Water saturation shift referencing (WASSR)  buy Y-27632 is one of the most commonly used techniques to
correct for this shift; however, the method requires extra scans possibly before and after the CEST imaging. Using a model-based approach eliminates the additional scan(s) required because the shift can be determined directly from the collected spectrum as part of the model fitting . Performing model-based quantitative analysis of the CEST effect for CW-CEST is simple and is generally achieved using the analytical solution to the Bloch–McConnell equations. However, CW-CEST is not feasible in clinical applications due to specific absorption rate (SAR) and hardware limitations, making pulsed-CEST the only viable irradiation scheme for clinical translation currently. Apitolisib clinical trial Finding the proton MR behavior in response to time varying RF power as present in the pulsed-CEST scheme for model-based analysis is time consuming because the solution to the Bloch–McConnell equations must be arrived at either using a numerical differential equation solver or discretizing the pulses into a series of short continuous RF segments. In the latter case, referred to here as the discretization method, the individual segments are solved using the simple analytical solution
for CW-CEST with the magnetization being propagated through each of the segments, the final values from one segment serving as the initial conditions for the next one  and . Due to the combination of the repeated calculations required in the discretization method and the multiple iterations within the optimization used for model-based strategy, the analysis of pulsed-CEST is often much slower than its continuous counterpart. Hence, pulsed-CEST is often treated as CW-CEST by finding the equivalent
average field (AF)  and  or power (AP)  of the pulse train to perform the analysis using the faster solution to the Bloch–McConnell equations under continuous saturation. isothipendyl Recently, studies have shown that a continuous approximation (both AF and AP) produces narrower off-resonance excitations when compared with pulsed saturation  and that the CESTR is different for pulsed-CEST and CW-CEST when the exchange rate is more than 50 s−1. These raise the issue whether pulsed-CEST can be analyzed via the equivalent CW-CEST or a discretization method must be used. In this study, the differences in the z-spectra from a pulsed-CEST experiment and the equivalent continuous (AF and AP) approximation are examined using simulations to determine the validity of the latter for the analysis of pulsed-CEST data. Additionally, model-based quantitative analysis of pulsed-CEST data from a tissue-like phantom using the continuous approximation and discretization methods are compared.