System and method for object-based initialization of magnetic field inhomogeneity in magnetic resonance imaging
First Claim
1. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising:
- a) directing the MRI system to acquire k-space data from an imaging volume at a plurality of different echo times;
b) reconstructing an image for each of the plurality of echo times using the k-space data acquired at the respective echo time;
c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the images reconstructed in step b);
d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c); and
wherein step c) includes combining the images reconstructed in step b) and estimating the distribution of magnetic susceptibility values from information in the combined image.
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Accused Products
Abstract
An object-based approach is used to initialize the magnetic field inhomogeneity estimation for chemical species separation, such as water-fat separation, and other imaging applications. For example, a susceptibility distribution in the subject being imaged is estimated from images reconstructed from single-echo or multi-echo k-space data and used to initialize the magnetic field inhomogeneity estimation. This approach can be applied to any complex-based chemical shift encoded chemical species separation technique and to other imaging applications, such as susceptibility-weighted imaging and quantitative susceptibility mapping. The field map can also be used to correct for image distortions and to generate magnetic field shimming values.
10 Citations
87 Claims
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1. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising:
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a) directing the MRI system to acquire k-space data from an imaging volume at a plurality of different echo times; b) reconstructing an image for each of the plurality of echo times using the k-space data acquired at the respective echo time; c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the images reconstructed in step b); d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c); and wherein step c) includes combining the images reconstructed in step b) and estimating the distribution of magnetic susceptibility values from information in the combined image. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising
a) directing the MRI system to acquire k-space data from an imaging volume at a plurality of different echo times; -
b) reconstructing an image for each of the plurality of echo times using the k-space data acquired at the respective echo time; c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the images reconstructed in step b); d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c); and performing a chemical species separation using the magnetic field inhomogeneity map estimated in step d). - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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35. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising:
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a) directing the MRI system to acquire k-space data from an imaging volume at a plurality of different echo times; b) reconstructing an image for each of the plurality of echo times using the k-space data acquired at the respective echo time; c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the images reconstructed in step b); d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c); and wherein step c) includes estimating transverse relaxation rates in the imaging volume from the images reconstructed in step b), associating the estimated transverse relaxation rates with iron concentrations in the image volume, and assigning magnetic susceptibility values to the magnetic susceptibility distribution based on the iron concentrations. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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52. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising:
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a) directing the MRI system to acquire k-space data from an imaging volume at a plurality of different echo times; b) reconstructing an image for each of the plurality of echo times using the k-space data acquired at the respective echo time; c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the images reconstructed in step b); d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c); and wherein step c) includes providing information about a metallic implant depicted in the images reconstructed in step b) and assigning magnetic susceptibility values to the magnetic susceptibility distribution based on the information about the metallic implant. - View Dependent Claims (53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
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69. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising:
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a) directing the MRI system to acquire k-space data from an imaging volume at a plurality of different echo times; b) reconstructing an image for each of the plurality of echo times using the k-space data acquired at the respective echo time; c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the images reconstructed in step b); d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c); and further comprising reducing distortions in the images reconstructed in step b) using the magnetic field inhomogeneity map estimated in step d). - View Dependent Claims (70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85)
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86. A method for estimating inhomogeneities in a magnetic field of a magnetic resonance imaging (MRI) system, the steps of the method comprising:
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a) directing the MRI system to acquire k-space data from an imaging volume; b) reconstructing an image from the acquired k-space data; c) estimating a distribution of magnetic susceptibility values in the imaging volume using information in the image reconstructed in step b); d) estimating a magnetic field inhomogeneity map from the distribution of magnetic susceptibility values estimated in step c); and wherein the k-space data acquired in step a) is single-echo k-space data. - View Dependent Claims (87)
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Specification