System and method for controlling motion effects in magnetic resonance imaging (MRI) images

1. A method for generating magnetic resonance imaging (MRI) images, the steps of the method comprising:

a) preparing an MRI system having a defined field of view (FOV) to perform a dynamic contrast enhanced imaging study of a subject during motion of the subject;

b) directing the MRI system to perform the dynamic contrast enhanced imaging study by:

i) exciting a two-dimensional (2D) slice within a portion of the defined FOV and oriented in a selected direction relative to the motion of the subject;

ii) acquiring imaging data from the 2D slice by sampling k-space in a pseudorandom manner using sampling trajectories extending between a center of k-space and peripheral areas of k-space;

iii) sliding the 2D slice to another portion of the defined FOV at a velocity selected to be greater than a velocity of the motion of the subject;

c) repeating b) for each of a plurality of 2D slices; and

d) reconstructing the imaging data to form at least one image of the subject.

2. The method as recited in claim 1 , wherein b)ii) includes acquiring data weighted to measure perfusion in the subject.

3. The method as recited in claim 1 , wherein the motion of the subject is caused by respiration of the subject.

4. The method as recited in claim 1 , wherein a) includes creating a timing plan for b) that accounts for movement of contrast agent dynamics and respiratory motion to thereby perform b)i) and b)ii) while the contrast agent washes into the 2D slice and within a predetermined portion of a respiratory cycle of the subject.

5. The method as recited in claim 1 , wherein the sampling trajectories are formed as one of radial lines and variable density Cartesian sampling.

6. The method as recited in claim 1 , wherein c) includes sweeping the 2D slice from superior to inferior over a contiguous volume coverage within the FOV.

7. The method as recited in claim 6 , wherein in-plane k-space samples are collected using golden angle radial sampling.

8. The method as recited in claim 1 , wherein i) includes linearly varying an excitation frequency.

9. The method as recited in claim 1 , wherein i) includes directing the MRI system to produce a radio frequency pulse that is not slice-selective to saturate inflow blood or impart a three-dimensional (3D) T1 steady state before exciting the 2D slice to acquire the imaging data in ii).

10. A magnetic resonance imaging (MRI) system, comprising:

a magnet system configured to generate a polarizing magnetic field about a field of view (FOV) of the MRI system that receives a subject having received a dose of a contrast agent;

gradient coils configured to establish at least one magnetic gradient field to the polarizing magnetic field;

a radio frequency (RF) system configured to apply an RF field to the subject and to receive magnetic resonance signals therefrom;

a computer system programmed to:

a) direct the RF system and the gradient coils to:

i) excite a slice; and

ii) sample k-space to acquire k-space data in a pseudorandom manner and with a sampling trajectory of extending from center of k-space to peripheral areas of the k-space and sliding the slice to another portion of the defined FOV at a velocity selected to be greater than a velocity of motion of the subject;

b) repeat step a) for each of a number of sliding slices; and

c) reconstruct at least one MRI image from the k-space data that spans a portion of the subject showing contrast dynamics spanning the number of sliding slices.

11. The system as recited in claim 10 , wherein the contrast dynamics include perfusion of at least one organ in an abdomen of the subject.

12. The system as recited in claim 10 , wherein c) includes reconstructing the at least one MRI image such that artifacts induced by the motion of the subject are reflected as geometric distortions.

13. The system as recited in claim 10 , wherein the sampling trajectory is one of a radial line and a variable density Cartesian sampling.

14. The system as recited in claim 10 , wherein the computer is further configured to track a physiological cycle of the subject and coordinate i) and ii) within the physiological cycle.

15. The system as recited in claim 10 , wherein the sampling trajectory is radial sampling performed in the pseudorandom order and employing a golden-angle.

16. The system as recited in claim 10 , wherein i) includes linearly varying an excitation frequency.

17. The system as recited in claim 10 , wherein the computer system is further programmed to direct the RF system to produce RF pulse prior to exciting the slice.

18. The system as recited in claim 17 , wherein the RF pulse is used to saturate spins flowing into the slice or impart a three-dimensional T1 steady state to the slice.

19. The system as recited in claim 10 , wherein the computer system is further programmed to register images associated with each of the number of sliding slices to reconstruct the at least one MRI image showing contrast dynamics spanning the number of sliding slices.

20. The system as recited in claim 10 , wherein the computer system is further programmed to coordinate a) relative to a respiratory cycle of the subject.