US6487435B2
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Magnetic resonance angiography using undersampled 3D projection imaging
Assignee: Wisconsin Alumni Research Foundation
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Filing: 2001-01-23
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Granted: 2002-11-26
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Expires: 2021-01-23
Abstract
Abstract A 3D projection reconstruction pulse sequence is employed to acquire CEMRA images. In one application of the invention an undersampled, high resolution abdominal CEMRA image is acquired in a single breathhold. In another application of the invention a series of undersampled image frames are acquired during a CEMRA dynamic study Each image is produced by combining peripheral k-space data from adjacent image frames with the central and peripheral k-space data of an acquired image frame.
Inventors
- 👤 Charles A. Mistretta
- 👤 Andrew V. Barger
- 👤 Walter F. Block
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 19:50
CPC Classifications
G; G01; G01R; G01R33/00; G01R33/20; G01R33/44; G01R33/48; G01R33/4818; G01R33/4824; G01R33/54; G01R33/56; G01R33/563; G01R33/28; G01R33/281; G01R33/561; G01R33/5611; G01R33/5619
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
160 words
A method for producing a magnetic resonance image of a patient using a magnetic resonance imaging (MRI) system, the steps comprising: a) operating the MRI system to acquire a k-space image data set using a three-dimensional projection reconstruction pulse sequence that is repeated to sample k-space throughout a three-dimensional k-space volume V, and wherein the three-dimensional projection reconstruction pulse sequence is repeated a sufficient number of times to sample in accordance with the Nyquist condition, a central volume of k-space that is substantially smaller than the volume V but not a sufficient number of times to sample a peripheral region of k-space in accordance with the Nyquist condition; and b) reconstructing an image using substantially the entire, undersampled acquired k-space image data set and wherein the number of repetitions of the three-dimensional projection reconstruction pulse sequence is substantially less than one-half the number of repetitions necessary to fully sample the entire k-space volume V in accordance with the Nyquist condition.
Claim 2
Independent Claim
160 words
A method for producing a magnetic resonance image of a patient using a magnetic resonance imaging (MRI) system, the steps comprising: a) operating the MRI system to acquire a k-space image data set using a three-dimensional projection reconstruction pulse sequence that is repeated to sample k-space throughout a three-dimensional k-space volume V, and wherein the three-dimensional projection reconstruction pulse sequence is repeated a sufficient number of times to sample in accordance with the Nyquist condition, a central volume of k-space that is substantially smaller than the volume V but not a sufficient number of times to sample a peripheral region of k-space in accordance with the Nyquist condition; and b) reconstructing an image using substantially the entire, undersampled acquired k-space image data set and wherein the number of repetitions of the three-dimensional projection reconstruction pulse sequence is substantially less than one-half the number of repetitions necessary to fully sample the entire k-space volume V in accordance with the Nyquist condition.
Claim 3
Independent Claim
198 words
A method for producing a magnetic resonance image of a patient using a magnetic resonance imaging (MRI) system, the steps comprising: a) operating the MRI system to acquire a k-space image data set using a three-dimensional projection reconstruction pulse sequence that is repeated to sample k-space thoughout a k-space volume having a radius R, and wherein the three-dimensional projection reconstruction pulse sequence is repeated a sufficient number of times to sample in accordance with the Nyquist condition, a central region of k-space having a radius r that is substantially smaller than the radius R but not a sufficient number of times to sample a peripheral region of k-space in accordance with the Nyquist condition; and b) reconstructing an image using substantially the entire, undersampled acquired k-space image data set in which step b) includes: i) producing a three-dimensional array of k-space data by regridding the acquired k-space data set; and ii) performing a three-dimensional Fourier transformation on the three-dimensional array of k-space data; and wherein the number of repetitions of three-dimensional projection reconstruction pulse sequence is substantially less than one-half the number of repetitions necessary to fully sample the entire k-space volume in accordance with the Nyquist condition.
