Patent ID: 6954067

Claim:
A method for producing a magnetic resonance image indicative of spin motion, the steps comprising: a) acquiring an NMR signal with an MRI system using a three-dimensional projection reconstruction pulse sequence which includes: producing an RF excitation field; producing a motion encoding gradient field G M directed along a motion encoding axis; and acquiring an NMR signal while producing a readout gradient to sample a three-dimensional k-space volume along a trajectory that extends substantially radially from the center of k-space; b) producing a first k-space data set by repeating step a) using different readout gradients to sample k-space throughout the three-dimensional k-space volume along different trajectories with substantially uniform spacing between trajectories; c) producing a second k-space data set by repeating steps a), and b) using a different motion encoding gradient G M ; d) reconstructing a first phase image from the first k-space data set; e) reconstructing a second phase image from the second k-space data set; f) producing a velocity image by combining the first and second phase images, in which the initial motion encoding gradient field G M has a first moment +M 1 and the second motion encoding gradient field G M has an opposite first moment −M 1 and step f) is performed by subtracting the first and second phase images; and which includes repeating steps a)-c) a plurality of times using motion encoding gradient fields G M having different valued first moments +M 1 and −M 1 for each repeat, producing a corresponding plurality of first k-space data sets and a corresponding plurality of second k-space data sets, and wherein step f) includes subtracting corresponding k-space data sets in said plurality of first and second k-space data sets to form a plurality of subtracted k-space data sets, and performing a one-dimensional Fourier transformation along corresponding locations in the plurality of subtracted k-space data sets to produce velocity bin data sets.