Transmit Array Performance across Subjects at 7 T MRI : Simulations and Experiments

shimming. Right: 10gm average RF absorption or SAR for H(1)-(4) for the same B1+ shimming, and mean B1+ of 2.5uT in the brain. Table 1 shows the stats on B1+ and sample SAR variation across subjects for the same B1+ shimming amplitudes and phases. The homogeneity, SAR ave and peak changes were <10 % across the 4 head models H(1)-(4). Figure 1 The Tx array tuning (Smith Chart) on 3 volunteers (different head shapes and sizes) are shown: The coil tuning per port was robust around 50 Ohms with less than 5% change in the real part of input impedance.