Method for simultaneous multi-slice magnetic resonance imaging using single and multiple channel receiver coils

Patent metadata

Field	Value
Publication number	US-9414766-B2
Application number	US-201113581209-A
Country	US
Kind code	B2
Filing date	Feb 25, 2011
Priority date	Feb 25, 2010
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A method for reconstructing a plurality of images depicting a subject from image data that is simultaneously acquired from a corresponding plurality of slice locations with a magnetic resonance imaging (MRI] system is provided. Image data is acquired following the application of radio frequency (RF] energy to the plurality of slice locations. The RF energy is tailored to provide a different phase to each of the plurality of slice locations. Reference image data is also acquired for each slice location following the application of RF energy that has the same phase as is used to excite the respective slice location for the acquisition of the image data. Aliased images are reconstructed from the image data, and reference images are reconstructed from the reference image data. Using both of these image sets, an unaliased image is produced for each of the plurality of slice locations.

First claim

The invention claimed is:

1. A method for reconstructing a plurality of images depicting a subject from k-space data that is simultaneously acquired from a corresponding plurality of slice locations with a magnetic resonance imaging (MRI) system, the steps of the method comprising:
a) simultaneously acquiring k-space data from a plurality of slice locations with the MRI system following application of radio frequency (RF) energy to the plurality of slice locations, the RF energy applying a different phase to each of the plurality of slice locations;
b) acquiring reference k-space data from one of the plurality of slice locations with the MRI system following application of RF energy to the one of the plurality of slice locations, the RF energy applying a phase to the one of the plurality of slice locations corresponding to the different phase applied to the corresponding slice location in step a);
c) repeating step b) for each of the different phases of the RF energy applied in step a) to acquire reference k-space data for each of the plurality of slice locations;
d) reconstructing aliased images from the k-space data acquired in step a);
e) reconstructing reference images from the reference k-space data acquired in steps b) and c), wherein each reference image is a complex-valued image that depicts the subject; and
f) producing an unaliased image for each of the plurality of slice locations using the aliased images reconstructed in step d) and the reference images reconstructed in step e).

2. The method as recited in claim 1 in which step f) includes solving a system of equations that relates a magnitude of the reference images, a phase of the reference images, and the aliased images to each of the unaliased images.

3. The method as recited in claim 2 in which solving the system of equations in step f) includes using a least squares estimation.

4. The method as recited in claim 2 in which solving the system of equations in step f) includes using an encoding matrix having entries that are a product between the magnitude each of the reference images and at least one of a sine and a cosine of the phase of the same one of the reference images.

5. The method as recited in claim 1 in which step f) includes correcting the aliased images for phase drifts before producing the unaliased images.

6. The method as recited in claim 1 in which the k-space data acquired in step a) is a time course of k-space data.

7. The method as recited in claim 6 in which the time course of k-space data is functional image data representative of neuronal activity occurring in the subject during the acquisition of the image data in step a).

8. The method as recited in claim 1 in which the k-space data acquired in step a) is acquired with a multiple channel receiver coil array, the reference data acquired in step b) is acquired for one of the multiple channels in the multiple channel receiver coil array, and step c) includes repeating step b) for each channel in the multiple channel receiver coil array before repeating step b) for each of the plurality of slice locations.

9. The method as recited in claim 8 in which step f) includes solving a system of equations that relates a magnitude of the reference images, a phase of the reference images, and the aliased images to each of the unaliased images.

10. The method as recited in claim 9 in which step f) includes producing an average reference image for each slice location by averaging respective ones of the reference images corresponding to reference k-space data acquired from the respective slice location by each of the different coils in the multiple channel receiver coil array.

11. The method as recited in claim 10 in which the system of equations includes an encoding matrix having entries that are a product between the magnitude each of the average reference images and at least one of a sine and a cosine of the phase of the same one of the average reference images.

12. The method as recited in claim 8 in which step f) includes:
i) summing respective ones of the reference images corresponding to reference k-space data acquired from different coils in the multiple channel receiver coil array for a given slice location;
ii) calculating a phase difference between the summed reference image produced in step f)i) and the aliased image corresponding to the given slice location;
iii) determining a phase correction factor using the calculated phase difference; and
iv) applying the phase correction factor to the corresponding aliased image.

13. The method as recited in claim 12 in which step f)iii) includes fitting the calculated phase difference to a polynomial that includes terms that relate to phase drifts arising from noise and from heat transfer in gradient coils that form a part of the MRI system.

14. The method as recited in claim 1 in which the RF energy applied in step a) is tailored by performing a Fourier transform on a desired slice profile that defines a location and a phase for each of the plurality of slice locations.

15. The method as recited in claim 1 further comprising:
g) performing a spin conditioning pulse sequence before acquiring k-space data in step a).

16. The method as recited in claim 15 in which the spin conditioning pulse sequence performed in step g) provides at least one of fat suppression and diffusion weighting.

17. The method as recited in claim 1 in which the k-space data acquired in step a) is undersampled k-space data and step f) includes producing the unaliased images using a reconstruction technique that accounts for a partial sample of k-space.

18. The method as recited in claim 17 in which the reconstruction technique that accounts for partial sampling of k-space includes at least one of SENSE and GRAPPA.

19. The method as recited in claim 1 in which the k-space data acquired in step a) is acquired during a period of time such that the k-space data represents a time course of image frames, and step f) includes reconstructing a plurality of image frames for each of the plurality of slice locations, the plurality of image frames for each of the plurality of slice locations thereby forming a time series of images for the respective one of the plurality of slice locations.

20. The method as recited in claim 1 in which the subject is a brain and plurality of slice locations substantially cover an entire volume of the brain.

21. The method as recited in claim 1 further comprising selecting a thickness of each of the plurality of slice locations before acquiring the k-space data in step a).

Assignees

• Jesmanowicz Andrzej
• Li Shi-Jiang
• Hyde James S
• Medical College Wisconsin Inc

Inventors

• Jesmanowicz Andrzej
• Li Shi-Jiang
• Hyde James S

Classifications

• A61B5/055 Primary

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• G01R33/4835

  of multiple slices · CPC title

• G01R33/56545

  caused by finite or discrete sampling, e.g. Gibbs ringing, truncation artefacts, phase aliasing artefacts · CPC title

• G01R33/4806

  Functional imaging of brain activation · CPC title

• G01R33/5616

  using gradient refocusing, e.g. EPI · CPC title