Comparison of the normalizations MTRasym (left column) and MTRRex (right column) for B1 = 0.2, 1.0, 1.4 and 2.0 µT. In each case, the estimation of the chemical exchange saturation transfer (CEST) effect is higher for MTRRex. The phantoms with varying agar concentration (0, A1–A5) show similar contrast in MTRRex, whereas MTRasym shows diluted contrast with increasing agar concentration. Differences in pH and creatine concentration are reflected in both magnetization transfer ratios (MTRs). Therefore, MTRRex has all the properties of a spillover correction.