Artificially structured B1 magnetic field generator for MRI and NMR devices

Patent metadata

Field	Value
Publication number	US-9927503-B2
Application number	US-201414334368-A
Country	US
Kind code	B2
Filing date	Jul 17, 2014
Priority date	Jul 17, 2014
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

Described embodiments include an apparatus, and a method. An apparatus includes an array of at least two artificially structured electromagnetic unit cells. The at least two artificially structured electromagnetic unit cells are configured to generate a pulse of radiofrequency magnetic field B 1 orientated transverse to the quasistatic magnetic field B 0 parallel to the z-axis of the bore of a MRI or NMR device by transforming an incident pulse of radiofrequency electromagnetic waves. The generated pulse having magnetic field intensity sufficient to excite a detectable magnetic resonance in magnetically active nuclei located within at least a portion of an examination region located within the bore. The apparatus includes a radiofrequency electromagnetic wave conducting structure configured to distribute a received pulse of radiofrequency electromagnetic waves as an incident pulse of radiofrequency electromagnetic waves to the at least two artificially structured electromagnetic unit cells.

First claim

What is claimed is:

1. An apparatus comprising:
a radiofrequency electromagnetic wave conducting structure configured to distribute a received pulse of radiofrequency electromagnetic waves as an incident pulse of radiofrequency electromagnetic waves to an array of at least two artificially structured electromagnetic unit cells; and
the array of the at least two artificially structured electromagnetic unit cells,
the at least two artificially structured sub-wavelength electromagnetic unit cells configured to generate a pulse of radiofrequency magnetic field B 1 orientated transverse to a quasistatic magnetic field B 0 parallel to a z-axis of a bore of a magnetic resonant imaging or a nuclear magnetic resonant device by transforming the incident pulse of radiofrequency electromagnetic waves, and
the generated pulse having a magnetic field intensity sufficient to excite a detectable magnetic resonance in magnetically active nuclei located within at least a portion of an examination region located within the bore.

2. The apparatus of claim 1 , wherein the magnetic field B 0 is created by a primary magnet of the magnetic resonant imaging or the nuclear magnetic resonant device.

3. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells includes at least two metamaterial unit cells.

4. The apparatus of claim 1 , wherein a unit cell of the at least two artificially structured sub-wavelength electromagnetic unit cells includes an artificially structured metamaterial unit cell with a strong magnetic response.

5. The apparatus of claim 4 , wherein a unit cell of the at least two artificially structured sub-wavelength electromagnetic unit cells includes an artificially structured, highly inductive metamaterial unit cells.

6. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells includes at least two periodically arranged, artificially structured electromagnetic unit cells.

7. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells include split ring resonator inserts optimized to generate a highly inductive electromagnetic near field.

8. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells respectfully include a spiral insert optimized to generate a high inductance density.

9. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells respectively include a conical helical insert optimized to generate a high inductance density.

10. The apparatus of claim 9 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells respectively include three orthogonally oriented conical helical inserts optimized to generate a high inductance density.

11. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells includes a pyramidal helical insert optimized to generate a high inductance density.

12. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are configured to induce a B 1 magnetic field component orthogonal to the z-axis.

13. The apparatus of claim 12 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are respectively configured to induce a first B 1 magnetic field component orthogonal to the z-axis and a second B 1 magnetic field component orthogonal to the first B 1 magnetic field component.

14. The apparatus of claim 12 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are configured to induce magnetic field B 1 components in all three mutually orthogonal orientations.

15. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells include a sub-wavelength arrangement of magnetic dipole unit cells.

16. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells include a sub-wavelength arrangement of magnetic multipole unit sources.

17. The apparatus of claim 1 , wherein the array is configured to generate a near-field region magnetic field B 1 .

18. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are configured to generate a pulse of a tunable radiofrequency magnetic field B 1 .

19. The apparatus of claim 18 , wherein the tunable radiofrequency magnetic field B 1 includes a frequency, amplitude, or polarization tunable radiofrequency magnetic field B 1 .

20. The apparatus of claim 1 , wherein the array is configured to be coaxially disposed about the z-axis.

21. The apparatus of claim 1 , wherein the array includes an arcuate shape dimensioned to be mounted or positioned within at least a portion of the bore of the magnetic resonant imaging or the nuclear magnetic resonant device.

22. The apparatus of claim 1 , wherein the array includes two arcuate shaped portions, each dimensioned to be less than 180-degrees of the circumference of the bore, and mounted or positioned facing each other across the z-axis.

23. The apparatus of claim 1 , wherein the array has a cylindrical or an annular shape dimensioned to be mounted or positioned within the bore of the magnetic resonant imaging or the nuclear magnetic resonant device.

24. The apparatus of claim 1 , wherein the array includes two generally planar portions, each configured to be generally mounted or positioned facing the other across the z-axis.

25. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are configured to generate a highly inductive electromagnetic near-field B 1 .

26. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are configured to generate a magnetic field-dominant radiofrequency near-field with magnetic (B 1 ) and electric (E) field intensities such that (B 1 c)/E 1 >1 (where “c” is the speed of light).

27. The apparatus of claim 26 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are configured to generate a magnetic field-dominant RF near-field where (B 1 c)/E 1 >10.

28. The apparatus of claim 1 , wherein the at least two artificially structured sub-wavelength electromagnetic unit cells are configured to generate a magnetic field B 1 that includes a gradient intensity orientated transverse to the z-axis.

29. The apparatus of claim 1 , wherein the pulse of radiofrequency magnetic field B 1 is linearly polarized relative to the z-axis.

30. The apparatus of claim 1 , wherein the pulse of radiofrequency magnetic field B 1 is circularly polarized relative to the z-axis.

31. The apparatus of claim 1 , wherein the array of at least two artificially structured sub-wavelength electromagnetic unit cells is further configured to receive magnetic resonance signals generated by magnetically active nuclei disposed in an examination region of the magnetic resonant imaging or the nuclear magnetic resonant device, and to generate a signal indicative thereof

Assignees

• Elwha Llc

Inventors

• Driscoll Tom
• Smith David R
• Urzhumov Yaroslav A

Classifications

• G01R33/36

  Electrical details, e.g. matching or coupling of the coil to the receiver · CPC title

• G01R33/3614

  RF power amplifiers · CPC title

• G01R33/3621

  NMR receivers or demodulators, e.g. preamplifiers, means for frequency modulation of the MR signal using a digital down converter, means for analog to digital conversion [ADC] or for filtering or processing of the MR signal such as bandpass filtering, resampling, decimation or interpolation · CPC title

• G01R33/345

  of waveguide type (G01R33/343 takes precedence) · CPC title

• G01R33/3415

  comprising arrays of sub-coils {, i.e. phased-array coils with flexible receiver channels} · CPC title