SAR Comparison for "Head First" and "Feet First" Patient Loading at 3T MRI with Numerical Simulations

Xin Chen¹, Yong Wu², Zhen Yao², Michael Steckner¹, Robert Brown²

Numerical simulations of SAR have been widely used to investigate MRI RF safety. Although studies have covered multiple human models , imaging landmarks , and transmit body coil types , more clinical imaging scenarios remain to be investigated, such as patient scanned as head first or feet first. Eddy current induced in conductive imaging subject by RF magnetic field is asymmetric even with a perfectly symmetric phantom and coil. Human tissue heterogeneity and asymmetry add even more complexity to this phenomenon. In this work, we used FDTD numerical simulations to study a generic body transmit coil loaded with a digital human model. Simulations were performed for 11 imaging landmarks from head to toe, both head first and feet first. Significant differences in peak local SAR were observed for two loading directions.