A reassessment of quasi-steady-state enhanced T1 normalization in quantitative CEST analysis

Motivation: Correction of T1 contribution in quantitative CEST MRI often assumes an equilibrium CEST signal. However, most CEST scans were not and will unlikely to be performed under equilibrium conditions. Goal(s): To investigate T1 correction and improve CEST quantification using CEST scans under practical scan (non-equilibrium) protocols. Approach: We performed numerical simulation and in vivo experiments to evaluate T1 correction without and with quasi-steady-state analysis. Results: Our study demonstrated that QUASS postprocessing enhances the accuracy of T1 correction with the AREX metric independent of the RF saturation time, relaxation delay, and T1. Impact: Our study provides a practical qCEST solution that lays the foundation for future clinical translation to improve the quantification and specificity of CEST imaging.