Dynamic transitions for fast joint determination of CEST-Rex and T1

Motivation: Most CEST techniques are time-consuming and acquire contrast images, which also depend on T1, specific sequence parameters and field inhomogeneities, but not solely on the CEST effect. Goal(s): Direct quantification of the CEST effect and T1 relaxation from a single measurement without separate calibration scans. Approach: A sequence that combines inversion recovery Look-Locker with CEST saturation in continuous measurement in dynamic transitions. The sub-sampled measurements are reconstructed and quantified with a dedicated model-based framework. Results: Good agreement to the reference measurements was found in simulations and phantom measurements, as well as in-vivo measurements. Impact: The proposed method enables faster and more accurate quantification of the CEST effect, due to inherent compensation for B0, T1, and saturation time. Fast quantitative CEST maps provide new insights different from$$$\,T_1\,$$$influenced APTw or$$$\,MTR_{asym}\,$$$measurements and can therefore lead to increased$$$\,$$$specificity.