Magnetic resonance imaging system with a multi-channel impedance matching network

Patent metadata

Field	Value
Publication number	US-9733324-B2
Application number	US-201214130379-A
Country	US
Kind code	B2
Filing date	Jun 21, 2012
Priority date	Jul 4, 2011
Publication date	Aug 15, 2017
Grant date	Aug 15, 2017

Abstract

The Magnetic Resonance Imaging (MRI) system includes a radio-frequency transmitter with multiple transmit channels. The MRI system includes an impedance matching network ( 320, 1402, 1502, 1602 ) for matching the radio-frequency transmitter to a remotely adjustable radio-frequency antenna ( 310, 1504, 1602 ) with multiple antenna elements ( 312, 314, 316, 318, 1404 ). The MRI system includes a processor ( 336 ) for controlling the MRI system. The execution of the instructions by the processor causes it to: measure ( 100, 200 ) a set of radio-frequency properties ( 352 ) of the radio-frequency antenna, calculate ( 102, 202 ) a matching network command ( 354 ) using the set of radio-frequency properties and a radio frequency model ( 366 ), and adjust ( 104, 204 ) the impedance matching network by sending the matching network command to the impedance matching network, thereby enabling automatic remote impedance matching.

First claim

The invention claimed is:

1. A magnetic resonance imaging system for acquiring magnetic resonance data, wherein the magnetic resonance imaging system comprises:
a radio-frequency transmitter for generating radio-frequency pulses during acquisition of the magnetic resonance data, wherein the radio-frequency transmitter has multiple transmit channels;
an impedance matching network adapted for impedance matching the radio-frequency transmitter to a radio-frequency antenna, wherein the radio-frequency antenna comprises multiple antenna elements, wherein the impedance matching network is adjustable remotely, the impedance matching network being circuited between the radio-frequency transmitter and the antenna elements and having a tunable controlled coupling/decoupling network between antenna elements;
a memory for storing machine executable instructions; and
a processor for executing the machine executable instructions, wherein the processor is adapted for controlling the magnetic resonance imaging system, wherein execution of the instructions causes the processor to:
measure a set of radio-frequency properties of the radio-frequency antenna;
calculate a matching network command using the set of radio-frequency properties and a radio frequency model, wherein the radio frequency model is descriptive of the impedance matching network and the radio-frequency antenna; and
adjust the impedance matching network including tuning the coupling/decoupling network between antenna elements by sending the matching network command to the impedance matching network.

2. The magnetic resonance imaging system of claim 1 , wherein the magnetic resonance imaging system further comprises a radio-frequency receiver for acquiring the magnetic resonance data using the radio-frequency antenna, wherein the radio-frequency receiver has multiple receive channels; wherein the radio-frequency transmitter and the radio-frequency receiver are configured for simultaneous transmission on at least one of the multiple transmit channels and simultaneous reception on at least one of the multiple receive channels, and wherein the set of radio-frequency properties comprise in particular an S-Matrix measured using the at least one of the multiple transmit channels and using the at least one of the multiple receive channels.

3. The magnetic resonance imaging system of claim 1 , wherein the radio-frequency properties are at least partially measured using the radio-frequency transmitter.

4. The magnetic resonance imaging system of claim 1 , wherein the magnetic resonance imaging system further comprises a radio-frequency generator, wherein the radio-frequency properties are at least partially measured using the radio-frequency generator.

5. The magnetic resonance imaging system of claim 3 , wherein the magnetic resonance imaging system comprises a set of radio-frequency sensors, wherein the radio-frequency properties are measured at least using the set of radio-frequency sensors.

6. The magnetic resonance imaging system of claim 1 , wherein execution of the instructions causes the processor to acquire a magnetic field map using the magnetic resonance imaging system, wherein the radio-frequency properties are at least partially measured using the magnetic field map.

