Nuclear magnetic resonance flow imaging

Claim 1

A method of acquiring an NMR signal providing motional information of a sample comprising the steps of: (a) applying an r.f. excitation signal to said sample for the subsequent production of an NMR signal; (b) applying spatial encoding gradient fields to said sample in a pulse sequence in which the gradient pulse train of a gradient in the direction in which motion is to be encoded exhibits a zero value first moment with respect to the timing of an r.f. excitation signal; (c) applying a motion encoding gradient field to said sample to encode motion in a given direction which is produced in response to a two-pulse gradient pulse sequence which exhibits a zero value zero moment and a non-zero value first moment; and (d) after the above steps, acquiring NMR signal information.

Claim 2

A method of acquiring an NMR signal providing motional information of a sample comprising the steps of: (a) applying an r.f. excitation signal to said sample for the subsequent production of an NMR signal; (b) applying spatial encoding gradient fields to said sample in a pulse sequence in which the gradient pulse train of a gradient in the direction in which motion is to be encoded exhibits a zero value first moment with respect to the timing of an r.f. excitation signal; (c) applying a motion encoding gradient field to said sample to encode motion in a given direction which is produced in response to a two-pulse gradient pulse sequence which exhibits a zero value zero moment and a non-zero value first moment; and (d) after the above steps, acquiring NMR signal information.

Claim 6

A method of measuring motion in a sample in an NMR imaging system comprising the steps of: (a) acquiring a first sequence of NMR data from said sample by applying r.f. pulses and spatial encoding gradient fields to said sample in the absence of an effective motion-encoding gradient, and reading the resulting NMR signals; (b) performing a Fourier transform on said first sequence of NMR data with respect to said spatial encoding gradient characteristics; (c) acquiring a second sequence of NMR data from said sample by applying r.f. pulses, spatial encoding gradient fields, and a motion-encoding gradient to said sample, and reading the resulting NMR signals; (d) performing a Fourier transform on said second sequence of NMR data with respect to said spatial encoding gradient characteristics; (e) forming a ratio image on a pixel-by-pixel basis by dividing pixels of said Fourier-transformed second sequence by respective pixels of said Fourier-transformed first sequence; wherein said ratio image is representative of motion in said sample.

Claim 7

A method of measuring motion in a sample in an NMR imaging system comprising the steps of: (a) acquiring a first sequence of NMR data from said sample by applying r.f. pulses and spatial encoding gradient fields to said sample in the absence of an effective motion-encoding gradient, and reading the resulting NMR signals; (b) performing a Fourier transform on said first sequence of NMR data with respect to said spatial encoding gradient characteristics; (c) acquiring a second sequence of NMR data from said sample by applying r.f. pulses, spatial encoding gradient fields, and a motion-encoding gradient to said sample, and reading the resulting NMR signals; (d) performing a Fourier transform on said second sequence of NMR data with respect to said spatial encoding gradient characteristics; (e) forming a ratio image on a pixel-by-pixel basis by dividing pixels of said Fourier-transformed second sequence by respective pixels of said Fourier-transformed first sequence; wherein said ratio image is representative of motion in said sample.

Claim 11

A method of measuring motion in a sample in an NMR imaging system comprising the steps of: (a) applying a sequence of excitation pulses, spatial-encoding gradients, and a first motion-encoding gradient to said sample, said first motion-encoding gradient being applied by means of a gradient pulse train which exhibits a first, non-zero value first moment; and acquiring NMR signals resulting from the application of said sequence of pulses and gradients; (b) applying at least one further sequence of excitation pulses, spatial-encoding gradients, and a second motion-encoding gradient to said sample, said second motion-encoding gradient being applied by means of a gradient pulse train which exhibits a second, non-zero value first moment, and acquiring NMR signals resulting from the application of said sequence of pulses and gradients; (c) performing a Fourier transform on said NMR signal information acquired in each of steps (a) and (b), respectively, with respect to said spatial encoding gradient characteristics; and (d) performing a Fourier transform on said acquired information with respect to the variation in the first moment of said motion-encoding gradient pulse train, whereby a plurality of images, each representing an amount of material in said sample with a different velocity value, are formed.

Claim 12

A method of measuring motion in a sample in an NMR imaging system comprising the steps of: (a) applying a sequence of excitation pulses, spatial-encoding gradients, and a first motion-encoding gradient to said sample, said first motion-encoding gradient being applied by means of a gradient pulse train which exhibits a first, non-zero value first moment; and acquiring NMR signals resulting from the application of said sequence of pulses and gradients; (b) applying at least one further sequence of excitation pulses, spatial-encoding gradients, and a second motion-encoding gradient to said sample, said second motion-encoding gradient being applied by means of a gradient pulse train which exhibits a second, non-zero value first moment, and acquiring NMR signals resulting from the application of said sequence of pulses and gradients; (c) performing a Fourier transform on said NMR signal information acquired in each of steps (a) and (b), respectively, with respect to said spatial encoding gradient characteristics; and (d) performing a Fourier transform on said acquired information with respect to the variation in the first moment of said motion-encoding gradient pulse train, whereby a plurality of images, each representing an amount of material in said sample with a different velocity value, are formed.

Claim 17

A method of acquiring an NMR signal providing motional information of a sample comprising the steps of: (a) applying an r.f. excitation signal to said sample for the subsequent production of an NMR signal; (b) applying spatial encoding gradient fields to said sample, one of said gradient fields being in the direction of a motion-encoding gradient and developed in response to a gradient pulse sequence exhibiting a zero value first moment; (c) applying motion-encoding gradients to said sample which are developed in response to a gradient pulse sequence exhibiting a zero value zero moment and a non-zero first moment; and (d) acquiring NMR signal information.

Claim 18

A method of acquiring an NMR signal providing motional information of a sample comprising the steps of: (a) applying an r.f. excitation signal to said sample for the subsequent production of an NMR signal; (b) applying spatial encoding gradient fields to said sample, one of said gradient fields being in the direction of a motion-encoding gradient and developed in response to a gradient pulse sequence exhibiting a zero value first moment; (c) applying motion-encoding gradients to said sample which are developed in response to a gradient pulse sequence exhibiting a zero value zero moment and a non-zero first moment; and (d) acquiring NMR signal information.