Abstract:

The concept of B1-shimming is important for improving SNR and uniformity in MRI at high field. B1-shimming can be performed using multiple transmitters connected to a coil array. A homogeneous slice can be achieved by adjusting the magnitude and phase on each transmitter channel until a uniform composite excitation is obtained. In this paper a high resolution I-Q vector modulator has been designed to control the phase and amplitude of eight channels for B1 shimming in MRI at 7T. The IQ modulator replaces more expensive components like digitally controlled phase shifters and attenuators.