Technique for simultaneous acquisition of multiple independent MR imaging volumes with optimization of magnetic field homogeneity for spin preparation

• US 7,034,530 B2
• Filed: 06/28/2002
• Issued: 04/25/2006
• Est. Priority Date: 06/28/2002
• Status: Expired due to Fees

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: General Electric Company
• Inventors: Ahluwalia, Baldev S., Maier, Cynthia F., Angelos, Elisabeth C.
• Primary Examiner(s): Gutierrez, Diego
• Assistant Examiner(s): Vargas, Dixomara
• Application Number:
  US10/185,211
• Publication Number:
  US 20040000907A1
• Time in Patent Office: 1,397 Days
• Field of Search: 324/309, 324/307
• US Class Current: 324/309
• CPC Class Codes: G01R 33/3415 comprising arrays of sub-coils , i.e. phased-array coils with flexible receiver channels
• CPC Class Codes: G01R 33/5611 Parallel magnetic resonance imaging, e.g. sensitivity encoding [SENSE], simultaneous acquisition of spatial harmonics [SMASH], unaliasing by Fourier encoding of the overlaps using the temporal dimension [UNFOLD], k-t-broad-use linear acquisition speed-up technique [k-t-BLAST], k-t-SENSE structural details of arrays of sub-coils G01R33/3415

Abstract

An MR imaging pulse sequence provides a method for simultaneous data acquisition from more than one independently prescribed volume while providing optimized field uniformity during both the magnetization preparation and data acquisition parts of the acquisition. The method is based on the use of a multi-element array coil where individual RF coil elements are more sensitive to one of the separate volumes of interest than to the other volumes. In the example of breast imaging, one scenario would have two coil elements that are designed to be most sensitive to the signal from the left breast, and two coil elements that are designed to be most sensitive to the signal from the right breast. An optimized pulse sequence and reconstruction technique is used to simultaneously acquire two separate sagittal imaging volumes corresponding to the left and right breasts with optimized fat suppression.

Claims

1. An MR imaging pulse sequence and reconstruction method that comprises the steps of:

identifying a first imaging volume;

providing a first coil element sensitive to the first imaging volume identifying a second imaging volume;

providing a second coil element sensitive to the second imaging volume;

setting the shim currents to optimize the field homogeneity over the first imaging volume;

using a first spectral-spatial RF pulse to selectively invert the magnetintion from adipose tissue in the first imaging volume;

setting the shim currents to optimize the field homogeneity over the second imaging volume;

using a second spectral-spatial RE pulse to selectively invert the magnetization from adipose tissue in the second imaging volume;

exciting the magnetization in both imaging volumes simultaneously;

acquiring the MR data simultaneously from the first and second imaging volumes;

reconstructing the MR signal from the first imaging volume;

reconstructing the MR signal from the second imaging volume; and

using the SENSE algorithm in the slice direction.

2. The method of claim 1 wherein the shim settings are applied to optimize field uniformity to ensure that resonant frequency of the adipose tissue is limited to the bandwidth of the inversion pulse.

3. A method for acquiring MR imaging data simultaneously from more than one independently prescribed volume that comprises the steps of:

identifying a first sagittal volume;

providing RF coils sensitive to said first said sagittal volume for acquiring an image from said first sagittal volume;

setting the shim currents to optimize the field homogeneity over the first sagittal volume;

using a first spectral-spatial RF pulse to selectively invert the magnetization from adipose tissue in the first sagittal volume,

identifying a second sagittal volume;

providing RF coils sensitive to said second said sagittal volume for acquiring an image from said second sagittal volume;

setting the shim currents to optimize field homogeneity over the second sagittal volume;

using a second spectral-spatial RF pulse to selectively invert the magnetization from adipose tissue in the second sagittal volume;

exciting the magnetization in both imaging volumes simultaneously;

playing out a train of alpha pulses;

phase encoding and acquiring gradient echoes;

limiting the field of view of the first RF coil to the first imaging volume;

limiting the field of view of the second RF coil to the second imaging volume;

acquiring the MR data simultaneously from the first and second imaging volumes; and

reconstructing the MR signal using the SENSE algorithm in the slice direction;

wherein an image corresponding only to the first volume and an image corresponding only to the second volume is reconstructed.

4. The method of claim 3 including the step of setting shim currents to optimize field uniformity aver the second imaging volume prior to the beginning of the pulse sequence wherein filed uniformity is optimized over the volume that is effected by the spectral-spatial pulse.

