Contrast enhancement pharmacokinetics of six ionic and nonionic contrast media.

The contrast enhancement of six contrast media (CM) was compared in 13 tissues of the rat after rapid intravenous bolus injection. The rats were sacrificed at 0 and 40 seconds and 2, 5, and 15 minutes after contrast injection. 125I labeled diatrizoate, metrizamide, ioxaglate, iohexol, iopamidol, and a nonionic dimer, iodecol, were each injected at a dose of 612 mg iodine per kg body weight, and iodine concentration (IC) and contrast enhancement were calculated from radioactivity measurements. Higher blood IC values were obtained with the nonionic CM; similar enhancement patterns were seen in the spleen, heart, lungs, and brain. Renal IC was directly related to the number of iodine atoms per ion or molecule of CM. In consequence, renal IC was inversely related to the CM osmolality, but no such correlation was seen with the blood IC. Metrizamide produced the greatest IC in the organs of the gastrointestinal tract. There was no apparent correlation of IC with molecular structure of physicochemical parameters of the CM in any of the other tissues studied.