Here you find analytic solutions of the Bloch-McConnell equations describing Z-spectra. This R1ρ-model is based on the article Zaiss et al. A combined analytical solution for chemical exchange saturation transfer and semi-solid magnetization transfer, (2014), NMR Biomed. doi: 10.1002/nbm.3237.
It is a very lean code to give you a tool illustrating the principal behaviour of a CEST effect and its interaction with the direct water saturation. It is actually the same source code as for the Solution for 2-pools under cw irradiation. Just the BATCh file is adjusted.
Dowload zipped Matlab implementations here or find the package on github.com/cest-sources/Z-cw
For the 3-pool-simulation the 2-pool code must only be extended by the following fields in the struct P.
% % semi-solid MT pool 'c' P.fC=0.139; % proton fraction of the semi-solid pool (WM-like) P.kCA=23; % exchange rate [s^-1] P.dwC=-2; % deltaW_B in [ppm} (chemical shift) P.R2C=1/(9.1*10^-6); % transversal relaxation rate 1/T2 of pool c [s^-1] P.R1C=1; % longitudinal relaxation rate 1/T1 of pool c [s^-1] P.MT_lineshape='Lorentzian'; % semi-solid Lineshape
To see the full width of the MT the frequency axis must be extended.
% sequence parameters P.xZspec= [-150:0.1:150]; % ppm
Now the function Z_cw(P) is called and plotted.
figure(32), plot(P.xZspec,Z_cw(P),'r-') ; hold on;