DETERMINATION OF TRANSPORTED URETERIC VOLUME IN DOGS BY CINEROENTGENOLOGIC ANALYSIS

¹ From the Department of Radiology, The University of Rochester Medical Center, Rochester, New York

The kidney pelves of 4 mongrel dogs were infused with contrast media at known constant rates through nephrostomy tubes. Cine studies were carried out as boluses formed at the ureteral cone. From these studies, the average length, average area, and average "volume" of the boluses were determined for various flow rates. Each was multiplied by the observed peristaltic frequency to produce length, area, and volume factors. Urinary excretion was determined for each dog and added to the infusion rate to estimate total excretion. Statistical analysis of results revealed very good correlation with "true" excretion and only small differences in the usefulness of each factor to enable prediction of total excretion. Area and volume factors are slightly better than length factors. Since the area factor is more simply derived, it is the method of choice for the small boluses occurring in the dog's ureter. The accuracy of the method is such that it would appear best suited to serve as a screening method, recognizing as different those determinations with observed differences in excretion above 0.2 cc. per minute. The associated rate of false positives and the rate of false negatives is presented.

The ureter adapts to increasing volume by elongation of the contrast bolus formed and no detectable widening. There is no consistent change in the frequency of peristaltic contractions with changing rates of urinary flow in the physiologic range.

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