NUMERICAL-SIMULATION OF SAR AND B-1-FIELD INHOMOGENEITY OF SHIELDED RF COILS LOADED WITH THE HUMAN HEAD

The finite-difference time-domain (FDTD) method is combined with the m ethod of moments (MoM) to compute the electromagnetic fields of shield ed radio frequency (RF) coils loaded with an anatomically accurate mod el of a human head for high-frequency magnetic resonance imaging (MRI) applications. The combined method can predict both the specific energ y absorption rate (SAR) and the magnetic field (known as the B-1 field ) excited by any RF coils. Results for SAR and B-1 field distribution, excited by shielded and end-capped birdcage coils, are calculated at 64, 128, 171, and 256 MHz, The results show that the value of SAR incr eases when the frequency of the B-1 field increases and the B-1 field exhibits a strong inhomogeneity at high frequencies.