Figure 3.

The experimentally measured and numerically calculated $\mid {\mathrm{B}}_1^{+}\mid$ and $\mid {\mathrm{B}}_1^{-}\mid$ fields with and without the HDC pads in sagittal and axial views. For comparison purposes the experimental $\mid {\mathrm{B}}_1^{+}\mid$ maps are normalized with the transmission voltage while the $\mid {\mathrm{B}}_1^{-}\mid$ maps are normalized by the standard deviation of the “noise scan”. The calculated $\mid {\mathrm{B}}_1^{+}\mid$ and $\mid {\mathrm{B}}_1^{-}\mid$ maps are normalized by the input current in the conductor elements in the coil model. To correlate the $\mid {\mathrm{B}}_1^{-}\mid$ enhancement with SNR in the corresponding region in Fig. 4, an ROI is selected in the spinal cord region. The average $\mid {\mathrm{B}}_1^{-}\mid$ enhancement in the ROI is 29±5% (Mean ± SD).