Claim 4
Independent Claim
198 words
A method for producing a magnetic resonance image of a patient using a magnetic resonance imaging (MRI) system, the steps comprising: a) operating the MRI system to acquire a k-space image data set using a three-dimensional projection reconstruction pulse sequence that is repeated to sample k-space thoughout a k-space volume having a radius R, and wherein the three-dimensional projection reconstruction pulse sequence is repeated a sufficient number of times to sample in accordance with the Nyquist condition, a central region of k-space having a radius r that is substantially smaller than the radius R but not a sufficient number of times to sample a peripheral region of k-space in accordance with the Nyquist condition; and b) reconstructing an image using substantially the entire, undersampled acquired k-space image data set in which step b) includes: i) producing a three-dimensional array of k-space data by regridding the acquired k-space data set; and ii) performing a three-dimensional Fourier transformation on the three-dimensional array of k-space data; and wherein the number of repetitions of three-dimensional projection reconstruction pulse sequence is substantially less than one-half the number of repetitions necessary to fully sample the entire k-space volume in accordance with the Nyquist condition.
Claim 5
Dependent Claim
17 words
The method as recited in claim 1 in which the resolution of the reconstructed image is isotropic.
Claim 6
Dependent Claim
91 words
The method as recited in claim 1 in which the pulse sequence is performed by: i) producing an rf excitation pulse that produces transverse magnetization in spins located throughout the field of view of the reconstructed image; and ii) acquiring an NMR signal in the presence of a readout gradient to sample k-space in a trajectory that starts at one point on an outer boundary of the sampled k-space volume, passes through the center of k-space and extends out to another point on the outer boundary of the sampled k-space volume.
Claim 7
Dependent Claim
16 words
The method as recited in claim 4 in which the sampling trajectory is a straight line.
Claim 8
Dependent Claim
110 words
The method as recited in claim 1 in which the pulse sequence is performed by: i) producing an rf excitation pulse that produces transverse magnetization in spins located throughout the field of view of the reconstructed image; ii) acquiring an NMR signal in the presence of a readout gradient to sample k-space in a trajectory that extends from one point on an outer boundary of the k-space volume and extends through the center of k-space; and the method further includes the step of synthesizing from the k-space samples acquired in step ii) further k-space samples that extend the trajectory to another point on the outer boundary of the k-space volume.
Claim 9
Dependent Claim
25 words
The method as recited in claim 1 in which step b) includes performing a filtered back projection image reconstruction using the k-space image data set.
Claim 10
Independent Claim
194 words
A method for producing a magnetic resonance angiogram image of selected vasculature in a patient using a magnetic resonance imaging system (MRI), the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample three-dimensional k-space volume along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) with a different readout gradient in three-dimensional projection reconstruction pulse sequence to sample the three-dimensional k-space volume along a different trajectory that extends substantially radially from the center of k-space; e) producing an image data set by repeating step d) to sample k-space throughout a three-dimensional k-space volume with substantially uniform spacing between trajectories and with the spacing between acquired k-space samples from adjacent trajectories at the periphery of the sampled k-space volume being substantially more than twice the spacing necessary to satisfy the Nyquist condition; and f) reconstructing an image of the selected vasculature using substantially all the k-space samples in the acquired image data set.
Claim 11
Independent Claim
194 words
A method for producing a magnetic resonance angiogram image of selected vasculature in a patient using a magnetic resonance imaging system (MRI), the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample three-dimensional k-space volume along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) with a different readout gradient in three-dimensional projection reconstruction pulse sequence to sample the three-dimensional k-space volume along a different trajectory that extends substantially radially from the center of k-space; e) producing an image data set by repeating step d) to sample k-space throughout a three-dimensional k-space volume with substantially uniform spacing between trajectories and with the spacing between acquired k-space samples from adjacent trajectories at the periphery of the sampled k-space volume being substantially more than twice the spacing necessary to satisfy the Nyquist condition; and f) reconstructing an image of the selected vasculature using substantially all the k-space samples in the acquired image data set.
