Optimum iodine concentration of contrast material through microcatheters: hydrodynamic analysis of experimental results.

It is important to increase the iodine delivery rate (I), that is the iodine concentration of the contrast material (C) x the flow rate of the contrast material (Q), through a catheter to obtain high quality arteriograms. The iodine delivery rate varies depending on the iodine concentration of the contrast material. The purpose of this study is to estimate the optimum iodine concentration (Copt) of contrast material (i.e. the iodine concentration at which I becomes maximum) through a microcatheter of a given length (L), inner diameter (D) and injection pressure (P). Iohexol, ioversol and iopamidol of 11-12 iodine concentrations (140-350, 160-350 or 160-370 mg cm(-3)) at 37 degrees C are used. I and Reynolds number (Re) of the flow of each contrast material through four microcatheters (0.49-0.68 mm in inner diameter, 1000-1500 mm in length) at injection pressures of 1.38, 2.76, 4.14 and 5.52 x 10(6) Pa (200, 400, 600 and 800 pounds per square inch) are obtained experimentally. The relationships between I and C and between I and Re are examined for each catheter and injection pressure. Copt is 160-280 mg cm(-3) for iohexol, 180-280 mg cm(-3) for ioversol and 200-300 mg cm(-3) for iopamidol. I becomes maximum when Re approximates the critical Reynolds number (Re approximately 2300). Utilizing this principle, we can estimate Copt and its flow rate through a microcatheter of a given L, D and P.