High field magnetic resonance

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 to shim the coil;
• and
• acquiring magnetic resonance data based on a signal received from the coil.

A method for generating a map indicative of a transmit radio frequency (RF) field for each coil in an RF coil array having a plurality of RF coils that forms a part of a magnetic resonance imaging (MRI) system, the steps of the method comprising:

• a) directing the MRI system to, for each coil in the RF coil array, operate at least one of the plurality of coils in the RF coil array to generate a transmit RF field and obtain a relative measurement of an RF transmission (B1+) map for a given coil in the RF coil array by varying at least one of a magnitude value or a phase value of an RF waveform provided to the given coil in the RF coil array, wherein the relative measurement of the B1+ map for the given coil indicates relative contributions of the given coil to the RF coil array;
• b) directing the MRI system to operate the plurality of coils of the RF coil array to generate another transmit RF field and obtain an absolute measurement of the B1+ map for the RF coil array, wherein the absolute measurement of the B1+ map for the RF coil array indicates contributions of all the plurality of coils in the RF coil array when transmitting together;
• c) computing a global B1+ map for at least the plurality of coils of the RF coil array from the absolute measurement;
• and
• d) producing a B1+ map for each coil in the RF coil array by weighting the global B1+ map using a relative phase computed from the relative measurement obtained for that coil, wherein each B1+ map comprises pixels describing a distribution of a complex valued B1+ field generated in space by the coil;
• wherein the relative phase is computed for each coil as a signal ratio by dividing magnetic resonance signals in the relative measurement obtained by the coil in step a) by reference magnetic resonance signals.