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Abstract #3990

Glycogen Chemical Exchange Effects in 1H-MRS and Glyco-CEST at 3T and 7T

Ronald Ouwerkerk1, Yee Kai Tee2, Craig K. Jones3, 4

1Biomedical and Metabolic Imaging Branch, NIH/NIDDK, Bethesda, MD, United States; 2Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford, United Kingdom; 3F.M. Kirby Research Center for Functional Brain Imaging , Kennedy Krieger Institute, Baltimore, MD, United States; 4Division of MR Research, The Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, United States

Glycogen can be measured in vivo with localized 1H-MRS or glycoCEST imaging. The chemical exchange between water and glycogen makes glycoCEST possible, but could lead to errors in water-suppressed 1H-MRS. We used glycoCEST and water-suppressed 1H-MRS on glycogen phantoms in physiological buffers to investigate this error source. The CEST effect was limited to the downfield H1 proton of glycogen. Varying water-suppression RF power level showed saturation transfer H1, but not on the upfield glycogen protons. The glycoCEST water reduction correlated with the concentrations estimated with 1H-MRS on the upfield peaks. Thus, both methods could be used to study glycogen metabolism.