High frequency coil unit and magnetic resonance imaging apparatus

Patent metadata

Field	Value
Publication number	US-9541614-B2
Application number	US-201214001221-A
Country	US
Kind code	B2
Filing date	Apr 6, 2012
Priority date	Apr 11, 2011
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

The present invention is directed to an elliptical birdcage coil which reduces time and effort upon manufacturing and production cost, with less variations in performance. There is provided a high frequency coil unit made up of the elliptical birdcage coil having plural capacitors arranged at least on either of the ring conductors and the rung conductors, the capacitance of the plural capacitors being uniform with respect to each conductor type on which the capacitors are placed. In this elliptical birdcage coil, a value of inductance and arrangement of the ring conductors and the rung conductors are determined in such a manner that the capacitance of the capacitors becomes identical with respect to each conductor type on which the capacitors are arranged.

First claim

What is claimed is:

1. A magnetic resonance imaging apparatus comprising:
a coil, the coil comprising:
two elliptical ring conductors having an arc shape at least partially, the two elliptical ring conductors being arranged in parallel with each other;
a plurality of linear conductors, both ends of each of the plurality of linear conductors being connected to the elliptical ring conductors, respectively; and

a plurality of capacitors, each of the plurality of capacitors comprising at least one capacitor, and each of the plurality of capacitors having a substantially identical capacitance,
wherein at least one of the plurality of capacitors is arranged one by one on a linear conductor and/or on an arc-shaped conductor, the arc-shaped conductor forming a part of the elliptical ring conductor, and the arc-shaped conductor being placed between connection points of the linear conductors, which are adjacent,
wherein the plurality of linear conductors are arranged line symmetrically with respect to a major axis and a minor axis of the elliptical ring conductor, and
wherein a width of each of the plurality of linear conductors and a distance between the centers of the adjacent linear conductors increase along with going away from the minor axis toward the major axis of the elliptical ring conductor.

2. The magnetic resonance imaging apparatus according to claim 1 ,
wherein the linear conductor and the elliptical ring conductor are shaped like a sheet having a width.

3. The magnetic resonance imaging apparatus according to claim 1 ,
wherein the coil further comprises either of two feeding ports and four feeding ports for feeding RF (radiofrequency) signals to the coil, and
wherein the feeding ports are arranged at positions line-symmetrical with respect to either one of the major axis and the minor axis of the elliptical ring like conductor, and as for two of the feeding ports being adjacent in a circumferential direction of the elliptical ring conductor, when power is fed to one feeding port, amplitude of RF current flowing in the other feeding port is minimized.

4. The magnetic resonance imaging apparatus according to claim 1 , wherein the coil further comprises a shield outside the elliptical ring conductor, the plurality of linear conductors being covered with the shield.

5. The magnetic resonance imaging apparatus according to claim 4 , wherein a distance between the elliptical ring like conductor and the shield is constant with respect to the circumferential direction of the elliptical ring like conductor.

6. The magnetic resonance imaging apparatus according to claim 4 , wherein a distance between the elliptical ring conductor and the shield becomes shorter along with going away from the minor axis toward the major axis of the elliptical ring conductor.

7. The magnetic resonance imaging apparatus according to claim 1 , further comprising:
a magnetic decoupling circuit for preventing mutual magnetic coupling,
wherein the magnetic decoupling circuit is arranged on either of the linear conductor or the elliptical ring conductor.

8. The magnetic resonance imaging apparatus according to claim 7 , wherein the magnetic decoupling circuit is a PIN diode.

9. The magnetic resonance imaging apparatus according to claim 7 , wherein the magnetic decoupling circuit comprises a circuit where the PIN diode and an inductor are connected in series, and a capacitor is connected in parallel with the circuit.

10. The magnetic resonance imaging apparatus according to claim 1 , further comprising:
an RF (radiofrequency) magnetic field signal generator which generates an RF magnetic field signal; and
a signal processor which subjects a detection signal to a signal processing,
wherein the coil irradiates a test subject with the RF magnetic field signal inputted from the RF magnetic field signal generator, detects a magnetic resonance signal issued from the test subject, and outputs the magnetic resonance signal as the detection signal to the signal processor.

11. The magnetic resonance imaging apparatus according to claim 7 , further comprising:
an RF (radiofrequency) magnetic field signal generator which generates an RF magnetic field signal and a reception coil which detect a magnetic resonance signal issued from a test subject, and outputting the signal as a detection signal,
wherein the coil irradiates the test subject with the RF magnetic field signal inputted from the RF magnetic field signal generator.

12. A magnetic resonance imaging apparatus comprising:
a coil, the coil comprising:
two elliptical ring conductors having an arc at least partially, the two elliptical ring like conductors being arranged in parallel with each other;
a plurality of linear conductors, both ends of each of the plurality of linear conductors being connected to the elliptical ring conductors, respectively; and
a plurality of capacitors, each of the plurality of capacitors comprising at least one capacitor and each of the plurality of capacitors having a substantially identical capacitance,
wherein at least one of the plurality of capacitors is arranged one by one on a linear conductor and/or on an arc-shaped conductor, the arc-shaped conductor forming a part of the elliptical ring conductor, and the arc-shaped conductor being placed between connection points of the linear conductors which are adjacent, and
wherein the plurality of linear conductors are arranged line symmetrically with respect to a major axis and a minor axis of the elliptical ring conductor, and
wherein a width of each of the plurality of linear conductors increases along with going away from the minor axis toward the major axis of the elliptical ring conductor.

13. The magnetic resonance imaging apparatus according to claim 12 ,
wherein each of the linear conductor and the elliptical ring conductor is shaped like a sheet having a width.

14. The magnetic resonance imaging apparatus according to claim 12 ,
wherein the coil further comprises either of two feeding ports and four feeding ports for feeding RF (radiofrequency) signals to the coil, and
wherein the feeding ports are arranged at the positions line-symmetrical with respect to either one of the major axis and the minor axis of the elliptical ring conductor, and as for two of the feeding ports, which are adjacent in a circumferential direction of the elliptical ring conductor, when power is fed to one of the two feeding ports, amplitude of RF current flowing in the other of the two feeding ports is minimized.

15. A magnetic resonance imaging apparatus comprising:
a coil, the coil comprising:
two elliptical ring conductors having an arc shape at least partially, the two elliptical ring conductors being arranged in parallel with each other;
a plurality of linear conductors, both ends of each of the plurality of linear conductors being connected to the elliptical ring conductors, respectively; and
a plurality of capacitors, each of the plurality of capacitors comprising at least one capacitor and each of the plurality of capacitors having a substantially identical capacitance,
wherein at least one of the capacitors is arranged one by one, on the linear conductor and/or on an arc-shaped conductor forming a part of the elliptical ring conductor, the arc-shaped conductor being placed between connection points of the linear conductors, which are adjacent, and
wherein the plurality of linear conductors are arranged line symmetrically with respect to a major axis and a minor axis of the elliptical ring conductor, and
wherein an electrical phase difference between two arc-shaped conductors, which are ad

Assignees

• Soutome Yoshihisa
• Bito Yoshitaka
• Habara Hideta
• Hitachi Ltd

Inventors

• Soutome Yoshihisa
• Bito Yoshitaka
• Habara Hideta

Classifications

• A61B5/055

  involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging · CPC title

• G01R33/34 Primary

  Constructional details, e.g. resonators {, specially adapted to MR} · CPC title

• G01R33/34076 Primary

  Birdcage coils · CPC title