Fig. 2

(a) Chemical structure of iopamidol highlighting the amide groups resonating at 4.3 and 5.5 ppm; (b) MTRasym of iopamidol for a series of pH values with saturation frequency (B1) of 3.6 µT; (c) STratio vs pH calibration curve with third order polynomial fitting; (d) calculated pH maps in phantoms using the third order calibration curve.