MULTI-RESONANT T/R ANTENNA FOR MR IMAGE GENERATION

• US 20150002156A1
• Filed: 01/03/2013
• Published: 01/01/2015
• Est. Priority Date: 01/17/2012
• Status: Active Grant

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Leussler, Christoph, Mazurkewitz, Peter, Keupp, Jochen
• Granted Patent: US 10,451,692 B2
• Time in Patent Office: Days
• US Class Current: 324/322
• CPC Class Codes: G01R 33/34 Constructional details, e.g. resonators , specially adapted to MR
• CPC Class Codes: G01R 33/34092 RF coils specially adapted for NMR spectrometers
• CPC Class Codes: G01R 33/3628 Tuning/matching of the transmit/receive coil
• CPC Class Codes: G01R 33/3635 Multi-frequency operation
• CPC Class Codes: G01R 33/3642 Mutual coupling or decoupling of multiple coils, e.g. decoupling of a receive coil from a transmission coil, or intentional coupling of RF coils, e.g. for RF magnetic field amplification
• CPC Class Codes: G01R 33/446 Multifrequency selective RF pulses, e.g. multinuclear acquisition mode spatially selective RF pulses G01R33/4833

Abstract

A dual- or multi-resonant RF/MR transmit and/or receive antenna (1, 2) especially in the form of a planar antenna or a volume array antenna (also called antenna array) is disclosed for MR image generation of at least two different nuclei like e.g. ¹H, ¹⁹F, ³He, ¹³C, ²³Na or other nuclei having different Larmor frequencies. Basically, the antenna is coupled by means of an inductive coupling device (LI) with related transmit/receive channels (T/R). By such an inductive coupling, the tuning and matching of the antenna at the different resonant frequencies is easier to be obtained than in case of a galvanic connection. Further, the invention relates to an MR imaging apparatus comprising such a dual- or multi-resonant RF/MR transmit and/or receive antenna.

Claims

1. Dual- or multi-resonant RF/MR transmit and/or receive antenna, comprising a coil and at least one resonant circuit, which is serially connected into the coil, wherein the antenna is inductively coupled with an RF/MR transmit and/or receive channel by means of an inductive coupling device in the form of at least one loop or coil which is dimensioned and/or positioned in relation to the antenna such that by the resulting magnetic flux between both, resonant frequencies of the antenna are tuned to Larmor frequencies of two or more nuclei of interest and impedance-matched to the connected RF/MR transmit and/or receive channel, wherein the at least one loop or coil is arranged such that it can be mechanically displaced in relation to the antenna for adjusting the magnetic flux between the antenna and the inductive coupling device, whereby the inductive coupling is broadband in that tuning and matching applies to both or all resonant frequencies.

2. RF/MR transmit and/or receive antenna according to claim 1, wherein the inductive coupling device is realized in the form of a first coil which is connected with the RF/MR transmit/receive channel and a second coil which is connected with the antenna, wherein both coils are arranged such that they inductively couple with each other.

6. RF/MR transmit and/or receive antenna according to claim 1, wherein the inductive coupling device is provided by a first coil for inductively coupling the antenna at a first resonant frequency, and a second coil for inductively coupling the antenna at a second resonant frequency.

7. RF/MR transmit and/or receive antenna according to claim 6, wherein a mutual inductive coupling between the first and the second coil is at least partly compensated by overlapping both coils with one another.

8. RF/MR transmit and/or receive antenna according to claim 6, wherein a mutual inductive coupling between the first and the second coil is at least partly compensated by means of a capacitor which is serially connected into both coils.

9. RF/MR transmit and/or receive antenna according to claim 6, wherein a mutual inductive coupling between the first and the second coil is at least partly compensated by means of a transformer having a first winding which is serially connected into the first coil and a second winding which is serially connected into the second coil.

10. RF/MR transmit and/or receive antenna according to claim 6, wherein the first and the second coil is connected by means of a duplexer with a common RF transmission line to the related RF/MR transmit and/or receive channels.

11. RF/MR transmit and/or receive antenna according to claim 2, wherein a drive motor is provided for conducting the displacement of the coil, and wherein the drive motor is driven by means of a drive circuit in dependence on an output signal of a pick up coil or a directional coupler which is loaded by the antenna.

13. RF/MR transmit and/or receive antenna according to claim 1, wherein the antennae is a planar antenna.

14. RF/MR transmit and/or receive antenna according to claim 1, wherein the antenna is a planar array antenna or a volume array antenna.

15. MR imaging apparatus or system comprising an RF/MR transmit and/or receive antenna according to claim 1.

3. RF/MR transmit and/or receive antenna according to claim 3, wherein the first coil is arranged such that it can be displaced in relation to the second coil for adjusting the magnetic flux between both.

4. Dual- or multi-resonant RF/MR transmit and/or receive antenna, comprising a coil and at least one resonant circuit, which is serially connected into the coil, wherein the antenna is inductively coupled with an RF/MR transmit and/or receive channel by means of an inductive coupling device in the form of at least one loop or coil which is dimensioned and/or positioned in relation to the antenna such that by the resulting magnetic flux between both, resonance frequencies of the antenna are tuned to Larmor frequencies of two or more nuclei of interest and impedance-matched to the connected RF/MR transmit and/or receive channel, wherein the at least one loop or coil is arranged such that the magnetic flux between the antenna and the inductive coupling device can be electrically varied, whereby the inductive coupling is broadband it that tuning and matching applies to both or all resonant frequencies.

5. RF/MR transmit and/or receive antenna according to claim 4, wherein the inductive coupling device comprises a coil having a number of windings with one or a plurality of taps which are each connected by means of a diode with one of the terminals of the coil, wherein the diodes are selected such that they can be biased conductive and non conductive by applying a related bias voltage.

12. RF/MR transmit and/or receive antenna according to claim 5, wherein a drive circuit is provided for selecting and switching the diodes conductive and non conductive in dependence on an output signal of a pickup coil or a directional coupler which is loaded by the antenna.