FIGURE 8.

A, Theoretical signal‐to‐noise ratio (SNR) improvements for indirect detection as a function of flip angle and magnetization used, assuming perfect detection coils and equal levels of polarization for ¹⁵N and ¹³C, where the number of ¹⁵N spins is double the number of ¹³C spins, as is the case when comparing [¹⁵N₂]urea with [1‐¹³C]urea. The upper and lower bounds for the SNR improvement were calculated for the situation when either coil noise (upper bound) or sample noise (lower bound) solely determined $\epsilon$ (Equation 10). B, Calculated and measured SNR improvement for indirect detection as a function of flip angle and magnetization used. The dashed green line is the theoretical SNR improvement with the dual tuned coil used here and the experimentally determined value for $\epsilon$ of 6.07