Diuresis renography and parenchymal transit times in the assessment of renal pelvic dilatation.

A comparison has been made between the results of diuresis renography and deconvolution analysis of the renogram in 36 patients (46 kidneys) with urographically demonstrated renal pelvic dilatation. The mean transit times obtained by deconvolution analysis of the parenchymal renograms of eight normal volunteers had a mean value of 2.8 + 0.6 (S.D.) min, and the upper limit of normal was thus established as 4 min. Twenty-two of 29 kidneys (76%) with nonobstructive diuresis renograms had parenchymal mean transit times of 4 min or below. Fourteen out of 17 kidneys (82%) with obstructive diuresis renograms had parenchymal mean transit times above 4 min. Both investigations may contribute to the noninvasive assessment of dilated renal pelves; the parenchymal retention function (quantified by mean transit time) assesses the effects of dilatation on tubular transit and renal function, whereas the diuresis renogram is a more specific test for evaluating impedance to flow.