FIG. 5.

Experimental MTR_asym, APT*, MTR_double,vdc, AREX, MTR_double,vdc, and AREX_double,vdc of creatine phantoms as a function of measured (T₁, T₂) (a) and fitted f_sk_sw (b). f_s and k_sw in (a) were relatively constant, with fitted values of (0.0015, 0.0014, 0.0015) and (59, 50, 46 s⁻¹), respectively, for the three phantoms with varying MnCl₂ concentrations. In (b), f_sk_sw values were (0.0217, 0.0347, 0.0689, 0.0921, 0.1109 s⁻¹) for five phantoms with varying pH and creatine concentration. Detailed parameters are listed in Table 1. Only AREX and AREX_double,vdc show the desired linearity and f_s and k_sw while being independent of T₁ and T₂. However, only AREX_double,vdc avoids contamination by rNOE effects in egg white (c) and amine contributions in glutamate (d), cases where AREX is non-specific similar to conventional MTR_asym (which is also plotted in (c) and (d) for comparison)