RF coil and magnetic resonance imaging apparatus

• US 20030164704A1
• Filed: 02/26/2003
• Published: 09/04/2003
• Est. Priority Date: 03/01/2002
• Status: Active Grant

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Yokogawa Medical Systems Limited (GE Aerospace)
• Inventors: Yoshida, Masaru
• Granted Patent: US 6,879,159 B2
• Time in Patent Office: Days
• US Class Current: 324/322
• CPC Class Codes: G01R 33/3415 comprising arrays of sub-coils , i.e. phased-array coils with flexible receiver channels
• CPC Class Codes: G01R 33/365 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

Abstract

For the purpose of changing the geometry of and spacing between loop coils incorporated into an RF coil without moving the RF coil, loops 200-220 having a geometry optimized for a square sum method employing a phased array, and second small loops 202-222 having a geometry optimized for a sensitivity encoding method are switched by switching elements 24-54 and 25-55 for an open/close operation using a diode 330, and at the same time, first decoupling means 230 and 231 and second decoupling means 240 and 241 are switched. Thus, an operator is not required to replace the RF coil positioned on a cradle, and the loops 200-220 for the square sum method employing a phased array and the second small loops for the sensitivity encoding method can be switched by electronic switching and can be used as RF coils.

Claims

1. An RF coil comprising a plurality of loops, wherein said loops comprise:

a plurality of types of decoupling device for preventing mutual magnetic coupling between adjacent ones of said loops; and

a switching device for switching between said loops corresponding to said types simultaneously with switching between said types of said decoupling device.

2. An RF coil comprising a plurality of loops each divided into a plurality of small loops, wherein said loops and said small loops comprise:

a different decoupling device for preventing mutual magnetic coupling between adjacent ones of said loops and between adjacent ones of said small loops; and

a switching device for switching between said loops and said small loops simultaneously with switching between said different decoupling device.

3. The RF coil of claim 2, wherein said decoupling device comprise first decoupling device formed by disposing adjacent pairs of said loops with approximately 10% of the area of said loops overlapped.

4. The RF coil of claim 2, wherein each said loop is comprised of a first small loop generally including a portion overlapped by said first decoupling device, and a second small loop formed from a portion excluding said first small loop of said loop.

5. The RF coil of claim 2, wherein said decoupling device comprise second decoupling device that connects said second small loops using an inductor or a capacitor.

6. The RF coil of claim 2, wherein said switching device comprises a first switching element on a loop line of said first small loop shared by said loop.

7. The RF coil of claim 2, wherein said switching device comprises a second switching element on a loop line shared by said first and second small loops.

8. The RF coil of claim 2, wherein said switching element is an open/close element that operates to open and close said loops and said second small loops.

9. The RF coil of claim 2, wherein said switching device comprises open/close control device that alternately open/close-controls said first and second switching elements to switch between said first and second decoupling device simultaneously with switching between said loops and said second small loops.

10. The RF coil of claim 2, wherein said open/close control device conducts the same open/close control for the plurality of said loops.

11. The RF coil of claim 2, wherein said open/close element is a parallel resonant circuit incorporating therein a diode.

12. The RF coil of claim 2, wherein said open/close element is a relay.

13. The RF coil of claim 2, wherein said switching device comprises a third switching element in an end portion of a loop line shared by said first and second small loops.

14. The RF coil of claim 2, wherein said third switching element is a selecting element that operates to make a selection.

15. The RF coil of claim 2, wherein said switching device comprises a selection control device that selects between said loops and said second small loops by said third switching element.

16. The RF coil of claim 2, wherein said selection control device conducts the same selection control for the plurality of said loops and for the plurality of said second small loops.

17. The RF coil claim 2, wherein said selecting element is a relay.

18. The RF coil of claim 2, wherein said second small loops have a geometry of and spacing between the second small loops in which the S/N ratio is optimized for conducting a sensitivity encoding method.

19. A magnetic resonance imaging apparatus comprising:

a static magnetic field generating device for generating a static magnetic field;

a gradient magnetic field generating device for generating a gradient magnetic field;

an RF coil for transmitting and receiving an RF signal; and

a control device for controlling said gradient magnetic field generating device and said RF coil, wherein said RF coil having a plurality of loops each divided into a plurality of small loops comprises;

a plurality of decoupling device for preventing mutual magnetic coupling between adjacent ones of said loops and between adjacent ones of said small loops; and

a switching device for switching between the plurality of said decoupling device simultaneously with switching between said loops and said small loops.

20. The magnetic resonance imaging apparatus of claim 19, wherein:

said magnetic resonance imaging apparatus further comprises a transmitting section that transmits an RF signal to said static magnetic field and is controlled by said control section; and

said RF coil comprises magnetic coupling preventing device for preventing magnetic coupling with said transmitting device.