Spiral three-dimensional fourier transform NMR scan

Claim 1

A method for acquiring an NMR data set which is employed to reconstruct an image using a Fourier transformation, the steps comprising: performing an NMR pulse sequence in an NMR system to acquire sample NMR data for the NMR data set, the NMR pulse sequence including a first phase encoding gradient pulse having a magnitude which determines the location of the sample NMR data along a first axis in a two-dimensional k-space, and a second phase encoding gradient pulse having a magnitude which determines the location of the sample NMR data along a second axis in the two-dimensional k-space; repeating the NMR pulse sequence to acquire sample NMR data for the NMR data set from locations in a region surrounding the origin of said two-dimensional k-space, the magnitudes of said first and second phase encoding gradient pulses being stepped through values such that the location of successive samples forms a spiral trajectory in the two-dimensional k-space.

Claim 2

A method for acquiring an NMR data set which is employed to reconstruct an image using a Fourier transformation, the steps comprising: performing an NMR pulse sequence in an NMR system to acquire sample NMR data for the NMR data set, the NMR pulse sequence including a first phase encoding gradient pulse having a magnitude which determines the location of the sample NMR data along a first axis in a two-dimensional k-space, and a second phase encoding gradient pulse having a magnitude which determines the location of the sample NMR data along a second axis in the two-dimensional k-space; repeating the NMR pulse sequence to acquire sample NMR data for the NMR data set from locations in a region surrounding the origin of said two-dimensional k-space, the magnitudes of said first and second phase encoding gradient pulses being stepped through values such that the location of successive samples forms a spiral trajectory in the two-dimensional k-space.

Claim 5

A method for acquiring a three-dimensional NMR data set for reconstructing an image using a Fourier transformation, which comprises: performing a scan comprised of a series of NMR pulse sequences, each NMR pulse sequence including: producing a first phase encoding gradient pulse having a gradient directed along one of the three dimensions, and having a magnitude which is stepped through a series of values during the scan; producing a second phase encoding gradient pulse having a gradient directed along a second of said three dimensions, and having a magnitude which is stepped through a series of values during the scan; producing a read-out gradient pulse having a gradient directed along the third of said three dimensions; and acquiring an NMR signal for the NMR data set during the production of the read-out gradient; wherein the series of values through which the magnitudes of the first and second phase encoding pulses are stepped during the scan map out a spiral trajectory in a two-dimensional k-space.

Claim 6

A method for acquiring a three-dimensional NMR data set for reconstructing an image using a Fourier transformation, which comprises: performing a scan comprised of a series of NMR pulse sequences, each NMR pulse sequence including: producing a first phase encoding gradient pulse having a gradient directed along one of the three dimensions, and having a magnitude which is stepped through a series of values during the scan; producing a second phase encoding gradient pulse having a gradient directed along a second of said three dimensions, and having a magnitude which is stepped through a series of values during the scan; producing a read-out gradient pulse having a gradient directed along the third of said three dimensions; and acquiring an NMR signal for the NMR data set during the production of the read-out gradient; wherein the series of values through which the magnitudes of the first and second phase encoding pulses are stepped during the scan map out a spiral trajectory in a two-dimensional k-space.

Claim 10

A method for reducing motion artifacts in a 3 DFT NMR image which comprises: performing a 3 DFT scan comprised of a series of 3 DFT pulse sequences in which two phase encoding gradients are stepped through values which produce NMR signals that sample a region surrounding the origin of a two-dimensional k-space, such that an area near the origin is sampled initially during the scan and sampling progresses away from the origin as the scan is performed; and employing a motion artifact suppression technique during an initial portion of the scan during which the area near the origin is sampled.

Claim 11

A method for reducing motion artifacts in a 3 DFT NMR image which comprises: performing a 3 DFT scan comprised of a series of 3 DFT pulse sequences in which two phase encoding gradients are stepped through values which produce NMR signals that sample a region surrounding the origin of a two-dimensional k-space, such that an area near the origin is sampled initially during the scan and sampling progresses away from the origin as the scan is performed; and employing a motion artifact suppression technique during an initial portion of the scan during which the area near the origin is sampled.

Claim 14

A method for reducing motion artifacts in a 3 DFT NMR image which comprises: performing a 3 DFT scan comprised of a series of 3 DFT pulse sequences in which two phase encoding gradients are stepped through values which produce NMR signals that sample a region surrounding the origin of a two-dimensional k-space, such that an area near the origin is sampled initially during the scan and sampling progresses away from the origin as the scan is performed; and in which the repetition time (TR) of the 3 DFT pulse sequence is set to a maximum value during the sampling of the region surrounding the origin of k-space and the repetition time (TR) of the 3 DFT pulse sequence is shortened as sampling progresses away from the origin.

Claim 15

A method for reducing motion artifacts in a 3 DFT NMR image which comprises: performing a 3 DFT scan comprised of a series of 3 DFT pulse sequences in which two phase encoding gradients are stepped through values which produce NMR signals that sample a region surrounding the origin of a two-dimensional k-space, such that an area near the origin is sampled initially during the scan and sampling progresses away from the origin as the scan is performed; and in which the repetition time (TR) of the 3 DFT pulse sequence is set to a maximum value during the sampling of the region surrounding the origin of k-space and the repetition time (TR) of the 3 DFT pulse sequence is shortened as sampling progresses away from the origin.