[A short infusion or a bolus injection of contrast medium in i.v. urography. Comparative density measurements in the kidney pelvic-caliceal system using sequential computed tomography].

The rate of contrast injection during i.v. urography may vary considerably (bolus injection or drip infusion). The effect of 5 rates of injection (6, 12, 18, 36 and 72 ml/min) on the contrast density in the renal collecting system was examined over a period of 30 minutes. Measurements showed an inter-individual difference of more than 200% in each group. The intra-individual variations for different rates of injection were very slight; individual concentration in the kidney for a given dose depends only slightly on the rate of injection. There is no statistically significant improvement in contrast values as a result of a bolus injection. The reduced incidence of side effects justifies the use of bolus injections but pressure injections are unnecessary from a diagnostic point view.