Method for separating magnetic resonance imaging signals using spectral distinction of species

A method for producing an image of a subject with a magnetic resonance imaging (MRI) system in which signal contributions of at least two species are separated, the steps of the method comprising:

• a) acquiring, with the MRI system, multi-echo signal data from a subject;
• b) fitting the multi-echo signal data to a signal model in order to produce a plurality of signal separation solutions and a respective plurality of fitting residuals, the signal model including distinct terms for the at least two species;
• c) comparing the plurality of fitting residuals in order to identify a fitting residual corresponding to a correct signal separation solution;
• and
• d) reconstructing, from the acquired multi-echo signal data and using the correct signal separation solution, at least one of an image of the subject depicting substantially only one of the at least two species and an image of the subject depicting substantially only another one of the at least two species.

A method for producing an image of a subject with a magnetic resonance imaging (MRI) system in which signal contributions of at least two species are separated, the steps of the method comprising:

• a) acquiring, with the MRI system, multi-echo signal data from a subject;
• b) performing a signal separation using the acquired multi-echo signal data in order to produce signal contributions for each of the at least two species;
• c) producing, using the acquired multi-echo signal data, a spectral difference weighting map that depicts a probability of a correct signal separation solution at each pixel location therein, and that is indicative of spectral differences between a selected pair of the at least two species;
• d) producing, using the acquired multi-echo signal data, a smoothness weighting map that depicts a probability of an off-resonance error at pixel locations therein, and that is indicative of a local gradient of a field map estimate;
• e) updating the signal contributions using the spectral difference weighting map and the smoothness weighting map;
• and
• f) reconstructing at least one of an image depicting substantially only the one of the at least two species using the acquired multi-echo signal data and an associated one of the updated signal contributions, and an image depicting substantially only another one of the at least two species using the acquired multi-echo signal data and an associated another one of the updated signal contributions.