Fig. 1.

Assignment of glycogen hydroxyl resonances and demonstration of increased sensitivity in CEST versus conventional MRS. (A and B) ¹H NMR spectra of 200 mM glycogen acquired at 9.4 T in unbuffered H₂O (pH = 7) as a function of ²H₂O concentration at 4°C (A) and as a function of temperature (B). The water frequency was arbitrarily set to 0.0 ppm, as is common for CEST experiments. The OH resonances at 1.2 and 0.7 ppm (2:1 ratio) downfield from water disappear in ²H₂O and broaden at higher temperature. (C) Interestingly, corresponding Z spectra show increased glycogen detectability at higher temperature.