Method and system for measuring the diffusion tensor and for diffusion tensor imaging
First Claim
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1. A magnetic resonance spectroscopy system comprising:
- means for applying a static magnetic field to an object under examination;
means for applying gradient magnetic fields to the object;
means for applying a high frequency pulse to the object;
detecting means for detecting a magnetic resonance signal from the object;
control means for causing said means for applying gradient magnetic fields, and means for applying a high frequency pulse to operate in a predetermined sequence so as to induce magnetic resonance within the object, wherein said control means includes means for generating a plurality of echo signals corresponding to non-collinearly dependent directions of said gradient magnetic fields; and
means for processing data based on the magnetic resonance signal detected by said detecting means to obtain magnetic resonance information, wherein said means for processing data provides a signal that is a function of the components of a diffusion tensor representing translational displacement of spin labeled species for said object on the basis of said plurality of echo signals according to a predetermined relationship between said echoes and said components.
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Abstract
A method and system for measuring the effective diffusion tensor for spin labeled particles, and generating images therefrom. The effective diffusion tensor is related to the echo intensity in an NMR spin-echo experiment. This relationship is used to design experiments from which the diffusion tensor components are estimated. Estimation of Deff provides the theoretical basis for a new MRI modality, diffusion tensor imaging. Diffusion ellipsoids may be used for generating images representative of physical characteristics of the observed object. Scalar invariants of the diffusion tensor are also used for imaging.
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Citations
35 Claims
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1. A magnetic resonance spectroscopy system comprising:
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means for applying a static magnetic field to an object under examination; means for applying gradient magnetic fields to the object; means for applying a high frequency pulse to the object; detecting means for detecting a magnetic resonance signal from the object; control means for causing said means for applying gradient magnetic fields, and means for applying a high frequency pulse to operate in a predetermined sequence so as to induce magnetic resonance within the object, wherein said control means includes means for generating a plurality of echo signals corresponding to non-collinearly dependent directions of said gradient magnetic fields; and means for processing data based on the magnetic resonance signal detected by said detecting means to obtain magnetic resonance information, wherein said means for processing data provides a signal that is a function of the components of a diffusion tensor representing translational displacement of spin labeled species for said object on the basis of said plurality of echo signals according to a predetermined relationship between said echoes and said components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for estimating at least one component of a diffusion tensor representing translational displacement of spin labeled species for a sample inserted in an NMR apparatus comprising the steps of:
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deriving a relationship between an NMR signal and said diffusion tensor; generating a pulse sequence in said NMR apparatus for generating said NMR signal; calculating said at least one component of said diffusion tensor based on said NMR signal, according to said relationship. - View Dependent Claims (13, 14, 15)
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16. A method for estimating at least one component of a diffusion tensor representing translational displacement of spin labeled species for a localized region of a sample comprising the steps of:
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immersing the sample in a static magnetic field; exciting nuclear magnetic resonance echoes in said sample by application of a predetermined pulse sequence; calculating said at least one component of said diffusion tensor based on said echoes, according to a predetermined relationship between said echoes and said components. - View Dependent Claims (17)
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18. A method for estimating at least one component of a diffusion tensor representing translational displacement of spin labeled species for a sample inserted in a resonance apparatus, said resonance apparatus having means for inducing a signal in said sample, including means for generating gradient magnetic fields in non-linearly dependent directions, means for applying a static magnetic field, means for generating high frequency pulses, and means for receiving said signal, comprising the steps of:
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deriving a relationship between said signal and said diffusion tensor; generating a pulse sequence in said resonance apparatus for generating said signal; calculating said at least one component of said diffusion tensor based on said signal, according to said relationship. - View Dependent Claims (19)
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20. A NMR apparatus comprising:
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means for generating an echo signal in said sample; and means for processing said echo signal into a signal that is a function of a diffusion tensor representing translational displacement of spin labeled species for said sample. - View Dependent Claims (21, 22, 23, 24)
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25. A method for measuring NMR of a sample inserted into a NMR apparatus, comprising the steps of:
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generating an echo signal in said sample; and processing said echo signal into a signal that is a function of a diffusion tensor representing translational displacement of spin labeled species for said sample. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32)
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33. A method for measuring NMR of a sample inserted into a NMR apparatus, said method comprising the steps of:
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generating an echo signal in said sample, said echo signal encoded according to the diffusion tensor of said spatially translating component; and processing said echo signal into a signal representative of a diffusion tensor representing translational displacement of spin labeled species for said sample. - View Dependent Claims (34, 35)
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Specification