Claim 12
Independent Claim
222 words
A method for producing a magnetic resonance angiogram of selected vasculature in a patient using a magnetic resonance imaging system(MRI) system, the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample k-space along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) with a different readout gradient in the three-dimensional projection reconstruction pulse sequence to sample k-space along a different trajectory that extends substantially radially from the center of k-space; e) producing an image data set by repeating step d) to sample k-space throughout a three-dimensional k-space volume with substantially uniform spacing between trajectories and with the spacing between acquired k-space samples from adjacent trajectories at the periphery of the sampled k-space volume being substantially more than twice the spacing necessary to satisfy the Nyquist condition; f) reconstructing an image of the selected vasculature using substantially all the k-space samples in the acquired image data set; and in which step f) includes: i) producing a three-dimensional array of k-space data by regridding the acquired k-space samples; and ii) performing a three-dimensional Fourier transformation on the three-dimensional array of k-space data.
Claim 13
Independent Claim
222 words
A method for producing a magnetic resonance angiogram of selected vasculature in a patient using a magnetic resonance imaging system(MRI) system, the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample k-space along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) with a different readout gradient in the three-dimensional projection reconstruction pulse sequence to sample k-space along a different trajectory that extends substantially radially from the center of k-space; e) producing an image data set by repeating step d) to sample k-space throughout a three-dimensional k-space volume with substantially uniform spacing between trajectories and with the spacing between acquired k-space samples from adjacent trajectories at the periphery of the sampled k-space volume being substantially more than twice the spacing necessary to satisfy the Nyquist condition; f) reconstructing an image of the selected vasculature using substantially all the k-space samples in the acquired image data set; and in which step f) includes: i) producing a three-dimensional array of k-space data by regridding the acquired k-space samples; and ii) performing a three-dimensional Fourier transformation on the three-dimensional array of k-space data.
Claim 14
Dependent Claim
21 words
The method as recited in claim 8 in which the resolution of the reconstructed image is isotropic throughout the selected vasculature.
Claim 15
Dependent Claim
35 words
The method as recited in claim 8 which includes: timing the performance of steps b) through e) such that the acquired NMR signals are enhanced by the arrival of contrast agent in the selected vasculature.
Claim 16
Dependent Claim
53 words
The method as recited in claim 8 which includes, repeating steps b) through e) to acquire additional image data sets as the contrast agent flows into the selected vasculature, and step f) includes, combining k-space samples from a plurality of acquired image data sets, and reconstructing said image using the combined k-space samples.
Claim 17
Dependent Claim
35 words
The method as recited in claim 12 in which successively acquired image data sets sample different locations in k-space and k-space samples from successive image data sets are combined and used to reconstruct said image.
Claim 18
Dependent Claim
32 words
The method as recited in claim 13 in which the k-space samples from one acquired image data set are combined with peripheral region k-space samples from a successively acquired image data set.
Claim 19
Dependent Claim
42 words
The method as recited in claim 13 in which image data sets from three different and interleaved locations in k-space are successively and repeatedly acquired, and k-space samples from three successive image data sets are combined and used to reconstruct said image.
Claim 20
Independent Claim
265 words
A method for producing a magnetic resonance angiogram of selected vasculature in a patient using a magnetic resonance imaging system (MRI) system, the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample k-space along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) with a different readout gradient in the three-dimensional projection reconstruction pulse sequence to sample k-space along a different trajectory that extends substantially radially from the center of k-space; e) producing an image data set by repeating step d) to sample k-space throughout a three-dimensional k-space volume with substantially uniform spacing between trajectories and with the spacing between acquired k-space samples from adjacent trajectories at the periphery of the sampled k-space volume being substantially more than twice the spacing necessary to satisfy the Nyquist condition; and f) repeating steps b) through e) to acquire additional image data sets as the contrast agent flows into the selected vasculature in which successively acquired image data sets sample from three different and interleaved locations in k-space g) combining k-space samples from a plurality of acquired image data sets and reconstructing an image using the combined k-space samples; and in which all the k-space samples from the second of said three successive image data sets are combined with peripheral region k-space samples from the first and the third of said three successive image data sets.
