Magnetic resonance angiography using undersampled 3D projection imaging
AssigneeWisconsin Alumni Research Foundation
InventorsCharles A. Mistretta, Andrew V. Barger, Walter F. Block
Life of this patent
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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.
Claims21
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 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;
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- 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 in accordance with the Nyquist condition.
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;
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- f) reconstructing an image of the selected vasculature using substantially all the k-space samples in the acquired image data set.
Dependencies are inferred from the claim text.