Rf coil elements with split dc loops for magnetic resonance imaging systems for integrated parallel reception, excitation, and shimming and related methods and devices

Patent metadata

Field	Value
Publication number	US-2016116556-A1
Application number	US-201514881767-A
Country	US
Kind code	A1
Filing date	Oct 13, 2015
Priority date	Oct 22, 2014
Publication date	Apr 28, 2016
Grant date	—

Abstract

Systems, methods and devices are configured for integrated parallel reception, excitation, and shimming (iPRES) with RF coil elements with split DC loops. Parallel transmit/receive (which can include B 1 shimming and/or parallel imaging capabilities) and B 0 shimming employ the same set of localized coils or transverse electromagnetic (TEM) coil elements, with each coil or TEM element working in both an RF mode (for transmit/receive and B 1 shimming) and a direct current (DC) mode (for B 0 shimming) simultaneously. Both an RF and a DC current (in split DC loops) can flow in the same coil element simultaneously but independently with no electromagnetic interference between the two modes.

First claim

1 . A Magnetic Resonance Imaging (MRI) system, comprising:
an RF coil array with a plurality of coil elements, wherein at least some of the coil elements include a plurality of separate direct current (DC) loops for circulating DC current, and wherein the RF coil array is configured to be simultaneously operative in both (i) an RF mode for at least one of transmit or receive and (ii) a DC mode with DC current flow in respective separate DC loops of the at least some coil elements to generate local B 0 magnetic fields for B 0 shimming; at least one DC power supply in communication with the RF coil array to supply DC current to the DC loops of the at least some coil elements; and a circuit in communication with the RF coil array configured to direct the at least one DC power supply to provide DC current to the separate DC loops of the at least some coil elements to generate the local B 0 magnetic fields for B 0 shimming.

2 . The system of claim 1 , wherein the separate DC loops for the at least some respective coil elements includes a first DC loop and a second DC loop, wherein the first DC loop and the second DC loop are configured with switches to selectively define additional separate DC loops that are smaller DC loops than the first and second DC loops.

3 . The system of claim 2 , wherein the switches each comprise at least one FET.

4 . The system of claim 2 , wherein the at least one DC power supply comprises first and second power supplies, the first power supply providing DC current to the first DC loop and the second DC power supply providing DC current to the second DC loop, and wherein the first and second power supplies are independently adjustable to provide different DC current amounts to respective first and second DC loops.

5 . The system of claim 4 , wherein respective coil elements include an RF conductor that defines an RF path, and wherein the coil elements with the separate DC loops comprise a plurality of spaced apart capacitors electrically connected to the RF conductor, at least one residing between terminal inputs for the first power supply for the first DC loop and at least one residing between terminal inputs for the second power supply for the second DC loop.

6 . The system of claim 5 , wherein the coil elements with the separate DC loops comprise at least one capacitor that resides between the terminal inputs of the first power supply and at least one capacitor that reside between the terminal inputs of the second power supply.

7 . The system of claim 1 , wherein respective coil elements include a conductor defining an RF path, and wherein the coil elements with the separate DC loops are configured to independently circulate DC current in each separate DC loop, and wherein the separate DC loops each comprise at least two separate inductors, at least one inductor of each separate DC loop associated with a respective at least one parallel inductor capacitor (LC) resonant circuit with a high resonant frequency, wherein DC current flows through the at least two inductors in each of the separate DC loops.

8 . The system of claim 1 , wherein respective coil elements include a conductor defining an RF path with a perimeter, wherein the separate DC loops of the coil elements having the separate DC loops include conductor segments of the conductor defining the perimeter of the RF path, and wherein the separate DC loops each have a respective perimeter that is smaller than the RF path perimeter with at least part of the separate DC loops each residing inside a boundary of the perimeter of the RF path of the conductor.

9 . The system of claim 1 , wherein the separate DC loops comprise between 2-12 separate DC loops for a respective coil element, and wherein the separate DC loops each have a respective perimeter that is smaller than a conductor RF path perimeter of a corresponding coil element, with at least part of the separate DC loops each residing inside a boundary of the perimeter of the RF path of the conductor.

10 . The system of claim 1 , wherein the RF coil array is (i) a receive-only RF coil array, (ii) a transmit-only RF coil array, or (iii) a transmit and receive RF coil array, and wherein, when DC current flows through spaced apart inductors of parallel inductor capacitor (LC) resonant circuits of respective DC loops having a high resonant frequency, RF signal travels across a corresponding capacitor of the respective LC resonant circuits.

11 . The system of claim 1 , wherein the RF coil array is configured as a cooperating set of a transmit only and a receive only RF coil array, and wherein, only the receive only RF coil array has the DC mode with DC current flow in the separate DC loops of respective coil elements for B 0 shimming.

12 . The system of claim 1 , wherein the circuit is configured to control the at least one power supply to individually adjust amperage and/or direction of DC current flow in the separate DC loops of corresponding coil elements.

13 . The system of claim 1 , wherein the coil elements of the RF coil array with the separate DC loops each have a multiple-tuned RF circuit with concurrent high and low resonant frequencies.

14 . The system of claim 1 , wherein the circuit is in communication with or partially or totally onboard an MR Scanner, and wherein at least a majority of the coil elements comprise the separate DC current loops, and wherein the separate DC current loops each include at least one inductor from at least one parallel inductor capacitor (LC) resonant circuit with a high resonant frequency corresponding to an operating frequency of the MR Scanner.

15 . The system of claim 14 , wherein, in transmit operation, DC current flows through the inductor of the LC resonant circuit of each separate DC loop while RF current flows across the capacitor of the LC resonant circuit.

16 . The system of claim 1 , further comprising an MR Scanner in communication with the RF coil array and a transmit/receive switch in communication with the MR Scanner and the RF coil array.

17 . The system of claim 1 , wherein the circuit is in communication with or partially or totally onboard an MR Scanner.

18 . The system of claim 1 , wherein the circuit is configured to generate B 0 maps associated with the generated local B 0 magnetic fields and perform B 0 shimming.

19 . The system of claim 1 , wherein the RF coil array is configured to generate the local B 0 magnetic fields to provide a uniform magnetic field across biological tissue or target material.

20 . A method of shimming Magnetic Resonance (MR) systems, comprising:
providing at least one RF coil with a plurality of coil elements with each of the plurality of coil elements having at least two separate direct current (DC) current loops; operating the at least one RF coil in at least one of an RF transmit or receive mode; flowing DC current through the separate DC current loops of each respective coil element concurrently with the transmit or receive mode; and generating local B 0 magnetic fields in response to the flow of the DC current through the DC current loops, thereby B 0 shimming an imaging space of a magnet of the MR system using the generated local B 0 magnetic fields.

21 - 28 . (canceled)

29 . An RF coil assembly for a Magnetic Resonance Imaging (MRI) system, comprising:
at least one RF coil array with a plurality of RF coil elements, wherein each coil elements include an RF conductor defining an RF path with a perimeter, wherein at least some of

Assignees

• Univ Duke

Inventors

• Darnell Dean
• Truong Trong-Kha
• Song Allen W

Classifications

• 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

• G01R33/3415

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

• G01R33/3875 Primary

  using correction coil assemblies, e.g. active shimming · CPC title

• G01R33/36

  Electrical details, e.g. matching or coupling of the coil to the receiver · CPC title

• G01R33/34092

  RF coils specially adapted for NMR spectrometers · CPC title