FIGURE 6.

Fitting of in vivo Z-spectra from gray matter tissue using model 2 at durations of 2 seconds and B_1rms of (A) 0.7, (B) 1.45 and (C) 2.2 μT. Residual errors of fitting are less than 2%. rNOE decreases with increase in B_1rms. Cr-w CEST and CEST@3.5 ppm initially increase and then decrease with B_1rms. CEST@3.5 ppm, CEST contrast at 3.5 ppm; Cr-w CEST, CEST contrast at 1.8 ppm; DS, direct saturation; MT, magnetization transfer; rNOE, relayed nuclear Overhauser effect; σ, average residual error; R², goodness of fit