Patent Document ID: 8488859
Application ID: 12910909
Patent Status: 1

Claim One:
1. A method for determining a concentration of fat within a region of a subject, comprising: acquiring at least three gradient echo images e 1 , e 2 , and e 3 of a region of a subject from at least two different flip angles α 1 and α 2 within a repetition time TR for a total of at least six gradient echo images e 1 α 1 , e 2 α 1 , e 3 α 1 , e 1 α 2 , e 2 α 2 , and e 3 α 2 , wherein gradient echo images e 1 α 1 , e 1 α 2 , e 3 α 1 , and e 3 α 2 occur at an in-phase time when resonance signals of fat and water are in-phase with one another and gradient echo images e 2 α 1 , and e 2 α 2 occur at an opposed-phase time when the resonance signals of fat and water are 180° out of phase with one another; approximating a T2* relaxation time map from the in-phase gradient echo images based on the α 1 flip angle or the α 2 flip angle; approximating a T1 relaxation time map from the in-phase gradient echo images based on the α 1 flip angle and the α 2 flip angle; distinguishing between fat and water signals within the gradient echo images based on observed relative signal phase; modulating the amplitude of the fat and water signal images using the T2* relaxation time and T1 relaxation time maps; determining a ratio between fat and water signals for one or more voxels of the gradient echo images based on the amplitude modulated fat and water signal images; and displaying the determined ratio between fat and water for a desired voxel of the gradient echo images, wherein the T2* relaxation time map is approximated from the in-phase gradient echo images according to the following equations: T ⁢ ⁢ 2 α ⁢ ⁢ 1 * = ( TE ⁢ ⁢ 3 - TE ⁢ ⁢ 1 ) ln ⁡ ( S e ⁢ ⁢ 1 , α ⁢ ⁢ 1 / S e ⁢ ⁢ 3 , α ⁢ ⁢ 1 ) ⁢ ⁢ and ⁢ ⁢ T ⁢ ⁢ 2 α ⁢ ⁢ 2 * = ( TE ⁢ ⁢ 3 - TE ⁢ ⁢ 1 ) ln ⁡ ( S e ⁢ ⁢ 1 , α ⁢ ⁢ 2 / S e ⁢ ⁢ 3 , α ⁢ ⁢ 2 ) where TE 1 is a time of the acquisition of the e 1 images, TE 3 is a time of the acquisition of the e 3 images, S e1,α1 is a signal of the e 1 α 1 gradient echo image, S e3,α1 is a signal of the e 3 α 1 gradient echo image, S e1,α2 is a signal of the e 1 α 2 gradient echo image, and S e3,α2 is a signal of the e 3 α 2 gradient echo image.