High frequency coil and magnetic resonance image pickup device

Patent metadata

Field	Value
Publication number	US-10641845-B2
Application number	US-201515504681-A
Country	US
Kind code	B2
Filing date	Aug 7, 2015
Priority date	Sep 5, 2014
Publication date	May 5, 2020
Grant date	May 5, 2020

Abstract

A technique for reconciling large sensitivity area and high sensitivity for deep part in a multi-channel array coil of an MRI apparatus without complicating the configuration, and realizing both higher speed imaging and high image quality is provided. An RF coil (array coil) of a magnetic resonance imaging apparatus comprising a plurality of subcoils is provided. At least one of the subcoils is a first subcoil of which resonance frequency as that of the subcoil alone differs from magnetic resonance frequency. The first subcoil is adjusted so that it magnetically couples with a second subcoil, which is at least one other subcoil, and thus resonates at the same frequency as the magnetic resonance frequency. Input and output terminals of the first subcoil and the second subcoil are connected to different low input and output impedance signal processing circuits, respectively.

First claim

The invention claimed is:

1. A radio frequency coil comprising:
a first subcoil that has a first loop coil part consisting of a conductor, and is configured to transmit and receive a magnetic resonance signal,
a second subcoil that has a second loop coil part consisting of a conductor, and is configured to transmit and receive a magnetic resonance signal,
wherein the first subcoil is disposed such that a resonance frequency of the first subcoil alone is different from a nuclear magnetic resonance frequency, which is a frequency of a magnetic resonance signal of an object for transmission and reception, and
wherein the first subcoil magnetically couples with the second subcoil to form circling electric current paths in a loop of the first loop coil part and a loop of the second loop coil part, and to resonate at the nuclear magnetic resonance frequency.

2. The radio frequency coil according to claim 1 ,
wherein the second subcoil is disposed such that a resonance frequency of the second subcoil alone is different from the nuclear magnetic resonance frequency, and
wherein the second subcoil magnetically couples with the first subcoil to form circling electric current paths in a loop of the first loop coil part and a loop of the second loop coil part, and to resonate at the nuclear magnetic resonance frequency.

3. The radio frequency coil according to claim 1 ,
wherein the first subcoil further comprises a first magnetic coupling-adjusting part that connects the first loop coil part and a first low impedance signal processing circuit to which the first subcoil is connected,
wherein the first loop coil part comprises:
a first series capacitor that is serially inserted with respect to an inductor component of the loop,
a first parallel capacitor that is serially inserted with respect to the inductor component, and makes the first loop coil part to be a parallel resonant circuit,
wherein the second subcoil further comprises a second magnetic coupling-adjusting part that connects the second loop coil part and a second low impedance signal processing circuit to which the second subcoil is connected,
wherein the second loop coil part comprises:
a second series capacitor that is serially inserted with respect to inductor component of the loop,
a second parallel capacitor that is serially inserted with respect to the inductor component, and makes the second loop coil part to be a parallel resonant circuit,
wherein the first magnetic coupling-adjusting part comprises at least one of a capacitor and an inductor as a first adjustment circuit element,
wherein the second magnetic coupling-adjusting part comprises at least one of a capacitor and an inductor as a second adjustment circuit element, and
wherein the first subcoil and the second subcoil are adjusted by adjusting values of the first adjustment circuit element, the second adjustment circuit element, the first series capacitor, the second series capacitor, the first parallel capacitor, and the second parallel capacitor.

4. The radio frequency coil according to claim 1 ,
wherein the first subcoil and the second subcoil are disposed in at such positions that the first subcoil and the second subcoil magnetically couple with each other.

5. The radio frequency coil according to claim 1 ,
wherein the first subcoil further comprises a first coupling inductor,
wherein the second subcoil further comprises a second coupling inductor, and
wherein the first subcoil and the second subcoil magnetically couple with each other with the first coupling inductor and the second coupling inductor.

6. The radio frequency coil according to claim 1 ,
wherein the radio frequency coil further comprises a third subcoil that has a third loop coil part consisting of a conductor, and can transmit and receive a magnetic resonance signal, and
wherein the third subcoil is disposed and adjusted so that a resonance frequency of the third subcoil alone is different from the nuclear magnetic resonance frequency and, and the third subcoil magnetically couples with the second subcoil to form circling electric current paths in a loop of the third loop coil part and a loop of the second loop coil part, and to resonate at the nuclear magnetic resonance frequency.

7. The radio frequency coil according to claim 1 ,
wherein the radio frequency coil further comprises a fourth subcoil that has a fourth loop coil part consisting of a conductor, and is configured to transmit and receive a magnetic resonance signal,
wherein the fourth subcoil is disposed so that the fourth loop coil part has overlapping regions that overlap with the first loop coil part and the second loop coil part, respectively, and
wherein areas of the overlapping regions are determined so that the fourth subcoil does not magnetically couple with the first subcoil and the second subcoil.

8. The radio frequency coil according to claim 1 ,
wherein the first subcoil and the second subcoil are connected to a low input impedance signal processing circuit, respectively, and function as a receiving coil that receives the magnetic resonance signal.

9. The radio frequency coil according to claim 1 ,
wherein the first subcoil and the second subcoil are connected to a low output impedance signal processing circuit, and function as a transmitting coil that transmits the magnetic resonance signal.

10. A magnetic resonance imaging apparatus comprising:
a static magnetic field formation part for forming a static magnetic field,
a gradient magnetic field formation part for forming a gradient magnetic field,
a radio frequency magnetic field generation part for generating a radio frequency magnetic field,
a transmitting coil for irradiating the radio frequency magnetic field on a test subject,
a receiving coil for detecting a magnetic resonance signal from the test subject, and
an image reconstruction part for reconstructing an image from the detected magnetic resonance signal, wherein:
at least one of the transmitting coil and the receiving coil is the radio frequency coil according to claim 1 , and
the transmitting coil and the receiving coil each comprise a magnetic coupling-preventing circuit that prevents magnetic coupling between the transmitting coil and the receiving coil.

Assignees

• Hitachi Ltd

Inventors

• Otake Yosuke
• Ochi Hisaaki
• Iwasawa Kohjiro

Classifications

• G01R33/3635

  Multi-frequency operation · CPC title

• G01R33/54

  Signal processing systems, e.g. using pulse sequences {; Generation or control of pulse sequences; Operator console} · CPC title

• G01R33/3657

  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

• G01R33/3415

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

• G01R33/3815

  with superconducting coils, e.g. power supply therefor · CPC title