Systems and methods for magnetic resonance imaging

• US 8,406,849 B2
• Filed: 04/02/2007
• Issued: 03/26/2013
• Est. Priority Date: 03/31/2006
• Status: Expired due to Fees

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: University of Utah Research Foundation (State of Utah)
• Inventors: Jeong, Eun-Kee, Parker, Dennis L., Kholmovski, Evgueni G., Choi, Kim Seong-Eun
• Primary Examiner(s): Jung, Unsu
• Assistant Examiner(s): SANTOS RODRIGUEZ, JOSEPH M
• Application Number:
  US11/732,382
• Publication Number:
  US 20070249929A1
• Time in Patent Office: 2,185 Days
• Field of Search: 600/410, 600/413, 324/300, 324/307, 324/309
• US Class Current: 600/410
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: G01R 33/4806 Functional imaging of brain activation
• CPC Class Codes: G01R 33/5615 Echo train techniques involving acquiring plural, differently encoded, echo signals after one RF excitation, e.g. using gradient refocusing in echo planar imaging [EPI], RF refocusing in rapid acquisition with relaxation enhancement [RARE] or using both RF and gradient refocusing in gradient and spin echo imaging [GRASE]
• CPC Class Codes: G01R 33/5616 using gradient refocusing, e.g. EPI
• CPC Class Codes: G01R 33/56341 Diffusion imaging
• CPC Class Codes: G01R 33/56509 due to motion, displacement or flow, e.g. gradient moment nulling G01R33/567 takes precedence
• CPC Class Codes: G01R 33/56536 due to magnetic susceptibility variations
• CPC Class Codes: G01R 33/5676 Gating or triggering based on an MR signal, e.g. involving one or more navigator echoes for motion monitoring and correction

Abstract

Methods and apparatus for operating an MRI system is provided. The disclosure provides a diffusion-prepared driven-equilibrium preparation for an imaging volume and acquiring 3-dimensional k-space data from said prepared volume by a plurality of echoplanar readouts of stimulated echoes. An excitation radio-frequency signal and first and second inversion RF signals are provided to define a field-of-view (FOV).

Claims

1. A method for operating an MRI system in diffusion imaging, comprising the steps of:

providing a single Diffusion-Prepared Driven-Equilibrium preparation (DPDE) for a localized imaging volume comprising a first excitation RF pulse followed by first and second successive RF inversion pulses, said first and second successive RF inversion pulses determining the localized imaging volume for imaging with the first inversion pulse inverting magnetization and the second inversion pulse and accompanying phase encoding gradient restoring magnetization to a non-selected portion of said localized imaging volume;

acquiring Diffusion-weighted MRI imaging (DWI) and Diffusion-tensor MRI imaging (DTI) 3-dimensional k-space data from the prepared localized imaging volume by applying a plurality of stimulated echo planar imaging (EPI) pulse sequence acquisitions of a selected portion of said localized imaging volume, in response to said single diffusion-prepared driven-equilibrium preparation; and

reconstructing and generating medical images of said localized imaging volume using the acquired DWI and DTI 3-dimensional k-space data, in response to said single diffusion-prepared driven-equilibrium preparation.

2. The method of claim 1, wherein

the selected portion of said localized imaging volume comprises a slab being imaged and said plurality of stimulated echo planar imaging pulse sequence acquisitions acquire said slab as center-out k-space segments and

said first excitation RF pulse and the first and second successive RF inversion pulses comprise 90 degree, 180 degree and 180 degree pulses respectively.

3. The method of claim 1, wherein said plurality of stimulated echo planar imaging pulse sequence acquisitions acquire interleaved k-space segments and employ a corresponding plurality of variable flip angle RF excitation pulses progressively changed to reduce T₁ decay-related blurring in a slice direction.

4. The method of claim 1, wherein said MRI system is operated for diffusion-weighted MR imaging (DWI) and said plurality of stimulated echo planar imaging pulse sequence acquisitions acquire a plurality of interleaved k-space segments with an individual segment being acquired using an excitation RF pulse, rephasing crusher gradient, an echo-planar imaging readout gradient, and a rewinding or spoiler gradient.

5. The method of claim 1, wherein said MRI system is operated for diffusion tensor MR imaging (DTI).

6. The method of claim 1, wherein the step of acquiring 3-dimensional k-space data comprises center-out acquisition of 3-dimensional k-space data segments for reconstruction of an individual image slice, in response to said single diffusion-prepared driven-equilibrium preparation.

7. A control system for an MRI apparatus for use in diffusion imaging, comprising:

a control processor configured to generate one or more instructions for;

providing a single Diffusion-Prepared Driven-Equilibrium (DPDE) for a localized imaging volume comprising a first excitation RF pulse followed by first and second successive RF inversion pulses, said first and second successive RF inversion pulses determining the localized imaging volume with the first inversion pulse inverting magnetization and the second inversion pulse and accompanying phase encoding gradient restoring magnetization to a non-selected portion of said localized imaging volume;

acquiring 3-dimensional Diffusion-weighted MRI imaging (DWI) and Diffusion-tensor MRI imaging (DTI) k-space data from the prepared localized imaging volume by applying a plurality of stimulated echo planar imaging (EPI) pulse sequence acquisitions of a selected portion of said localized imaging volume, in response to said single diffusion-prepared driven-equilibrium preparation; and

reconstructing and generating medical images of said localized imaging volume using the acquired DWI and DTI 3-dimensional k-space data, in response to said single diffusion-prepared driven-equilibrium preparation.

8. The system of claim 7, wherein

the selected portion of said localized imaging volume comprises a slab being imaged and said plurality of stimulated echo planar imaging pulse sequence acquisitions acquire said slab as center-out k-space segments and

said first excitation RF pulse and the first and second successive RF inversion pulses comprise 90 degree, 180 degree and 180 degree pulses respectively.

9. The system of claim 7, wherein said plurality of stimulated echo planar imaging pulse sequence acquisitions acquire interleaved k-space segments and employ a corresponding plurality of variable flip angle RF excitation pulses progressively changed to reduce T₁ decay-related blurring in a slice direction.

10. The system of claim 7, wherein said MRI apparatus is for diffusion-weighted MR imaging (DWI) and said plurality of stimulated echo planar imaging pulse sequence acquisitions acquire a plurality of interleaved k-space segments with an individual segment being acquired using an excitation RF pulse, rephasing crusher gradient, an echo-planar imaging readout gradient, and a rewinding or spoiler gradient.

11. The system of claim 7, wherein said MRI apparatus is configured for diffusion tensor MR imaging (DTI).

12. The system of claim 7, wherein said acquiring of 3-dimensional k-space data comprises center-out acquisition of 3-dimensional k-space data segments for reconstruction of an individual image slice, in response to said single diffusion-prepared driven-equilibrium preparation.