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. Author manuscript; available in PMC: 2011 Aug 1.
Published in final edited form as: J Magn Reson. 2010 May 10;205(2):235–241. doi: 10.1016/j.jmr.2010.05.004

Fig. 5.

Fig. 5

Simulation of CEST contrast of five saturation transfer sites, being at 3.65, 2.3, 1.2, −3 and −3.5 ppm. The concentration of each site was assumed to be 1:1000, 1:1000, 1:500, 1:500 and 1:500, with their exchange rates being 50, 50, 50, 10 and 10 s−1, respectively. a) The simulated Z-spectra and direct RF saturation effect for RF amplitude of 1 and 2 μT was shown in dotted and dash dotted line, respectively. b) The CEST contrast wa obtained by subtracting Z-spectra from RF spillover effects for two RF amplitudes. The frequency resolution of CEST contrast degraded with RF amplitude due to direct RF saturation effect and the coupling among CEST contrasts. c) The RF amplitude-dependent MTRasym may be significantly lower than the CEST contrast due to a negative shift attributable to NOE effects.