RF shimming with implant safety control in MRI transmit arrays through second-order cone programming

Inside a Magnetic Resonance Imaging (MRI) birdcage, the patient is subjected to the static magnetic field B0 generated by a magnet, and the radiofrequency (RF) magnetic field B1, usually generated by a transmit array. A common technique used in MRI to achieve a higher image quality is RF shimming. It aims to maximize the homogeneity of the B1 field over the desired region by properly adjusting the driving excitations of channels in the MRI transmit array. Several strategies have been followed to achieve this objective. One of the most successful ones is minimizing the mean square error (MSE) of the magnitude of the B1 field with respect to a reference value.