Method for rapid whole brain magnetic resonance imaging with contrast preparation

Patent metadata

Field	Value
Publication number	US-9915717-B2
Application number	US-201113995869-A
Country	US
Kind code	B2
Filing date	Dec 20, 2011
Priority date	Dec 20, 2010
Publication date	Mar 13, 2018
Grant date	Mar 13, 2018

Abstract

A method for acquiring image data from a plurality of slice locations in a subject with a magnetic resonance imaging (MRI) system is provided. The method includes directing the MRI system to perform a pulse sequence that includes performing a contrast preparation module configured to generate contrast-encoded longitudinal magnetization and an image encoding module configured to acquire image data from multiple slice locations substantially simultaneously. The contrast preparation module generally includes tipping longitudinal magnetization into the transverse plane to produce transverse magnetization, generating contrast-prepared transverse magnetization by establishing an image contrast in the transverse magnetization, and tipping the contrast-prepared magnetization back along the longitudinal axis to produce the contrast-encoded longitudinal magnetization.

First claim

The invention claimed is:

1. A method for simultaneously acquiring image data from a plurality of slice locations in a subject with a magnetic resonance imaging (MRI) system, the steps of the method comprising:
acquiring image data simultaneously from a plurality of slice locations contained in a plurality of subvolumes of a volume-of-interest in a subject by directing an MRI system to perform a pulse sequence that includes:
a) performing a contrast preparation module configured to generate contrast-prepared magnetization simultaneously in the plurality of subvolumes by applying at least one multiband radio frequency (RF) pulse to the volume-of-interest;
b) performing an image encoding module configured to acquire image data simultaneously from the plurality of slice locations contained in the plurality of subvolumes, the acquired image data having an image contrast indicated by the contrast-prepared magnetization; and
reconstructing at least one image from the acquired image data, wherein the at least one image includes contrast indicated by the contrast-prepared magnetization.

2. The method as recited in claim 1 in which the contrast-prepared magnetization generated in step a) is contrast-prepared longitudinal magnetization, and in which step a) includes applying the at least one multiband RF pulse to the volume-of-interest to:
i) tip longitudinal magnetization in the plurality of subvolumes into a transverse plane to produce transverse magnetization;
ii) generate contrast-prepared transverse magnetization by establishing an image contrast in the transverse magnetization; and
iii) tip the contrast-prepared transverse magnetization in the plurality of subvolumes back along a longitudinal axis to produce the contrast-prepared longitudinal magnetization.

3. The method as recited in claim 1 in which the image encoding module performed in step b) includes spatially multiplexing magnetic resonance signals from the plurality of slice locations.

4. The method as recited in claim 3 in which spatially multiplexing the magnetic resonance signals includes applying at least one multiband RF excitation pulse to simultaneously excite each of the plurality of slice locations.

5. The method as recited in claim 1 in which the image encoding module performed in step b) includes temporally multiplexing magnetic resonance signals from the plurality of slice locations.

6. The method as recited in claim 4 in which temporally multiplexing the magnetic resonance signals includes performing a simultaneous image refocusing (SIR).

7. The method as recited in claim 1 in which the image encoding module performed in step b) includes spatially multiplexing magnetic resonance signals from the plurality of slice locations and temporally multiplexing magnetic resonance signals from the plurality of slice locations.

8. The method as recited in claim 1 in which the contrast preparation module performed in step a) includes:
applying a first multiband RF pulse that rotates longitudinal magnetization in the plurality of subvolumes by a flip angle into a transverse plane to produce transverse magnetization;
waiting a first time period having a duration equal to a preselected delay time;
applying a multiband refocusing RF pulse to refocus the transverse magnetization in the plurality of subvolumes;
waiting a second time period having a duration equal to the preselected delay time, thereby producing contrast-prepared transverse magnetization in the plurality of subvolumes; and
applying a second multiband RF pulse having the flip angle and a one-hundred eighty degree phase shift relative to the first multiband RF pulse, so that the contrast-prepared transverse magnetization is tipped back along a longitudinal axis to produce contrast-prepared longitudinal magnetization in the plurality of subvolumes.

9. The method as recited in claim 8 in which the contrast preparation module performed in step b) further includes applying diffusion-encoding gradients during the first and second time periods so that the contrast-prepared transverse magnetization is diffusion-weighted transverse magnetization.

10. The method as recited in claim 1 in which the contrast preparation module performed in step a) includes:
applying a first multiband RF pulse that rotates longitudinal magnetization in the plurality of subvolumes by a flip angle into a transverse plane to produce transverse magnetization;
waiting a first time period having a duration equal to a preselected delay time;
applying a first multiband refocusing RF pulse to refocus the transverse magnetization in the plurality of subvolumes;
waiting a second time period having a duration equal to twice the preselected delay time;
applying a second multiband refocusing RF pulse to refocus the transverse magnetization in the plurality of subvolumes;
waiting a third time period having a duration equal to the preselected delay time, thereby producing contrast-prepared transverse magnetization in the plurality of subvolumes; and
applying a second multiband RF pulse having the flip angle and a one-hundred eighty degree phase shift relative to the first multiband RF pulse, so that the contrast-prepared transverse magnetization is tipped back along a longitudinal axis to produce contrast-prepared longitudinal magnetization in the plurality of subvolumes.

11. The method as recited in claim 10 in which the first multiband refocusing RF pulse, the second time period, and the second multiband refocusing RF pulse are repeated a plurality of times before waiting the third time period.

12. The method as recited in claim 10 in which the first and second multiband refocusing RF pulses are both at least one of adiabatic multiband refocusing RF pulses and adiabatic multiband inversion RF pulses.

13. The method as recited in claim 1 in which the at least one multiband RF pulse in the contrast preparation module is a segmented adiabatic multiband B1-independent rotation RF pulse.

14. The method as recited in claim 13 in which the segmented adiabatic multiband B1-independent rotation RF pulse includes a first component, a first delay time period, a second component, a second delay time period, and a third component, wherein:
the first component rotates longitudinal magnetization in the plurality of subvolumes into a transverse plane to produce transverse magnetization;
the second component refocuses the transverse magnetization; and
the third component rotates the transverse magnetization back along a longitudinal axis.

15. The method as recited in claim 14 in which the segmented adiabatic multiband B1-independent rotation RF pulse includes a first component, a first delay time period, a second component, a second delay time period, a third component, a third delay time period, and a fourth component, wherein:
the first component rotates longitudinal magnetization in the plurality of subvolumes into a transverse plane to produce transverse magnetization;
the second component and the third component both refocus the transverse magnetization; and
the fourth component rotates the transverse magnetization back along a longitudinal axis.

16. The method as recited in claim 1 in which the contrast preparation module performed in step a) includes:
applying a first multiband RF pulse that rotates longitudinal magnetization in the plurality of subvolumes by a flip angle into a transverse plane to produce transverse magnetization;
waiting a first time period having a duration equal to a preselected delay time;
applying a multiband refocusing RF pulse to refocus the transverse magnetization i

Assignees

• Ugurbil Kamil
• Univ Minnesota

Inventors

• Ugurbil Kamil

Classifications

• G01R33/4835 Primary

  of multiple slices · CPC title

• G01R33/5602

  by filtering or weighting based on different relaxation times within the sample, e.g. T1 weighting using an inversion pulse · CPC title

• G01R33/561 Primary

  by reduction of the scanning time, i.e. fast acquiring systems, e.g. using echo-planar pulse sequences · CPC title