Dual gradient echo pulse sequence using interleaved spiral-out spiral-in k-space trajectories

• US 20060062731A1
• Filed: 09/17/2004
• Published: 03/23/2006
• Est. Priority Date: 09/17/2004
• Status: Active Grant

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford University)
• Inventors: Bammer, Roland, Mosley, Michael
• Granted Patent: US 7,368,910 B2
• Time in Patent Office: Days
• US Class Current: 424/9.300
• CPC Class Codes: A61B 5/0263 using NMR
• CPC Class Codes: A61K 49/06 Nuclear magnetic resonance [NMR] contrast preparations; Magnetic resonance imaging [MRI] contrast preparations
• 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
• CPC Class Codes: G01R 33/56341 Diffusion imaging

Abstract

Measurements of functional, hemographic, and blood flow parameters use a multiple echo or spin echo gradient pulse sequence whereby an early echo is acquired near the beginning of the pulse sequence which avoids saturation effects and a later echo near the end of the pulse sequence which can provide information with more sensitivity to a contrast agent for a susceptibility weighted image.

Claims

1. A method of magnetic resonance imaging of functional, hemodynamic, or blood flow parameters comprising the steps of:

a) applying pulse echo RF excitation pulses to excite nuclear spins,

b) applying a multiple echo or spin echo gradient pulse sequence whereby an early echo is acquired near the beginning of the gradient pulse sequence and a later echo is acquired near the end of the gradient pulse sequence, and

c) using echo signals to derive spatial and temporal maps of quantitative functional, hemodynamic, or blood flow parameters.

2. The method of claim 1 wherein the gradient pulse sequence provides k-space trajectories that over sample the origin of k-space and provide spatial and temporal RF coil sensitivities information for use in parallel image reconstruction.

3. The method of claim 2 as applied for use in dynamic susceptibility contrast (DSC) perfusion weighted imaging (PWI).

4. The method of claim 2 wherein k-space sampling is dense near k-space origin as applied for phase or motion navigation for motion sensitive imaging.

5. The method of claim 2 wherein k-space sampling is dense away from k-space origin as applied to functional MRI.

6. The method of claim 2 wherein the early echo avoids saturation effects and provides a spatial or temporal information of an arterial input function, and the later echo provides information with more sensitivity to a contrast agent for a susceptibility weighted image.

7. The method of claim 6 wherein quantitative T2* spatial and temporal measurements are obtained.

8. The method of claim 7 wherein the measurements are used to derive quantitative functional, hemodynamic, or blood flow information.

9. The method of claim 6 wherein quantitative T2 spatial and temporal measurements are obtained.

10. The method of claim 6 wherein T2 or T2* spatial and temporal measurements are acquired as a function of repetition time TR, and are used to eliminate confounding T1 relaxation effects.

11. The method of claim 6 wherein the information is acquired by control of a spin echo or a gradient echo to derive spatial and temporal information to differentiate between large blood vessel and small blood vessel data contributions to the quantitative functional, hemodynamic, or blood flow information.

12. The method of claim 6 wherein the information is acquired by control of a spin echo or a gradient echo to derive coherent and incoherent quantitative information to differentiate between large blood vessel and small blood vessel data contributions.

13. The method of claim 6 wherein the dual gradient pulse sequence traverses a k-space trajectory in interleaved spiral out-spiral in paths to create a refocused gradient echo which can be combined with a RF refocused spin echo.

14. The method of claim 13 wherein the pulse sequence is repeated with variable density trajectories.

15. The method of claim 13 wherein images can be created from a single shot RF pulse or from interleaved multiple RF shots.

16. The method of claim 13 wherein the k-space trajectories provide self navigating.

17. The method of claim 13 wherein the pulse sequence is used to acquire separately spaced even echoes to derive rephased functional, hemodynamic, or blood flow information.

18. The method of claim 2 wherein the k-space origin is sufficiently densely sampled to create low resolution imaging from which spatial and temporal RF coil sensitivities can be derived.

19. The method of claim 2 wherein the k-space origin is sufficiently densely sampled to derive coil weights required for k-space based parallel imaging techniques.

20. The method of claim 19 wherein spatial and temporal changes in coil sensitivity from coil motion or body motion from shot to shot are derived.