Inverting <scp>CEST</scp> or R1ρ$$ {R}_{1\uprho} $$ data to generate solute spectra without a priori assumptions

An inversion of the CEST signal is demonstrated that requires minimal assumptions and can qualitatively characterize the distribution of contributing solutes. These results demonstrate proof of concept, but further work is needed to address in vivo conditions, optimize acquisition and analysis methods, and determine trade-offs between sensitivity, accuracy, range of applicability, and prevalence of fitting artifacts. The ultimate ability of the method to characterize the full range of exchanging solutes in vivo is not yet clear.