Iodine delivery rate of different concentrations of iodine-containing contrast agents with rapid injection

To determine how the concentration of iodinated contrast media for computed tomography studies affects the iodine delivery rate at various conditions. Three nonionic, iodinated contrast agents that are marketed for computed tomography applications were administered through 1.1 and 1.3 mm large peripheral vein catheters into a vein phantom with room temperature and with pre-heating of the agents at 37 degrees C using a power injector. Each injection applied 40 ml of contrast medium at a flow rate of four to eight ml/s. The iodine concentration of Iopromide, Iomeprol, and Iodixanol varied between 300 and 400 mg iodine per cc. The power injector used a pressure limit of 21 bar. For each experiment, the maximum iodine deliver rate was calculated from the highest possible flow rate recorded. Larger vein catheters and the higher contrast temperature yielded the highest flow rates. With the higher iodine concentrations, viscosity limited the injection speed of the achievable pressure limit. The highest iodine delivery rate was 2560 mg/s, using an agent with 320 mg/ml iodine content. With the more concentrated agent, a maximal iodine delivery rate of 2400 mg/s was achieved. Very high iodinated contrast agent concentrations do not increase the iodine delivery rate of rapid peripheral intravenous injections, since the high viscosity of such agents causes the injection pressure to increase more than the higher iodine concentration would compensate for. With lower injection velocities, the higher viscosity of highly concentrated contrast agents may remain without practical consequences.