Claim 21
Independent Claim
265 words
A method for producing a magnetic resonance angiogram of selected vasculature in a patient using a magnetic resonance imaging system (MRI) system, the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample k-space along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) with a different readout gradient in the three-dimensional projection reconstruction pulse sequence to sample k-space along a different trajectory that extends substantially radially from the center of k-space; e) producing an image data set by repeating step d) to sample k-space throughout a three-dimensional k-space volume with substantially uniform spacing between trajectories and with the spacing between acquired k-space samples from adjacent trajectories at the periphery of the sampled k-space volume being substantially more than twice the spacing necessary to satisfy the Nyquist condition; and f) repeating steps b) through e) to acquire additional image data sets as the contrast agent flows into the selected vasculature in which successively acquired image data sets sample from three different and interleaved locations in k-space g) combining k-space samples from a plurality of acquired image data sets and reconstructing an image using the combined k-space samples; and in which all the k-space samples from the second of said three successive image data sets are combined with peripheral region k-space samples from the first and the third of said three successive image data sets.
Claim 22
Dependent Claim
27 words
The method as recited in claim 16 in which the spacing between k-space samples in a central region of each image data set satisfies the Nyquist condition.
Claim 23
Dependent Claim
51 words
The method as recited in claim 12 in which the three-dimensional projection reconstruction pulse sequence produces a velocity encoding gradient; successively acquired image data sets are velocity encoded for spin motion along different axes; and k-space samples from successively acquired image data sets are combined and used to reconstruct said image.
Claim 24
Dependent Claim
38 words
The method as recited in claim 18 in which image data sets with three different velocity encoding directions are successively acquired, and k-space samples from three successive image data sets are combined and used to reconstruct said image.
Claim 25
Dependent Claim
22 words
The method as recited in claim 13 in which the radial k-space sampling trajectories of the different image data sets are interleaved.
Claim 26
Dependent Claim
42 words
The method as recited in claim 8 in which the k-space sampling trajectories acquired in step c) extend from the center of k-space in substantially opposite directions therefrom and to substantially opposite points on an outer boundary of the sampled k-space volume.
Claim 27
Independent Claim
212 words
A method for producing a magnetic resonance angiogram image of selected vasculature in a patient using a magnetic resonance imaging system (MRI), the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample a three-dimensional k-space volume along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) a plurality of times with a different readout gradient in the three-dimensional projection reconstruction pulse sequence each repetition to sample a first set of trajectories; e) repeating steps b) and c) a plurality of time with a different readout gradient in each repetition to sample a second set of trajectories; f) repeating steps b) and c) a plurality of times with a different readout gradient in each repetition to sample a third set of trajectories; g) combining sampled k-space data in the second set of trajectories with sampled k-space data from the first and third sets of trajectories that is located in a peripheral region of said three-dimensional k-space volume; and h) reconstructing an image of the selected vasculature using the combined k-space data.
Claim 28
Independent Claim
212 words
A method for producing a magnetic resonance angiogram image of selected vasculature in a patient using a magnetic resonance imaging system (MRI), the steps comprising: a) injecting the patient with a contrast agent which flows into the selected vasculature; b) operating the MRI system to perform a three-dimensional projection reconstruction pulse sequence; c) acquiring an NMR signal produced by spins in the selected vasculature to sample a three-dimensional k-space volume along a trajectory that extends substantially radially from the center of k-space; d) repeating steps b) and c) a plurality of times with a different readout gradient in the three-dimensional projection reconstruction pulse sequence each repetition to sample a first set of trajectories; e) repeating steps b) and c) a plurality of time with a different readout gradient in each repetition to sample a second set of trajectories; f) repeating steps b) and c) a plurality of times with a different readout gradient in each repetition to sample a third set of trajectories; g) combining sampled k-space data in the second set of trajectories with sampled k-space data from the first and third sets of trajectories that is located in a peripheral region of said three-dimensional k-space volume; and h) reconstructing an image of the selected vasculature using the combined k-space data.
Claim 29
Dependent Claim
24 words
The method as recited in claim 22 which includes performing step e) at an optimal moment when the contrast flows into said selected vasculature.
References Cited (Backward Citations)
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