An experimental approach to explain some misinterpretations of diuresis renography.

Since its introduction in 1978, gamma camera diuresis renography has proved a useful technique in the differential diagnosis of the dilated renal pelvis. Comparative analyses with perfusion pressure flow studies have revealed discrepancies in a number of cases. These may have been caused in part by incorrect interpretation of the renograms. A renal pelvis model has been developed that permits renograms to be obtained for different renal pelvis volumes, different flow rates and different degrees of obstruction. The results show that a curve approaching an exponential function after increased flow rules out an obstruction. A slight flattening of the curve, however, is indicative of obstruction. Failure to take note of these finer distinctions can lead to misinterpretations.