7. The magnetic resonance imaging system of claim 1 , wherein execution of the instructions further causes the processor to acquire the magnetic resonance data using the magnetic resonance imaging system, wherein the magnetic resonance data is acquired after the impedance matching network has been adjusted.

8. A magnetic resonance imaging system for acquiring magnetic resonance data, wherein the magnetic resonance imaging system comprises:
a radio-frequency transmitter with multiple transmit channels configured to generate radio-frequency pulses during acquisition of the magnetic resonance data;
a radio frequency antenna with multiple antenna elements;
a remotely adjustable impedance matching network configured to impedance match the radio-frequency transmitter to the radio-frequency antenna, the impedance matching network being circuited between the radio-frequency transmitter and the antenna elements and including a tunable controlled coupling/decoupling network disposed between antenna elements;
a memory configured to store machine executable instructions; and
a processor configured to execute machine executable instructions wherein execution of the instructions causes the processor to:
measure a set of radio-frequency properties of the radio-frequency antenna;
determine B1 shim setting for the radio-frequency transmitter using the magnetic resonance imaging system;
calculate a power loss using the set of radio-frequency properties and the B1 shim settings;
choose a matching network adjustment;
transform the set of radio-frequency properties and the B1 shim setting using a radio-frequency model and the matching network adjustment, the radio frequency model being descriptive of the impedance matching network and the radio-frequency antenna;
adjust the impedance matching network including tuning the coupling/decoupling network between antenna elements by sending the matching network command to the impedance matching network;
calculate a changed power loss using the transformed set of radio-frequency properties and the transformed B1 shim setting; and
wherein the matching network command is calculated in accordance with the impedance matching network adjustment if the changed power loss is smaller than the power loss.

9. The magnetic resonance imaging system of claim 8 , wherein execution of the instructions further causes the processor to iteratively repeat the choosing of the matching network adjustment and calculation of the changed power loss.

10. The magnetic resonance imaging system of claim 8 , wherein the impedance matching network is configured to couple at least one pair of the multiple antenna elements, and wherein the coupling between the at least one pair of the multiple antenna elements is remotely adjustable.

11. The magnetic resonance imaging system of claim 10 , wherein the step of calculating the matching network command comprises instructions for adjusting the coupling between the at least one pair of the multiple antenna elements.

12. A non-transitory computer program product comprising machine executable instructions, wherein the machine executable instructions are for execution by a processor controlling a magnetic resonance imaging system for acquiring magnetic resonance data, wherein the magnetic resonance imaging system comprises a radio-frequency transmitter for generating radio-frequency pulses during acquisition of the magnetic resonance data, wherein the radio-frequency transmitter has multiple transmit channels, wherein the magnetic resonance imaging system further comprises an impedance matching network adapted for impedance matching the radio-frequency transmitter to a radio-frequency antenna, wherein the radio-frequency antenna comprises multiple antenna elements, wherein the impedance matching network is adjustable remotely, the impedance matching network being circuited between the radio-frequency transmitter and the antenna elements and having a tunable controlled coupling/decoupling network between antenna elements, wherein execution of the instructions causes the processor to:
measure a set of radio-frequency properties of the radio-frequency antenna;
calculate a matching network command using the set of radio-frequency properties and a radio frequency model, wherein the radio frequency model is descriptive of the impedance matching network and the radio-frequency antenna; and
adjust the impedance matching netw

Assignees

• Findeklee Christian
• Vernickel Peter
• Koninklijke Philips Nv

Inventors

• Findeklee Christian
• Vernickel Peter

Classifications

• G01R33/3628 Primary

  Tuning/matching of the transmit/receive coil · CPC title

• G01R33/3415

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

• G01R33/5659

  caused by a distortion of the RF magnetic field, e.g. spatial inhomogeneities of the RF magnetic field (G01R33/56509, G01R33/56518, G01R33/56536 take precedence) · CPC title

• G01R33/3635

  Multi-frequency operation · 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