Determination of the Larmor Frequency for Highest Transmit Efficiency in the Head

MRI scanners with higher B0 fields typically provide a stronger Signal to Noise Ratio (SNR) which results in MRI images with their resolution or shorter acquisition time [1]. Stronger B0 fields require higher operating frequencies of the B1 field, and the shorter wavelengths cause in homogeneities in the B1 field distribution due to scattering and interference in the tissues. At higher B0 RF fields are limited to not cause excessive absorption of power in the tissues. Specifically, electric fields induce currents in conductive tissues causing heat dissipation which raise local temperature potentially leading to patient discomfort and even tissue damage. Hence, local Specific Absorprtion Rate (SAR) and temperature are limited.