5. The method of claim 4 wherein the shim settings are applied to optimize field uniformity to ensure that resonant frequency of the adipose tissue is limited to the bandwidth of the inversion pulse.

6. The method of claim 5 wherein the shim settings are applied to optimize field uniformity to ensure that resonant frequency of the adipose tissue is limited to the bandwidth of the inversion pulse.

7. A method for the simultaneous acquisition of high-resolution sagittal volumes in a patient during MR imaging that comprises the steps of:

identifying a plurality of sagittal volumes;

providing at least one RF coil, each of said RF coils being sensitive to a particular sagittal volume and being used for acquiring an image from each of said sagittal volumes;

setting the shim currents to optimize the field homogeneity over each sagittal volume;

sequentially using a spectral-spatial RF pulse to selectively invert the magnetization from adipose tissue in each sagittal volume;

exciting the magnetization in both imaging volumes simultaneously;

playing out a train of alpha pulses; and

phase encoding and acquiring gradient echoes;

limiting the field of view of the first RF coil to the first imaging volume;

limiting the field of view of the second RF coil to the second imaging volume;

acquiring the MR data simultaneously from the first and second imaging volumes;

reconstructing the MR signal using the SENSE algorithm in the slice direction;

wherein an image corresponding to each volume is reconstructed.

8. The method of claim 7 including the step of setting shim currents to optimize field uniformity over each imaging volume prior to the beginning of the pulse sequence wherein field uniformity is optimized aver the volume that is effected by the spectral-spatial pulse.

9. The method of claim 8 wherein the shim settings are applied to optimize field uniformity to ensure that resonant frequency of the adipose tissue is limited to the bandwidth of the inversion pulse.

10. The method of claim 7 wherein the sagittal volumes are breast volumes, carotid arteries, shoulders, hips, temporomandibular joints, separate specimens or multiple samples of any clinical type.

11. A method for acquiring MR imaging data from a patient, said acquisition being conducted simultaneously of two sagittal volumes that may include breast volumes, carotid arteries, shoulders, hips, temporomandibular joints, separate specimens or multiple samples of any clinical type, comprising the steps of:

providing RF coils sensitized to the first sagittal volume for acquiring an image from said first sagittal volume inverting the magnetization from adipose tissue in the first sagittal volume with a first spectral-spatial RF pulse;

setting the shim currents to optimize the field homogeneity over the first sagittal volume;

providing RF coils sensitized to the second sagittal volume for acquiring an image from said second sagittal volume inverting the magnetization from adipose tissue in the second sagittal volume with a second spectral-spatial RF pulse, setting the shim currents to optimize the field homogeneity over the second sagittal volume;

exciting the magnetization in the first and second imaging volumes simultaneously using a train of alpha pulses;

decoupling the RF coils sufficiently that the first volume coils receive signal only from the first volume and the second volume coils receive signal only from the second volume;

acquiring the MR data simultaneously from the first and second imaging volumes; and

reconstructing the MR signal;

wherein an image corresponding only to the first volume and an image corresponding only to the second volume is reconstructed.

12. A method for acquiring MR imaging data from a patient, said acquisition being conducted simultaneously of two sagittal volumes that may include breast volumes, carotid arteries, shoulders, hips, temporomandibular joints, separate specimens or multiple samples of any clinical type, comprising the steps of:

providing one or more RF coil elements sensitized to the first sagittal volume for acquiring an image from said first sagittal volume;

identifying a second sagittal volume;

providing one or more RF coil elements sensitized to the first sagittal volume for acquiring an image from said second sagittal volume inverting the magnetization from adipose tissue in the first sagittal volume with a first spectral-spatial RF pulse;

setting the shim currents to optimize the field homogeneity over the first sagittal volume;

inverting the magnetization from adipose tissue in the second sagittal volume with a second spectral-spatial RF pulse;

setting the shim currents to optimize field homogeneity over the second sagittal volume;

exciting the magnetization in the first and second imaging volumes simultaneously using a train of alpha pulses;

recovering the longitudinal magnetization of adipose tissue;

decoupling the RF coils sufficiently that the first volume elements receive signal only from the first volume and the second volume elements receive signal only from the second volume; and

reconstructing the MR signal;

wherein an image corresponding only to the first volume and an image corresponding only to the second volume is reconstructed.