US 7,924,003 B2 · Method for water-fat separation and T2* estimation in an MRI system employing multiple fat spectral peaks and fat spectrum self-calibration

Abstract

NMR signal contributions from water and fat are separated using a model of the fat resonant frequency spectrum that has multiple resonant peaks. The relative frequencies of the multiple fat spectrum peaks are known a priori and their relative amplitudes are determined using a self-calibration process. With the determined relative amplitudes of the fat spectrum peaks, acquired NMR signals are modeled. Using this model and NMR signal data acquired at a plurality of echo times (TE), the signal contribution from multiple fat spectrum peaks is separated from the acquired NMR signal data. A combined image is alternatively produced from weighted contributions of the separated water and fat images. Additionally, a more accurate estimation of the apparent relaxation time and rate (T*2 and R*2, respectively) is alternatively performed.

Claims27

Dependent claims

A method for producing an image of a subject with a magnetic resonance imaging (MRI) system, the image having a suppressed signal from a selected species, the steps comprising:

a) acquiring, with the MRI system and at a plurality of different echo times, NMR image signals from a subject containing the selected species, wherein the selected species has a resonant frequency spectrum with multiple peaks, each of the multiple peaks having a different known resonant frequency;
b) reconstructing images of the subject from the acquired NMR image signals;
c) determining, from the images of the subject reconstructed in step b), a relative peak amplitude of at least two of the multiple peaks of the selected species;
and
d) producing, using the images of the subject reconstructed in step b) and the at least two relative peak amplitudes of the selected species determined in step d), an image depicting the subject having a suppressed signal from the selected species.

2 more elements

A method for producing an image of a subject with a magnetic resonance imaging (MRI) system, the steps comprising:

a) performing, with the MRI system, a pulse sequence having a first echo time;
b) acquiring NMR image signals, produced by the performance of the pulse sequence in step a), from the subject, the subject containing a selected species having a resonant frequency spectrum with multiple peaks, each of the multiple peaks having a different known resonant frequency;
c) repeating steps a) and b) with a pulse sequence having a different echo time during each repetition;
d) determining, from the NMR image signals acquired in steps b) and c), a relative peak amplitude of at least two of the multiple peaks of the selected species;
e) producing, using the NMR image signals acquired in steps b) and c) and the relative peak amplitudes of at least two of the multiple peaks of the selected species determined in step d):
a separated image depicting the subject, the separated image having suppressed signal from the selected species;
and
a selected species image depicting the subject, the selected species image having substantially only signal from the selected species;
and
f) producing a combined image depicting the subject by combining, with corresponding selected weightings, the separated image depicting the subject and selected species image depicting the subject produced in step e).

7 more elements

Dependencies are inferred from the claim text.

Method for water-fat separation and T2* estimation in an MRI system employing multiple fat spectral peaks and fat spectrum self-calibration

Life of this patent

Method for water-fat separation and T2* estimation in an MRI system employing multiple fat spectral peaks and fat spectrum self-calibration

Life of this patent

Abstract

Claims27