Pin diode current reduction for MRI transmit coils

Patent metadata

Field	Value
Publication number	US-12292489-B2
Application number	US-202318179475-A
Country	US
Kind code	B2
Filing date	Mar 7, 2023
Priority date	Mar 16, 2022
Publication date	May 6, 2025
Grant date	May 6, 2025

Abstract

Various embodiments of the present disclosure are directed to a magnetic resonance imaging (MRI) radio frequency (RF) coil comprising a current-control circuit. A conductive trace forms a coil inductor and comprises a first trace segment and a second trace segment separated by the current-control circuit, which comprises a first reactive element and a circuit branch. The first reactive element is electrically coupled from the first trace segment to the second trace segment, and the circuit branch is electrically coupled in parallel with the first reactive element. The circuit branch comprises a second reactive element and a sub-circuit branch electrically coupled in parallel. The sub-circuit branch comprises a third reactive element and an electronic switch (e.g., a PIN diode) electrically coupled in series. The first reactive element and the third reactive element are one of capacitive and inductive, and the second reactive element is another one of capacitive and inductive.

First claim

What is claimed is:

1. A magnetic resonance imaging (MRI) radio frequency (RF) coil, comprising:
a conductive trace forming a coil inductor and comprising a first trace segment and a second trace segment separated by a separation;
a first reactive element separating the first trace segment from the second trace segment, and electrically coupled from the first trace segment to the second trace segment, at the separation; and
a circuit branch separating the first trace segment from the second trace segment, and electrically coupled in parallel with the first reactive element, at the separation, wherein the circuit branch comprises:
a second reactive element; and
a sub-circuit branch electrically coupled in parallel with the second reactive element, wherein the sub-circuit branch comprises a third reactive element and an electronic switch that are electrically coupled in series;

wherein the first reactive element and the third reactive element are one of capacitive and inductive, and wherein the second reactive element is another one of capacitive and inductive.

2. The MRI RF coil of claim 1 , wherein the second reactive element and the third reactive element are configured to resonate at a resonant frequency when the electronic switch is ON, and wherein the first reactive element and the second reactive element are configured to resonate at the resonant frequency when the electronic switch is OFF.

3. The MRI RF coil of claim 1 , wherein the conductive trace comprises a third trace segment extending from the first trace segment and the second trace segment, and wherein the third trace segment forms the first reactive element.

4. The MRI RF coil of claim 1 , wherein the first reactive element is a discrete capacitor.

5. The MRI RF coil of claim 1 , wherein the first reactive element and the third reactive element are inductive, and wherein the second reactive element is capacitive.

6. The MRI RF coil of claim 1 , wherein the first reactive element and the third reactive element are capacitive, and wherein the second reactive element is inductive.

7. The MRI RF coil of claim 1 , wherein the circuit branch consists essentially of the electronic switch, the second reactive element, and the third reactive element.

8. The MRI RF coil of claim 1 , wherein the circuit branch further comprises:
a fourth reactive element electrically coupled in series with a parallel combination of the sub-circuit branch and the second reactive element.

9. The MRI RF coil of claim 1 , wherein the MRI RF coil is a birdcage coil, and wherein the first trace segment and the second trace segment form a rung of the birdcage coil.

10. The MRI RF coil of claim 1 , wherein the MRI RF coil is a birdcage coil, and wherein the first trace segment and the second trace segment form a ring of the birdcage coil.

11. A magnetic resonance imaging (MRI) system comprising a radio frequency (RF) coil, wherein the RF coil comprises:
a conductive trace forming a coil inductor and comprising a first trace segment and a second trace segment;
a first reactive element separating the first trace segment from the second trace segment and electrically coupled from the first trace segment to the second trace segment; and
a circuit branch electrically coupled in parallel with the first reactive element, wherein the circuit branch comprises:
a second reactive element;

a sub-circuit branch electrically coupled in parallel with the second reactive element, wherein the sub-circuit branch comprises a third reactive element and an electronic switch that are electrically coupled in series; and
a cylindrical former around which the RF coil is circumferentially arranged,
wherein the second reactive element, the third reactive element, and the electronic switch form a first loop having a first resonant frequency, and wherein the first reactive element and the second reactive element form a second loop having a second resonant frequency that is the same as the first resonant frequency.

12. The MRI system of claim 11 , wherein the conductive trace comprises a third trace segment and a fourth trace segment electrically coupled in parallel and extending from the first trace segment to the second trace segment, and wherein the third and fourth trace segments collectively form the first reactive element and are separated from each other by a gap.

13. The MRI system of claim 12 , wherein the conductive trace comprises a fifth trace segment between the third and fourth trace segments and electrically coupled in series with a parallel combination of the sub-circuit branch and the third reactive element.

14. The MRI system of claim 11 , wherein the conductive trace comprises:
a third trace segment extending from the first trace segment to the second trace segment and forming the first reactive element; and
a fourth trace segment electrically coupled in series with a parallel combination of the sub-circuit branch and the third reactive element, wherein the fourth trace segment overlaps with the third trace segment.

15. A method for magnetic resonance imaging (MRI), comprising:
providing a MRI radio frequency (RF) coil, comprising:
a conductive trace forming a coil inductor and comprising a first trace segment and a second trace segment;
a first reactive element separating the first trace segment from the second trace segment and electrically coupled from the first trace segment to the second trace segment; and
a circuit branch electrically coupled in parallel with the first reactive element, wherein the circuit branch comprises a second reactive element and a sub-circuit branch electrically coupled in parallel with the second reactive element, wherein the sub-circuit branch comprises a third reactive element and an electronic switch electrically coupled in series; and
performing MRI on a scan target to generate an image of the scan target, wherein the performing comprises exciting nuclei in the scan target at a working frequency with the MRI RF coil and receiving MR signals from the scan target;
wherein the second and third reactive elements resonate at the working frequency during the exciting, and wherein the first and second reactive elements resonate at the working frequency during the receiving.

16. The method of claim 15 , wherein the electronic switch is ON during the exciting, and wherein the second and third reactive elements resonate at the working frequency to create a high impedance directing current in the conductive trace through the first reactive element.

17. The method of claim 15 , wherein the electronic switch is OFF during the receiving, and wherein the first and second reactive elements resonate at the working frequency to create a high impedance blocking current flow in the conductive trace.

18. The method of claim 15 , wherein the MRI RF coil is a local transmit/receive coil, and wherein the method further comprises:
arranging the MRI RF coil on the scan target.

19. The method of claim 15 , wherein the MRI RF coil is a whole-body coil (WBC) of an MRI scanner and is circumferentially arranged around a bore of the MRI scanner, and wherein the method further comprises:
arranging the scan target in the bore of the MRI scanner.

20. The method of claim 15 , wherein the first reactive element and the third reactive element are capacitive, and wherein the second reactive element is inductive.

Assignees

• Quality Electrodynamics Llc

Inventors

• Yang Xiaoyu

Classifications

• G01R33/34076

  Birdcage coils · CPC title

• G01R33/3657 Primary

  Decoupling of multiple RF coils wherein the multiple RF coils do not have the same function in MR, e.g. decoupling of a transmission coil from a receive coil · CPC title

• G01R33/365

  Decoupling of multiple RF coils wherein the multiple RF coils have the same function in MR, e.g. decoupling of a receive coil from another receive coil in a receive coil array, decoupling of a transmission coil from another transmission coil in a transmission coil array · CPC title

• G01R33/341 Primary

  comprising surface coils · CPC title