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Abstract

Purpose
Dynamic CEST studies such as dynamic glucose enhanced imaging, have gained a lot of attention recently. The expected CEST effects after injection are rather small in tissue especially at clinical field strengths (0.5–2%). Small movements during the dynamic CEST measurement together with a subtraction-based evaluation can lead to pseudo CEST effects of the same order of magnitude. These artifacts are studied herein.
Methods
A brain tumor patient 3D-CEST baseline scan without glucose injection performed at 3 T is used to generate a virtual dynamic measurement introducing different kinds of simulated motion and B0 shifts.
Results
Minor motion (0.6 mm translations) and B0 artifacts (7 Hz shift) can lead to pseudo effects in the order of 1% in dynamic CEST imaging. Especially around tissue interfaces such as CSF borders or tumor affected areas, the pseudo effect patterns are non-intuitive and can be mistaken as dynamic agent uptake.
Conclusion
Correction or mitigation for small motions is crucial for dynamic CEST imaging, especially in subjects with lesions. Concomitant B0 alterations can as well induce pseudo CEST effects at 3 T.