Decoupling of parallel transmission arrays in magnetic resonance imaging

A method of configuring a parallel transmission magnetic resonance imaging (MRI) system with a decoupling system for an array of coils of the parallel transmission MRI system, the method comprising:

• obtaining impedance matrix data for the array of coils without the decoupling system;
• determining, based on the impedance matrix data for the array of coils, a cost function representative of deviation from a decoupled operating condition for the array of coils in which the coils are decoupled via the decoupling system, wherein the objective function comprises a least squares cost function based on a difference between the decoupling matrix and a target impedance matrix representative of the array of coils in the decoupled operating condition;
• using an iterative, non-linear optimization solver to determine a decoupling matrix that minimizes the objective function, wherein the decoupling matrix specifies a set of impedances of the decoupling system;
• configuring the decoupling system to the array of coils based on the optimized elements of the decoupling matrix such that, when in use, the parallel transmission MRI system reduces or eliminates the transmission of power from one channel to other channels of the MRI system and provides an improved power efficiency when obtaining image data using the MRI system;
• and
• storing the image data in a non-volatile computer readable medium from which the image data can be output to a display.

A magnetic resonance imaging (MRI) system comprising:

• a plurality of transmitters to generate a parallel transmission radio frequency (RF) pulse;
• an array of coils coupled to the plurality of transmitters to apply the parallel transmission RF pulse to a subject;
• and
• a decoupling system connected to the plurality of transmitters and the array of coils and configured in accordance with a decoupling matrix to attain a decoupled operating condition for the array of coils;
• wherein each element of the decoupling matrix is representative of an impedance between a respective pair of nodes, each node being associated with either a respective one of the transmitters or a respective one of the coils;
• wherein the elements of the decoupling matrix are optimized using a non-linear optimization solver to minimize a least squares cost function based on impedance matrix data for the array of coils without the decoupling system, the least squares cost function being based on a difference between the decoupling matrix and a target impedance matrix representative of the array of coils in the decoupled operating condition, and
• wherein operation of the MRI system using the decoupling matrix reduces or eliminates the transmission of power from one channel to other channels of the MRI system and provides an improved power efficiency.