Lorentzian fitting of Average Rotation of Saturation Effects (AROSE) CEST spectra for quantification in stroke

Motivation: Fitting of CEST spectra is obscured by MT, direct water saturation, and broad fast exchange peaks which result in contamination of quantified signals. Goal(s): Using AROSE spectra for fitting simplifies CEST quantification by reducing the need for isolation of CEST signals due to preemptive filtering. Approach: Fitting was first performed on simulated spectra at different exchange rates and then applied to in vivo data. Results: Our results in MCAO rodents showed that quantification of CEST signal from AROSERRex spectra resulted in low fitting residuals with robust peaks at 3.6, 2.6, and 2 ppm and minimal contamination from MT and fast exchanges. Impact: Fitting using AROSE-CEST spectra improves quantification of CEST exchange by minimizing contributions from broad fast exchanges and other contaminations such as MT which have been challenges for traditional fitting methods such as multiple -pool Lorentzian fitting.