneity, and g) updating the value of field heterogeneity and repeating steps c) and d) until an acceptable error is calculated, wherein:  where c