Abstract: An apparatus and method for separating the NMR signal contributions from a plurality of different species having different chemical shifts is disclosed. The apparatus acquires MR image data sets including a first species signal and a second species signal, generates a first species image from the acquired MR image data, and generates a second species image from the acquired MR image data. The apparatus also identifies voxels in the second species image representative of only the second species and, for voxels identified as being representative of only the second species, calculates a fraction of the second species signal appearing in the first species image. The apparatus generates a modified first species image based on the fraction of the second species signal appearing in the first species image, with the modified first species image having a different fraction of the second species as compared to the first species image.

Abstract: Methods are disclosed for calculating a fat fraction corrected for noise bias of one or more voxels of interest using a magnetic resonance imaging (MRI) system. A plurality of image data sets are obtained each corresponding to NMR k-space data acquired using a pulse sequence with an individual associated echo time tn. A system of linear equations is formed relating image signal values to a desired decomposed calculated data vector having a component such as a water and fat combination having zero mean noise, or having a real fat component and a real water component. A fat fraction is calculated from at least one component of the decomposed calculated data vector. In another embodiment, the system of linear equations is normalized and can directly estimate a fat fraction or a water fraction having reduced noise bias.

Abstract: A method for producing an image of a subject with a magnetic resonance imaging (MRI) system in which a signal contribution of a chemical species is depicted and a signal contribution of another chemical species is substantially separated is provided. For example, the provided method is applicable for water-fat separation. Spectral differences between at least two different chemical species are exploited to produce a weighting map that depicts the likelihood that one chemical species being depicted as another. A weighting map that characterizes the smoothness of a field map variation is also produced. These weighting maps are utilized to produce a correct field map estimate, such that a robust separation of the signal contributions of the at least two chemical species can be performed.

Abstract: An apparatus and method for separating the NMR signal contributions from a plurality of different species having different chemical shifts is disclosed. The apparatus acquires MR image data sets including a first species signal and a second species signal, generates a first species image from the acquired MR image data, and generates a second species image from the acquired MR image data. The apparatus also identifies voxels in the second species image representative of only the second species and, for voxels identified as being representative of only the second species, calculates a fraction of the second species signal appearing in the first species image. The apparatus generates a modified first species image based on the fraction of the second species signal appearing in the first species image, with the modified first species image having a different fraction of the second species as compared to the first species image.

Abstract: Methods are disclosed for calculating a fat fraction corrected for noise bias of one or more voxels of interest using a magnetic resonance imaging (MRI) system. A plurality of image data sets are obtained each corresponding to NMR k-space data acquired using a pulse sequence with an individual associated echo time tn. A system of linear equations is formed relating image signal values to a desired decomposed calculated data vector having a component such as a water and fat combination having zero mean noise, or having a real fat component and a real water component. A fat fraction is calculated from at least one component of the decomposed calculated data vector. In another embodiment, the system of linear equations is normalized and can directly estimate a fat fraction or a water fraction having reduced noise bias.

Abstract: A method for producing an image of a subject with a magnetic resonance imaging (MRI) system in which a signal contribution of a chemical species is depicted and a signal contribution of another chemical species is substantially separated is provided. For example, the provided method is applicable for water-fat separation. Spectral differences between at least two different chemical species are exploited to produce a weighting map that depicts the likelihood that one chemical species being depicted as another. A weighting map that characterizes the smoothness of a field map variation is also produced. These weighting maps are utilized to produce a correct field map estimate, such that a robust separation of the signal contributions of the at least two chemical species can be performed.

Abstract: Methods and systems are provided for processing a magnetic resonance images. In one embodiment, first and second sets of lines of magnetic resonance imaging signals are acquired. The acquired sets of lines have readout gradients that are reversed in polarity with respect to one another. A two-dimensional phase error is determined using the first and second set of lines.

Abstract: Methods are disclosed for calculating a fat fraction corrected for noise bias of one or more voxels of interest using a magnetic resonance imaging (MRI) system. A plurality of image data sets are obtained each corresponding to NMR k-space data acquired using a pulse sequence with an individual associated echo time tn. A system of linear equations is formed relating image signal values to a desired decomposed calculated data vector having a component such as a water and fat combination having zero mean noise, or having a real fat component and a real water component. A fat fraction is calculated from at least one component of the decomposed calculated data vector. In another embodiment, the system of linear equations is normalized and can directly estimate a fat fraction or a water fraction having reduced noise bias.

