The Bolus Effect in Excretory Uroqraphy

The authors suggest that the quality of an excretory urogram is related to the concentration of contrast material in the urine but is more dependent on the amount of contrast material excreted. The amount excreted increases with increasing doses, whereas the concentration shows considerable variability. Following rapid injection, the peak plasma concentration of contrast material produces a peak filtered load which acts as a contrast bolus passing through the kidney. This bolus produces tubular and pelvicalyceal dilatation corresponding to the optimal nephrogram during the first five minutes and the optimal urogram during the first ten to fifteen minutes.