Fig. 4.

Z spectra from a region of interest in a perfused liver at 4.7 T, acquired by using a 200-ms saturation pulse and a B₁ of 3 μT. When adding glucagon to the perfusate, the intensity of the saturated water signal at 1 ppm offset from water (circles) increases ≈150% more during the 130-min perfusion period than the saturated water signal at −1 ppm (triangles). The difference between these two intensities reflects depletion of glycogen.