Abstract
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. 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. 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. 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.
Highlights
Since it was first demonstrated by Wolff and Balaban in 1990 [1], chemical exchange saturation transfer (CEST) has emerged as an alternative MRI contrast [2,3,4,5]
Among numerous key biomolecules which can be indirectly detected via their chemical exchange with water, D-glucose or its analogues in particular has recently shown potential as a new contrast agent with CEST [6,7], chemical exchange sensitive spin lock (CESL) [8,9,10,11] or chemical exchange based T2 relaxation enhancement [12]
Even 1–2% of artifactual signal due to motion can hamper the sensitivity of intrinsic signal changes as it has been widely reported in other modalities including functional brain MRI
Summary
Since it was first demonstrated by Wolff and Balaban in 1990 [1], chemical exchange saturation transfer (CEST) has emerged as an alternative MRI contrast [2,3,4,5]. Dynamic CEST and CESL of glucose (glucoCEST/glucoCESL) have been performed to study tumor models in animals [6,13] and patients with glioblastoma [10,14] as it monitors the uptake and wash-out of glucose. Enhanced (DGE) contrast [7,9,13,14] is assumed to mostly reflect the CEST effect of the glucose injection. Even 1–2% of artifactual signal due to motion can hamper the sensitivity of intrinsic signal changes as it has been widely reported in other modalities including functional brain MRI (fMRI). As motion correction and co-registration are mandatory steps in fMRI postprocessing, similar attempts have been recently made in glucoCEST/glucoCESL studies, which observed erroneous signal due to severe patient’s movement [10,14]. Use of immobilization devices was reported to reduce patient’s motion [15], but this option may not be globally available due to a patient’s discomfort level and may conflict with local ethics
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
