Method for simultaneously obtaining three-dimensional NMR angiograms and stationary tissue NMR images
First Claim
1. A method for simultaneously obtaining a three dimensional (3D) nulcear magnetic resonance (NMR) image of moving spins in a region of a sample, and a 3D NMR image of stationary spins in the same sample region, comprising the steps of:
- (a) immersing the sample in a main static magnetic field;
(b) nutating, in an excitation subsequence of each of a plurality S of successive NEX=1 NMR sequences, the spins of all nuclei of a selected species;
(c) generating, in a flow-encoding subsequence after each nutation, at least one modulated flow-encoding signal pulse in a first magnetic field gradient impressed upon the sample in a first direction selected to cause a resulting NMR response echo signal from the spin of a nucleus moving in the first direction to be different from the NMR response echo signal from the spin of a substantially stationary nucleus;
(d) then, in a subsequent imaging subsequence, acquiring responsive to a readout magnetic field gradient impressed upon the sample in a second direction, independent of the first direction, a set of data from the NMR response signal evoked, from at least the sample portion, with each of the plurality S of combinations of phase-encoding amplitudes operating upon the selected sample portion in the remaining two independent directions of a 3D Cartesian coordinate system;
(e) processing the data in each of the acquired NMR response signal data sets to generate at least one of(1) a difference data set from which response data obtained from stationary nuclei has been substantially removed,(2) a summation data set from which response data obtained from moving nuclei has been substantially removed, and(3) a phase data set indicating direction of flow for flow amplitudes obtained in the difference data set; and
(f) generating, responsive to the plurality of data sets, both an image of moving spins, projected in a selected plane in a 3D volume, and an image of stationary spins in the same plane.
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Abstract
A method for simultaneously obtaining a three-dimensional nuclear magnetic resonance (NMR) angiographic image of moving spins associated with fluid flow in a region of a living organism sample, and a three-dimensional NMR image of stationary tissue in the same sample region, by immersing the sample in a main static magnetic field; nutating, in an excitation subsequence of each of a plurality of NMR sequences, the nuclear spins and the generating a flow-encoding magnetic field gradient selected to cause a resulting NMR response echo signal from the spin of a moving nucleus to be different from the NMR response echo signal from the spin of a substantially stationary nucleus. The acquired response data is processed to provide at least one of (1) a difference data set from which response data obtained from stationary nuclei has been substantially removed, (2) a summation data set from which response data obtained from moving nuclei has been substantially removed, and (3) a set of phase data indicating direction of flow for flow amplitudes obtained in set (1), in order to generate both an angiographic image lying in a selected plane in a three-dimensional volume, and an image of stationary tissue in the same plane.
25 Citations
16 Claims
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1. A method for simultaneously obtaining a three dimensional (3D) nulcear magnetic resonance (NMR) image of moving spins in a region of a sample, and a 3D NMR image of stationary spins in the same sample region, comprising the steps of:
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(a) immersing the sample in a main static magnetic field; (b) nutating, in an excitation subsequence of each of a plurality S of successive NEX=1 NMR sequences, the spins of all nuclei of a selected species; (c) generating, in a flow-encoding subsequence after each nutation, at least one modulated flow-encoding signal pulse in a first magnetic field gradient impressed upon the sample in a first direction selected to cause a resulting NMR response echo signal from the spin of a nucleus moving in the first direction to be different from the NMR response echo signal from the spin of a substantially stationary nucleus; (d) then, in a subsequent imaging subsequence, acquiring responsive to a readout magnetic field gradient impressed upon the sample in a second direction, independent of the first direction, a set of data from the NMR response signal evoked, from at least the sample portion, with each of the plurality S of combinations of phase-encoding amplitudes operating upon the selected sample portion in the remaining two independent directions of a 3D Cartesian coordinate system; (e) processing the data in each of the acquired NMR response signal data sets to generate at least one of (1) a difference data set from which response data obtained from stationary nuclei has been substantially removed, (2) a summation data set from which response data obtained from moving nuclei has been substantially removed, and (3) a phase data set indicating direction of flow for flow amplitudes obtained in the difference data set; and (f) generating, responsive to the plurality of data sets, both an image of moving spins, projected in a selected plane in a 3D volume, and an image of stationary spins in the same plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for simultaneously obtaining a three dimensional (3D) nuclear magnetic resonance (NMR) image of moving spins in a region of a sample, and a 3D NMR image of stationary spins in the same sample region, comprising the steps of:
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(a) immersing the sample in a main static magnetic field; (b) nutating, in an excitation subsequence of each of a plurality S of successive NEX=2 pairs of NMR sequences, the spins of all nuclei of a selected species; (c) generating, in a flow-encoding subsequence after each nutation, at least one modulated flow-encoding signal pulse in a first magnetic field gradient impressed upon the sample, in a first direction selected to cause a resulting NMR response echo signal from the spin of a nucleus moving in the first direction to be different from the NMR response echo signal from the spin of a substantially stationary nucleus, and modulating the flow-encoding pulses in alternating ones of the sequences to have each of the flow-encoding pulses of a polarity opposite to the polarity of the like-positioned flow-encoding pulse in the previous sequence; (d) theh, in a subsequent imaging subsequence, acquiring responsive to a readout magnetic field gradient imposed upon the sample in a second direction, independent of the first direction, a set of data from the NMR response signal evoked, from at least the sample portion, with each of the plurality S of combinations of phase-encoding amplitudes operating upon the selected sample portion in the remaining two independent directions of a 3D Cartesian coordinate system, in each successive pair of sequences; (e) processing the data in each successive pair of the acquired NMR response signal data sets to generate at least one of (1) a difference data set from which response data obtained from stationary nuclei has been substantially removed, (2) a summation data set from which response data obtained from moving nuclei has been substantially removed, and (3) a phase data set indicating direction of flow for flow amplitudes obtained in the difference data set; and (f) generating, responsive to the plurality of data sets, both an image of moving spins, projected in a selected plane in a 3D volume, and an image of stationary spins in the same plane. - View Dependent Claims (12, 13, 14, 15, 16)
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Specification