Abstract: A system and method for quantitative species signal separation in MR imaging is disclosed. An MR imaging apparatus includes an MRI system and a computer programmed to cause the MRI system to apply a pulse sequence and acquire multi-echo source data for the pulse sequence that includes a phase component and a magnitude component. The computer is further programmed to determine a first estimate of a first species content and a first estimate of a second species content based on the multi-echo source data, and determine a second estimate of the first species content and a second estimate of the second species content based on the multi-echo source data.

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.

Abstract: Methods and systems are provided for processing a magnetic resonance images. In one embodiment, first and second sets of lines of magnetic resonance imaging signals are acquired. The acquired sets of lines have readout gradients that are reversed in polarity with respect to one another. A two-dimensional phase error is determined using the first and second set of lines.

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 (T2* and R2*, respectively) is alternatively performed.

Abstract: A method of separating signals from at least two species in a body using echo-coherent time magnetic resonance imaging is provided. A plurality of echo signals is acquired at acquisition times optimized based on the noise properties of images with different variance with possibly correlated noise resulting in possibly asymmetrically positioned images with respect to an echo time. The plurality of echo signals is combined iteratively by using a maximum likelihood decomposition algorithm for non-identically distributed noise.

Abstract: Methods are disclosed for calculating a fat fraction corrected for noise bias of one or more voxels of interest using a magnetic resonance imaging (MRI) system. A plurality of image data sets are obtained each corresponding to NMR k-space data acquired using a pulse sequence with an individual associated echo time tn. A system of linear equations is formed relating image signal values to a desired decomposed calculated data vector having a component such as a water and fat combination having zero mean noise, or having a real fat component and a real water component. A fat fraction is calculated from at least one component of the decomposed calculated data vector. In another embodiment, the system of linear equations is normalized and can directly estimate a fat fraction or a water fraction having reduced noise bias.

Abstract: A method for generating a magnetic resonance images is provided. A magnetic resonance imaging excitation is applied. A plurality of magnetic resonance image signals is acquired. The plurality of image signals is combined iteratively by using a regularized decomposition algorithm. An image created from combining the plurality of image signals iteratively is displayed.

Abstract: A method for generating dynamic magnetic resonance images is provided. A cyclical magnetic resonance imaging excitation is applied for a plurality of cycles at a cycle rate. A plurality of magnetic resonance image echoes is acquired for each cycle. A plurality of frames of images is generated from the acquired plurality of magnetic resonance echoes at a frame rate that is at least twice the cycle rate, wherein each frame of the plurality of frames is generated from a plurality of echoes and wherein some of the plurality of frames are generated from magnetic resonance image echoes of adjacent cycles.

Abstract: A method for generating a self-calibrating parallel multiecho magnetic resonance image is provided. A magnetic resonance imaging excitation is applied. A first echo at a first echo time in a first pattern is acquired. A second echo at a second echo time different from the first echo phase in a second pattern different from the first pattern is acquired. The acquired first echo and acquired second echo are used to generate an image in an image pattern, wherein none of the acquired echoes for generating the image have the same pattern as the image pattern.

Abstract: A method for generating a magnetic resonance image is provided. A magnetic resonance imaging excitation is applied for a plurality of cycles at a cycle rate. A plurality of magnetic resonance image echoes is acquired for each cycle. A decay map is estimated from the plurality of magnetic resonance image echoes for each cycle. The estimated decay map is used to generate an image for at least two different species.

Abstract: A method for generating dynamic magnetic resonance images is provided. A cyclical magnetic resonance imaging excitation is applied for a plurality of cycles at a cycle rate. A plurality of magnetic resonance image echoes is acquired for each cycle. A plurality of frames of images is generated from the acquired plurality of magnetic resonance echoes at a frame rate that is at least twice the cycle rate, wherein each frame of the plurality of frames is generated from a plurality of echoes and wherein some of the plurality of frames are generated from magnetic resonance image echoes of adjacent cycles.

Abstract: A method for generating a self-calibrating parallel multiecho magnetic resonance image is provided. A magnetic resonance imaging excitation is applied. A first echo at a first echo time in a first pattern is acquired. A second echo at a second echo time different from the first echo phase in a second pattern different from the first pattern is acquired. The acquired first echo and acquired second echo are used to generate an image in an image pattern, wherein none of the acquired echoes for generating the image have the same pattern as the image pattern.