Fig. 11.

Ideal surface current patterns associated with the best possible SNR at a voxel position intermediate between the center and the surface of a sphere are compared, at 7 T, with SNR-optimized current patterns for different coil configurations. Current patterns are shown for two time points separated by Δωt = π/2. The corresponding SNR values, normalized to the ultimate intrinsic SNR, are reported in the left-hand column. The performance with respect to the ultimate intrinsic SNR of the same array configurations at 7 T is reported in parentheses. The radius of the single loop coil is equal to 24.6 mm, i.e. the distance between the coil center and the voxel of interest, divided by square root of five. The radius of the other coil configurations was chosen empirically to be 35.7 mm, in order to resemble the shape of the ideal current patterns.