1Department of Radiology, Bernard and Irene Schwartz Center for Biomedical Imaging, New York University, New York, NY, United States; 2Sackler Institute of Graduate Biomedical Sciences, New York University School of Medicine, New York, NY, United States; 3Department of Radiology, Bernard and Irene Schwartz Center for Biomedical Imaging, New York University School of Medicine, New York, NY, United States
Given the constraints imposed by the hardware resource in terms of RF power delivery and reflection handling capabilities, any practical RF pulse used on an MR scanner must be designed with those capabilities on mind. In parallel transmission, coupling and interaction taking place in the multi-port structure as well as in the subject can significantly affect individual channel RF power transmission and the demands placed upon the power amplifiers. By using pre-scan based multi-channel calibration, we designed parallel RF excitation pulses obeying the forward / reflected peak and average power limits of the RF power amplifier. Additionally, global SAR limits were incorporated in the RF pulse design. Results showed that the prediction capability of this new calibration method enables the design of parallel RF excitation pulses respecting strict and multifaceted power limits.