High field magnetic resonance

Abstract

A magnetic resonance system is disclosed. The system includes a transceiver having a multichannel receiver and a multichannel transmitter, where each channel of the transmitter is configured for independent selection of frequency, phase, time, space, and magnitude, and each channel of the receiver is configured for independent selection of space, time, frequency, phase and gain. The system also includes a magnetic resonance coil having a plurality of current elements, with each element coupled in one to one relation with a channel of the receiver and a channel of the transmitter. The system further includes a processor coupled to the transceiver, such that the processor is configured to execute instructions to control a current in each element and to perform a non-linear algorithm to shim the coil.

What is claimed is: 
     
       1. A system comprising:
 a transceiver having a multichannel receiver and a multichannel transmitter wherein each channel of the transmitter is configured for independent selection of at least one of frequency, phase, time, space, and magnitude and each channel of the receiver is configured for independent selection of at least one of space, time, frequency, phase and gain; 
 a magnetic resonance coil having a plurality of current elements, each element coupled in one to one relation with a channel of the receiver and a channel of the transmitter; and 
 a processor coupled to the transceiver, wherein the processor is configured to execute instructions to control a current in each element and to perform a non-linear algorithm that implements a non-linear relationship between flip angle and magnetic resonance signal intensity to shim the coil, and wherein the non-linear algorithm uses a penalty function that returns a value describing at least a phase and a magnitude for each current element of the magnetic resonance coil. 
 
     
     
       2. The system of  claim 1  wherein the coil includes at least one of a transverse electromagnetic volume coil and a transverse electromagnetic surface coil. 
     
     
       3. The system of  claim 1  wherein the processor executes instructions to perform dynamic RF field control of the coil. 
     
     
       4. The system of  claim 1  further including a user input console coupled to the processor. 
     
     
       5. The system of  claim 4  wherein the user input console is configured to receive a user selection for RF field optimization. 
     
     
       6. The system of  claim 1  wherein the coil is configured for use with a coil magnetic field having a magnetic field strength of at least 3T. 
     
     
       7. A method comprising:
 receiving a user selected criteria for optimization; 
 executing instructions using a processor to configure a multichannel transmitter and a multichannel receiver based on the criteria, the transmitter and the receiver each coupled to a multichannel coil wherein each channel of the coil includes a current element and each channel of the coil is coupled in one to one relation with a channel of the transmitter and a channel of the receiver; 
 executing instructions using a processor to perform a non-linear algorithm that implements a non-linear relationship between flip angle and magnetic resonance signal intensity to shim the coil, and wherein the non-linear algorithm uses a penalty function that returns a value describing at least a phase and a magnitude each current element of the multichannel coil; and 
 acquiring magnetic resonance data based on a signal received from the coil. 
 
     
     
       8. The method of  claim 7  wherein executing instructions includes performing an iterative algorithm. 
     
     
       9. The method of  claim 7  wherein executing instructions includes configuring the coil for predetermined homogeneity within a particular region of the coil. 
     
     
       10. The method of  claim 7  wherein executing instructions includes controlling a current in a transmission line as to at least one of magnitude, phase, frequency, space and time. 
     
     
       11. A system comprising:
 a radio frequency (RF) transmit coil having a plurality of current elements;   a multichannel transmitter having a plurality of transmit channels, each of the plurality of transmit channels coupling to at least one of the plurality of current elements in the RF transmit coil and being configured for independent selection of at least one of frequency, phase, magnitude, and time; and   a processor coupled to the multichannel transmitter, wherein the processor is configured to execute instructions to control a current in each element and to perform a non-linear algorithm that implements a non-linear relationship between flip angle and magnetic resonance signal intensity to shim the RF transmit coil, and wherein the non-linear algorithm uses a penalty function that returns a value describing at least a phase and a magnitude for each current element in the RF transmit coil.   
     
     
       12. The system as recited in claim 11 further comprising:
 a receiver having at least one receive channel configured for independent selection of at least one of frequency, phase, magnitude, and time; and   an RF receive coil having at least one current element, the at least one current element being coupled to at least one of the receive channels.   
     
     
       13. The system as recited in claim 12 in which the RF receive coil includes at least two current elements, each of the at least two current elements being coupled to at least one of the receive channels. 
     
     
       14. The system as recited in claim 12 in which the at least one receive channel comprises at least two receive channels. 
     
     
       15. The system as recited in claim 11 in which one of the plurality of transmit channels is coupled to more than one of the plurality of current elements in the RF transmit coil. 
     
     
       16. The system as recited in claim 11 in which one of the plurality of current elements in the RF transmit coil is coupled to more than one of the plurality of transmit channels. 
     
     
       17. The system as recited in claim 11 in which the multichannel transmitter is further configured for dynamic spatial adjustment of the plurality of current elements. 
     
     
       18. The system as recited in claim 11 in which the RF transmit coil includes a transverse electromagnetic coil element. 
     
     
       19. The system as recited in claim 11 in which the processor executes instructions to perform dynamic RF field control of the RF transmit coil. 
     
     
       20. The system as recited in claim 11 in which the plurality of current elements in the RF transmit coil are configured such that neighboring current elements are decoupled relative to each other. 
     
     
       21. The system as recited in claim 20 in which the plurality of current elements are geometrically decoupled by orienting dipoles of the current elements for phase cancellation. 
     
     
       22. The system as recited in claim 20 in which the plurality of current elements are geometrically decoupled by increasing a distance between current elements until mutual inductance is reduced below a threshold value. 
     
     
       23. The system as recited in claim 20 in which the plurality of current elements comprises at least one of a plurality of transverse electromagnetic (TEM) coil elements and a plurality of loop coil elements. 
     
     
       24. The system as recited in claim 20 in which neighboring current elements are decoupled using at least one of reactive decoupling and capacitive decoupling. 
     
     
       25. The system as recited in claim 11 further comprising a tune and match network that includes at least one of a phase shifter and a phased line with diode protection. 
     
     
       26. The system as recited in claim 12 wherein the receiver is a digital receiver.