Deconvolution analysis of renograms obtained with simultaneously administered 99mTc-DTPA and 131I-Hippuran

Seventy patients were studied with a dual radionuclide technique. The conventional renograms and the blood curve were subjected to deconvolution analysis using the matrix algorithm method, and the following curve data calculated from the retention functions: absolute and relative amplitudes, minimum time of the retention function, maximum time of the retention function and mean transit time. The findings with the two radiopharmaceuticals 99mTc-DTPA and 131I-Hippurin were compared under normal and pathological conditions. The correlations between the data with 99mTc-DTPA and those with 131I-Hippuran were highly significant (p<0.01). So was the correlation between the absolute amplitude of the retention curve and the rate of uptake based on the corresponding renogram (p<0.01). Due to the difference in the renal handling of the two tracers, longer maximum times were obtained with 99mTc-DTPA. The mean transit times were also longer with 99mTc-DTPA, except in kidneys with parenchymal insufficiency. The highest amplitudes were found in normal kidneys, while the lowest values were observed in parenchymal insufficiency. In the group with acute ureteral obstruction, the mean transit times tended to be increased. The maximum times were even more increased. With both tracers it is possible to distinguish between the three groups of renal conditions studied here: Normal, parenchymal insufficiency, and acute ureteral obstruction. (orig.)